2019-12-13

會話(session)

會話他是一個作用域锰什，可以存值，可以取值玉工，session的id一樣羽资，就是同一個會話，不一樣遵班，就不是同一個會話

實現(xiàn)session有兩種形式

cookies(默認)

cookie被禁用屠升，url重寫

當cookie被禁用，session不好使了,在提交的后面加一個狭郑；jsessionid=session.getid

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n128" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//獲取session</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">HttpSession session = request.getSession();</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n129" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">session.isNew()</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">返回值true,false,判斷這個session是不是新的會話</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n130" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//session設置會話有效時間</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">session.setMaxInactiveInterval(60*60);</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n131" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//會話最后訪問時間</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">session.getLastAccessedTime()</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n132" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//會話創(chuàng)建時間</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">session.getCreationTime()</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n133" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//獲取會話有效時間</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">session.getMaxInactiveInterval()</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n134" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//獲取Id</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">session.getId()</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n135" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//添加腹暖，第二個值是object類型</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">session.setAttribute("count",count);</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n136" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//獲取返回值object</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">session.getAttribute("count")</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">?</pre>

</pre>

servlet2.5,3.0區(qū)別

2.5要在web.xml中配置，3.0不用翰萨，但得寫注解脏答，2.5配置文件會越來越多

jsp

servlet缺點：寫html代碼費勁，寫java代碼方便(java代碼里嵌入html)

jsp:就是一個servlet，是servlet升級版殖告，寫html方便(html里嵌入java代碼)

嵌入java代碼用<% %>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n151" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><%</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"> Date time=new Date();</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">out.print("<h3>time:"+time+"<h3>");</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">%></pre>

</pre>

當你第一次使用jsp時糙麦，速度略微慢點

jsp編譯過程:先編譯成servlet，在編譯成.class文件丛肮，在運行在虛擬機上.

jsp注釋:

使用“//”對單行代碼進行注釋

使用“/* */”方式對多行代碼進行注釋

使用“/** */”方式對多行代碼進行注釋

使用“<%-- --%>”對多行代碼進行注釋(客戶端不能查看到 )

使用“”對多行HTML代碼進行注釋這(客戶端可以查看到)

指令

page指令:

include指令

include 指令用于在運行時將 HTML文件或 JSP頁面嵌入到另一個 JSP頁面 "

<%@ include file = "/foot.jsp" %>

聲明的概念

JSP聲明就是在JSP頁面中聲明Java方法

1：<%!public int x=10;%>(聲明標記:聲明一個屬性,方法赡磅，以后不用，用了就錯了)

2：標記：書寫java代碼的地方

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n185" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><% </pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">String name="哈哈";</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">int count=100;</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">%></pre>

</pre>

3:輸出標記

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n188" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h1>輸出標記:</h1></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h3>name:<%=name %></h3></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h3>count:<%=count+10 %></h3></pre>

</pre>

jsp隱式對象

request

也是一個域宝与，可以傳值到jsp

request.setAttribute()

第一個參數(shù)字符串焚廊，第二個object類型

request.getAttribute()

參數(shù)是字符串，返回值是object類型

request.getContextPath()工程目錄

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n205" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><%=request.getContextPath() %>/index.jsp</pre>

</pre>

2種跳轉(zhuǎn)頁面方法习劫，第二種request值可以傳過去this.findAll(request, response);

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n209" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//跳轉(zhuǎn)url地址欄不是最終地址咆瘟，是servlet地址，可以把request作用域里面的值傳過去</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">?</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">request.getRequestDispatcher("MessageServlet?method=findAll").forward(request, response);</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">?</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//地址欄是最終地址欄诽里，request作用域里的值傳不過去袒餐，還可以跳站外資源（例如百度）</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">?</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">response.sendRedirect("MessageServlet?method=findAll");</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">?</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//第二種跳轉(zhuǎn)鏈接可以傳值，第二個頁面可以拿到谤狡。</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">?</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//跳servlet時灸眼，不一定調(diào)用dopost，還是doget,看根源處走的是什么</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">?</pre>

</pre>

隱式對象

輸入輸出：request 墓懂，response,out

作用域通信:session,application,PageContext

Servlet對象：page（Object類型對象）config（配置文件信息）

錯誤對象：exception

application:作用于整個應用服務器的全局作用域

request：出了這個請求響應就不能用

session：不是一個ID就不能用

pageContext:當前頁面作用域

錯誤

04(路徑錯誤)

500（代碼錯誤）

401（驗證錯誤）

405（doPost/doGet方法不全）

編寫顯示錯誤的頁面

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n241" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//在web.xml文件中配置焰宣，寫jsp錯誤頁面，location里面是jsp文件路徑</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><error-page></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"> <error-code>404</error-code></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"> <location>/error404.jsp</location></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"> </error-page></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"> <error-page></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"> <error-code>500</error-code></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"> <location>/error500.jsp</location></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"> </error-page></pre>

</pre>

Jsp El

1.減少JSP頁面中Java代碼

2.方便JSP中代碼的修改捕仔，也方便美工修改頁面外觀

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n250" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h3>10+10=<%=10+10 %></h3></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h3>10+10=${10+10 }</h3></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">效果差不多</pre>

</pre>

<pre class="md-fences md-end-block" lang="" contenteditable="false" cid="n251" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">

<textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="box-sizing: border-box; overflow: auto; color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; margin: 0px; position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h3>name=<%=x %></h3> //x是get取到的</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h3>name2=${name }</h3>//前面的set方法第一個參數(shù)叫name</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;">//u是set的第一個參數(shù)匕积，第二個參數(shù)是u這個對象，el表達式可以支架用第一個參數(shù)點出對象中的屬性</pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h3>username:${u.username }</h3></pre>

<pre class=" CodeMirror-line " role="presentation" style="box-sizing: border-box; overflow: visible; font-family: inherit; font-size: inherit; white-space: pre-wrap; line-height: 1.71429em; break-inside: avoid; padding: 0px 4px; border-radius: 0px; border-top-width: 0px; border-right: none; border-bottom-width: 0px; border-left-width: 0px; background: 0px 0px; margin: 0px; word-wrap: break-word; color: inherit; z-index: 2; position: relative; word-break: normal; width: inherit;"><h3>pwd:${u.pwd }</h3></pre>

</pre>

[圖片上傳失敗...(image-a1653d-1576216451512)]

JSP EL的內(nèi)置對象

requestScope

sessionScope

applicationScope

param

paramValues

el表達式讀取順序

page-request-session-application

當四個域的set方法存的第一個參數(shù)一樣時榜跌，有固定的讀取順序

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n271" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">//內(nèi)置對象的用法闪唆，固定讀取
<h3>name: ${requestScope.name};</h3> <h3>name:$ {sessionScope.name};</h3>
<h3>name:${applicationScope.name};</h3>
</pre>

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n272" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 0px; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">//同request.getParmeter("name")
<h3>name4:${param.name};</h3>
</pre>

MVC

是一種編程的思想，包括M V C ,m:數(shù)據(jù)模型钓葫。V：顯示層 C：控制層悄蕾，能使各層都分開，便于我們?nèi)粘５姆止ず献魅勘疲茉黾右稽c代碼的復雜度

定制標記庫

增加表現(xiàn)層的處理能力

減少JSP文件中的Java代碼

定制標記的作用類似

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n285" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">//導入標記庫
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
</pre>

1.set標簽笼吟，可以向不同的作用域里傳值

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n290" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"><c:set var="name2" scope="session" value="session里面的值"></c:set>
</pre>

2.放在catch標簽里，即使錯誤霸旗，程序也能繼續(xù)運行

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n293" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"><c:catch var="e">
<%
int p=Integer.parseInt(request.getParameter("page")) ;

%>
<h3>page=<%=p %></h3>

</c:catch>
//錯誤信息
<h3>e=${e}</h3>
</pre>

3.if標簽贷帮，跟if語句一樣,沒有else

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n296" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"><c:if test=" ${empty name3 }"> <h3>name3里面為空</h3> </c:if> <c:if test="$ { not empty name3 }">
<h3>name3里面不為空name3=${name3}</h3>

</c:if>
</pre>

4.choose標簽，和when標簽一起使用诱告，相當于else if,otherwide標簽相當于else

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n299" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"><c:choose>
<c:when test=" ${param.p<10 }"> <h3>p小于10</h3> </c:when> <c:when test="$ {param.p<50 }">
<h3>p小于50</h3>
</c:when>
<c:otherwise>

<h3>p不小于50</h3>
</c:otherwise>
</c:choose>
</pre>

5循環(huán).標簽撵枢，從1開始，沒回走2，走到10

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n302" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"><c:forEach begin="1" end="10" var="i" step="2" varStatus="s">
i= ${i }==>$ {s.count }

</c:forEach>
</pre>

6.forTokens標簽,以逗號分割

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n305" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 0px; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"><%
request.setAttribute("aihao", "吃,喝,玩,樂");
%>
<c:forTokens items=" ${aihao }" delims="," var="a" varStatus="s">$ {s.index}==>${a }

</c:forTokens>
</pre>

Servlet監(jiān)聽器

在Web應用中響應特定對象的特定事件

1.更加方便的控制application锄禽、session 和request 對象的發(fā)生的特定事件潜必。

2.可以集中處理特定的事件。

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n314" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"> session.invalidate();
//關閉session
</pre>

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n315" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">//當前頁面有session沃但，就用當前session磁滚，沒有也不創(chuàng)建session
<%@page session="false" %>
</pre>

servlet監(jiān)聽器創(chuàng)建過程

需要配置web.xml文件

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n320" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"><listener>
<listener-class>com.neusoft.listener.CountListener</listener-class>
</listener>
</pre>

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n321" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">package com.neusoft.listener;

import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class CountListener implements HttpSessionListener {
public static int count=0;

@Override
public void sessionCreated(HttpSessionEvent arg0) {
// TODO Auto-generated method stub
  count++;
  System.out.println("創(chuàng)建 count="+count);
}

@Override
public void sessionDestroyed(HttpSessionEvent arg0) {
// TODO Auto-generated method stu
count--;
System.out.println("銷毀 count="+count);

}

}

</pre>

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n322" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">package com.neusoft.listener;

import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;

public class MyListener implements HttpSessionAttributeListener {

@Override
public void attributeAdded(HttpSessionBindingEvent arg0) {
System.out.println("添加");

}

@Override
public void attributeRemoved(HttpSessionBindingEvent arg0) {
System.out.println("移除");

}

@Override
public void attributeReplaced(HttpSessionBindingEvent arg0) {
System.out.println("替換");

}

}

</pre>

Servlet過濾器

Filter接口，需要實現(xiàn)這個接口宵晚，有初始化垂攘，執(zhí)行，銷毀3個方法

初始化：在啟動服務時調(diào)用

執(zhí)行：在進入另一個窗口時調(diào)用

銷毀：在關閉服務式調(diào)用

需要配置web.xml文件

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n337" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;"><filter>
<filter-name>正常寫文件名</filter-name>
<filter-class>cm.neusoft.filter.MyFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>正常寫文件名</filter-name>
<url-pattern>/</url-pattern>
// /代表所有都過濾,即使地址寫錯了淤刃，或者沒有這個地址晒他，也都會過濾
</filter-mapping>
</pre>

<pre class="md-fences mock-cm md-end-block" lang="" contenteditable="false" cid="n338" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9rem; white-space: pre-wrap; line-height: 1.71429em; text-align: left; break-inside: avoid; display: block; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(218, 218, 218); position: relative !important; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; margin-left: 2em; width: inherit;">package cm.neusoft.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class MyFilter implements Filter{

@Override
public void destroy() {
System.out.println("銷毀");

}

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
System.out.println("執(zhí)行");
/*

如果有下一個filter,執(zhí)行下一個filter

如果沒有下一個filter,執(zhí)行原請求
*/
chain.doFilter(request, response);
}

@Override
public void init(FilterConfig arg0) throws ServletException {
System.out.println("初始化");

}

}

</pre>

由一個jsp跳到一個servlet，然后這個servlet以.forward跳到另一個jsp或者servlet里面逸贾，下一個jsp或者servlet不會被攔截(不會被過濾)陨仅。

當跳轉(zhuǎn)的時候，以sendRedirect進行跳轉(zhuǎn)的時候铝侵，無腦被過濾灼伤，以.forward跳轉(zhuǎn)的時候，跳轉(zhuǎn)的界面不會被過濾

?著作權歸作者所有,轉(zhuǎn)載或內(nèi)容合作請聯(lián)系作者

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2019-12-13

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