web服務(wù)器收到客戶端的http請(qǐng)求,會(huì)針對(duì)每一次請(qǐng)求荐操,分別創(chuàng)建一個(gè)用于代表請(qǐng)求的request對(duì)象和代表響應(yīng)的response對(duì)象
HttpServletResponse對(duì)象
該對(duì)象封裝了向客戶端發(fā)送數(shù)據(jù)托启、發(fā)送響應(yīng)頭屯耸、發(fā)送響應(yīng)狀態(tài)碼的方法
響應(yīng)
部分常用方法
繼承關(guān)系
代碼案例
- 重定向
- 頁(yè)面定時(shí)刷新
- 禁用瀏覽器緩存
- 向頁(yè)面輸出中文
- 實(shí)現(xiàn)文件下載
- 實(shí)現(xiàn)驗(yàn)證碼
重定向
login.html文件
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/day10/login" method="post"> <!-- action 提交到該servlet-->
<table border="1" width="50%">
<tr>
<td>輸入姓名</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>輸入密碼</td>
<td><input type="password" name="password"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="提交"></td>
</tr>
</table>
</form>
</body>
</html>
界面
/**
* 重定向
* @author limaoquan
*
*/
public class login extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
/**
* 先獲取表單的內(nèi)容(request)
* 判斷姓名和密碼是否都是admin
* 如果有一個(gè)不是链方,就重定向到登陸頁(yè)面灶搜,否則就登陸成功
*/
String username = request.getParameter("username");//程序入口
String password = request.getParameter("password");
if("admin".equals(username) && "admin".equals(password)){
//登陸成功
response.setContentType("text/html;charset=UTF-8");//否則會(huì)亂碼
response.getWriter().write("登陸成功...");
}else{
//重定向登陸頁(yè)面
//設(shè)置302的狀態(tài)碼
response.setStatus(302);
response.setHeader("location", "/day10/response/login.html");
//第二種方法重定向割卖,把上面兩步合起來(lái)
response.sendRedirect("/day10/response/login.html");
}
}
頁(yè)面定時(shí)刷新
/**
* 頁(yè)面的定時(shí)跳轉(zhuǎn)
* @author limaoquan
*
*/
public class RefreshServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
//response.setHeader("ContentType","text/html;charset=UTF-8");
response.getWriter().write("<h1>頁(yè)面將在5秒后跳轉(zhuǎn)</h1>");
response.setHeader("refresh", "5, url=/day10/response/login.html");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
html與response
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta http-equiv="refresh" content="5;url=/day10/response/login.html">
<title>Insert title here</title>
</head>
<body onload="run()">
<h2>頁(yè)面將在<span id="spanId">5</span>秒后跳轉(zhuǎn)</h2>
</body>
<script type="text/javascript">
/*
讀秒的操作
加載事件 onload
*/
var x = 5;
function run(){
var span = document.getElementById("spanId");
span.innerHTML = x;
x--;
window.setTimeout("run()", 1000);
}
</script>
</html>
禁用瀏覽器緩存
public class cep extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//設(shè)置三個(gè)頭信息禁用緩存
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");
response.setDateHeader("Expires", -1);
//向頁(yè)面輸出當(dāng)前的時(shí)間
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
response.getWriter().write(sdf.format(date));
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
向頁(yè)面輸出中文(亂碼問(wèn)題)
ServletOutputStream getOutputStream() 字節(jié)輸出流
* 解決辦法:
* * 設(shè)置瀏覽器打開(kāi)文件時(shí)采用的編碼
* * 獲取字符串byte數(shù)組時(shí)編碼和打開(kāi)文件時(shí)編碼一致1
//設(shè)置瀏覽器打開(kāi)文件的編碼
response.setHeader("Content-Type", "text/html; charset= UTF-8");
//獲取字節(jié)輸出流
OutputStream os = response.getOutputStream();
//輸出中文
os.write("哈嘍我的".getBytes("UTF-8"));
PrintWriter getWriter() 字符輸出流
//設(shè)置緩沖區(qū)的編碼
response.setCharacterEncoding("UTF-8");
//設(shè)置瀏覽器打開(kāi)文件時(shí)的編碼
response.setHeader("Content-Type", "text/html; charset= UTF-8");
response.getWriter().write("花生及多個(gè)");
//簡(jiǎn)寫(xiě)的形式
response.setContentType("text/html; charset= UTF-8");
response.getWriter().write("花生及多個(gè)");
文件下載初級(jí)
- 超鏈接下載
- 如果瀏覽器不能識(shí)別的格式,會(huì)彈出下載窗口
- 如果識(shí)別的話肺孵,會(huì)默認(rèn)打開(kāi)文件
- 后臺(tái)程序下載
- response.setHeader(Content-Disposition”,” attachment;filename=”文件名稱(chēng))
- 通過(guò)response.getOutputStream()向?yàn)g覽器端輸出
//第一個(gè)版本
public class DownloadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path = getServletContext().getRealPath("/img/Koala.jpg");//服務(wù)器端不帶項(xiàng)目名
//設(shè)置頭信息
response.setHeader("Content-Disposition", "attachment;filename = Koala.jpg");
System.out.println(request.getRemoteAddr());//打印請(qǐng)求端ip
//先獲取文件平窘,讀入輸入流中
InputStream in = new FileInputStream(path);
//通過(guò)response讀出到客戶端
OutputStream os = response.getOutputStream();
//io的拷貝
byte[] b = new byte[1024];
int len = 0;
while((len = in.read(b))!= -1){
os.write(b,0,len);
}
in.close();
//os.close(); 服務(wù)器會(huì)管理
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
//第二個(gè)版本
public class DownloadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path = getServletContext().getRealPath("/img/Koala.jpg");//服務(wù)器端不帶項(xiàng)目名
//包含文件名稱(chēng) C:\tomcat\webapps\day10\img\Koala.jpg
//截取文件的名稱(chēng) Koala.jpg
String filename = null;
int index = path.lastIndexOf("\\");
if(index != -1){
filename = path.substring(index+1);
}
//設(shè)置頭信息
response.setHeader("Content-Disposition", "attachment;filename = "+ filename);
System.out.println(request.getRemoteAddr());//打印請(qǐng)求端ip
//先獲取文件是鬼,讀入輸入流中
InputStream in = new FileInputStream(path);
//通過(guò)response讀出到客戶端
OutputStream os = response.getOutputStream();
//io的拷貝
byte[] b = new byte[1024];
int len = 0;
while((len = in.read(b))!= -1){
os.write(b,0,len);
}
in.close();
//os.close(); 服務(wù)器會(huì)管理
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
//中文亂碼問(wèn)題
public class DownloadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path = getServletContext().getRealPath("/img/考拉.jpg");//服務(wù)器端不帶項(xiàng)目名
//包含文件名稱(chēng) C:\tomcat\webapps\day10\img\Koala.jpg
//截取文件的名稱(chēng) Koala.jpg
String filename = null;
int index = path.lastIndexOf("\\");
if(index != -1){
filename = path.substring(index+1);
}
//如果文件名為中文會(huì)出現(xiàn)亂碼均蜜,需要判斷什么瀏覽器
String agent = request.getHeader("User-agent");
if(agent.contains("MSIE")){//IE瀏覽器,只適用IE
filename = URLEncoder.encode(filename,"UTF-8");
}
//設(shè)置頭信息
response.setHeader("Content-Disposition", "attachment;filename = "+ filename);
System.out.println(request.getRemoteAddr());//打印請(qǐng)求端ip
//先獲取文件囤耳,讀入輸入流中
InputStream in = new FileInputStream(path);
//通過(guò)response讀出到客戶端
OutputStream os = response.getOutputStream();
//io的拷貝
byte[] b = new byte[1024];
int len = 0;
while((len = in.read(b))!= -1){
os.write(b,0,len);
}
in.close();
//os.close(); 服務(wù)器會(huì)管理
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
驗(yàn)證碼
大體步驟:
- 在內(nèi)存中生成圖片
- 可以使用BufferedImage對(duì)象
- getGraphics() 獲取畫(huà)筆對(duì)象
- 隨機(jī)生成字母或數(shù)字
- Random對(duì)象
- 把生成的數(shù)字或字母寫(xiě)在圖片上
- 通過(guò)畫(huà)筆中的方法
- 把圖片生成到頁(yè)面上
- 可以使用ImageIO對(duì)象
驗(yàn)證碼的分析
/**
* 驗(yàn)證碼
* @author limaoquan
*
*/
public class yanzhengma extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//在內(nèi)存中生成圖片
int width = 120;
int height = 30;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 獲取畫(huà)筆對(duì)象
Graphics g = image.getGraphics();
g.setColor(Color.yellow);
//畫(huà)一個(gè)矩形
g.fillRect(0, 0, width, height);
g.setColor(Color.black);
g.drawRect(1, 0, width-1, height-1);
//準(zhǔn)備數(shù)據(jù),隨機(jī)獲取4個(gè)字符
String words = "ASDFWEIDDFJKFKSHDKFHSJSKD1234858976";
Random random = new Random();
g.setColor(Color.red);
g.setFont(new Font("隸書(shū)",Font.BOLD,20));
Graphics2D g2 = (Graphics2D)g;
int x = 20;
int y = 20;
for(int i = 0;i<4;i++){
int degree = random.nextInt(60)-30;
double hudu = degree * Math.PI / 180;
g2.rotate(hudu,x,y);
int index = random.nextInt(words.length());
char ch = words.charAt(index);
g2.drawString(""+ch, x, y);
g2.rotate(-hudu,x,y);
x= x + 30;
}
//把內(nèi)存中的圖片寫(xiě)到瀏覽器端
ImageIO.write(image, "jpg", response.getOutputStream());
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
//常用漢字聪铺,只需要把以上String words替換掉就可以
String base = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";
登錄界面與驗(yàn)證碼結(jié)合
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/day10/login" method="post">
<table border="1" width="50%">
<tr>
<td>輸入姓名</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>輸入密碼</td>
<td><input type="password" name="password"></td>
</tr>
<tr>
<td>輸入驗(yàn)證碼</td>
<td>
<input type="text" name="code">
![](/day10/yanzheng)
<a href="#" onclick="run()">看不清查刻,換一張</a>
</td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="提交"></td>
</tr>
</table>
</form>
</body>
<script type="text/javascript">
//看不清穗泵,換一張,時(shí)間戳
function run(){
var image = document.getElementById("imgId");
image.src = "/day10/yanzheng?"+ new Date().getTime();//加時(shí)間戳
}
</script>
</html>
界面