• 歷史記錄可以session陆爽，可以cookie也可以redis，扳缕，在cookies時(shí)候是拼一個(gè)字符串記錄所在商品id用符號(hào)隔開(kāi)慌闭，然后在返回原來(lái)頁(yè)面取出來(lái)，需要的參數(shù)沒(méi)有在上級(jí)找躯舔，再?zèng)]有繼續(xù)向上

----取出cookie---
protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 獲得cid
        String cid = request.getParameter("cid");
        String currentPageStr = request.getParameter("currentPage");
        if (currentPageStr == null)
            currentPageStr = "1";
        int currentPage = Integer.parseInt(currentPageStr);
        int currentCount = 12;
        ProductService service = new ProductService();
        PageBean pageBean = service.findProductListByCid(cid, currentPage, currentCount);
        request.setAttribute("pageBean", pageBean);
        request.setAttribute("cid", cid);
        // 定義一個(gè)記錄歷史商品信息的集合
        List<Product> historyProductList = new ArrayList<Product>();
        // 獲得客戶端攜帶名字叫pids的cookie
        Cookie[] cookies = request.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                if ("pids".equals(cookie.getName())) {
                    String pids = cookie.getValue();// 3-2-1
                    String[] split = pids.split("-");
                    for (String pid : split) {
                        Product pro = service.findProductByPid(pid);
                        historyProductList.add(pro);
                    }
                }
            }
        }

        // 將歷史記錄的集合放到域中
        request.setAttribute("historyProductList", historyProductList);
        request.getRequestDispatcher("/product_list.jsp").forward(request, response);
}
-------------在詳情頁(yè)放入cookie---------------
// 獲得客戶端攜帶cookie---獲得名字是pids的cookie
        String pids = pid;
        Cookie[] cookies = request.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                if ("pids".equals(cookie.getName())) {
                    pids = cookie.getValue();
                    // 1-3-2 本次訪問(wèn)商品pid是8----->8-1-3-2
                    // 1-3-2 本次訪問(wèn)商品pid是3----->3-1-2
                    // 1-3-2 本次訪問(wèn)商品pid是2----->2-1-3
                    // 將pids拆成一個(gè)數(shù)組
                    String[] split = pids.split("-");// {3,1,2}
                    List<String> asList = Arrays.asList(split);// [3,1,2]
                    LinkedList<String> list = new LinkedList<String>(asList);// [3,1,2]
                    // 判斷集合中是否存在當(dāng)前pid
                    if (list.contains(pid)) {
                        // 包含當(dāng)前查看商品的pid
                        list.remove(pid);
                        list.addFirst(pid);
                    } else {
                        // 不包含當(dāng)前查看商品的pid 直接將該pid放到頭上
                        list.addFirst(pid);
                    }
                    // 將[3,1,2]轉(zhuǎn)成3-1-2字符串
                    StringBuffer sb = new StringBuffer();
                    for (int i = 0; i < list.size() && i < 7; i++) {
                        sb.append(list.get(i));
                        sb.append("-");// 3-1-2-
                    }
                    // 去掉3-1-2-后的-
                    pids = sb.substring(0, sb.length() - 1);
                }   }   }
        Cookie cookie_pids = new Cookie("pids", pids);
        response.addCookie(cookie_pids);
        request.getRequestDispatcher("/product_info.jsp").forward(request, response);
    }

• 腳本：在jsp中寫<%java代碼%>驴剔？；ajax粥庄，在script中異步加載數(shù)據(jù)$.post
• 動(dòng)態(tài)引入時(shí)候在加載時(shí)候就將數(shù)據(jù)返回給頁(yè)面其余加載時(shí)候便會(huì)統(tǒng)一加載到數(shù)據(jù)（使用ajax加載header中的目錄條）
• 不經(jīng)常改變的可以放在緩存丧失，讀取快比如分類

-----------redis工具包---
-----配置
redis.maxIdle=30
redis.minIdle=10
redis.maxTotal=100
redis.url=localhost
redis.port=6379
------
public class JedisPoolUtils {
    private static JedisPool pool = null;
    static {
        // 加載配置文件
        InputStream in = JedisPoolUtils.class.getClassLoader().getResourceAsStream("redis.properties");
        Properties pro = new Properties();
        try {
            pro.load(in);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 獲得池子對(duì)象
        JedisPoolConfig poolConfig = new JedisPoolConfig();
        poolConfig.setMaxIdle(Integer.parseInt(pro.get("redis.maxIdle").toString()));// 最大閑置個(gè)數(shù)
        poolConfig.setMinIdle(Integer.parseInt(pro.get("redis.minIdle").toString()));// 最小閑置個(gè)數(shù)
    poolConfig.setMaxTotal(Integer.parseInt(pro.get("redis.maxTotal").toString()));// 最大連接數(shù)
        pool = new JedisPool(poolConfig, pro.getProperty("redis.url"),
                Integer.parseInt(pro.get("redis.port").toString()));
    }
    // 獲得jedis資源的方法
    public static Jedis getJedis() {
        return pool.getResource();  }
    public static void main(String[] args) {
        Jedis jedis = getJedis();
        System.out.println(jedis.get("xxx"));
    }
}
------------------ajax綁定數(shù)據(jù)到j(luò)sp
<script type="text/javascript">
            //header.jsp加載完畢后 去服務(wù)器端獲得所有的category數(shù)據(jù)
            $(function(){
                var content = "";
                $.post(
                    "${pageContext.request.contextPath}/categoryList",
                    function(data){
                        //[{"cid":"xxx","cname":"xxxx"},{},{}]
                        //動(dòng)態(tài)創(chuàng)建<li><a href="#">${category.cname }</a></li>
                        for(var i=0;i<data.length;i++){
                            content+="<li><a href='${pageContext.request.contextPath}/productListByCid?cid="+data[i].cid+"'>"+data[i].cname+"</a></li>";
                        }
                        
                        //將拼接好的li放置到ul中
                        $("#categoryUl").html(content);
                    },
                    "json"
                );
            });
        </script>
--------------------categoryListservlet中的返回?cái)?shù)據(jù)操作---gson轉(zhuǎn)json
protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        ProductService service = new ProductService();
        
        //先從緩存中查詢categoryList 如果有直接使用 沒(méi)有在從數(shù)據(jù)庫(kù)中查詢 存到緩存中
        //1、獲得jedis對(duì)象 連接redis數(shù)據(jù)庫(kù)
        Jedis jedis = JedisPoolUtils.getJedis();
        String categoryListJson = jedis.get("categoryListJson");
        //2惜互、判斷categoryListJson是否為空
        if(categoryListJson==null){
            System.out.println("緩存沒(méi)有數(shù)據(jù) 查詢數(shù)據(jù)庫(kù)");
            //準(zhǔn)備分類數(shù)據(jù)
            List<Category> categoryList = service.findAllCategory();
            Gson gson = new Gson();
            categoryListJson = gson.toJson(categoryList);
            jedis.set("categoryListJson", categoryListJson);
        }
        
        response.setContentType("text/html;charset=UTF-8");
        response.getWriter().write(categoryListJson);
    }

• Long is=0L;
• servlet找錯(cuò)可以先在servlet中查看進(jìn)去沒(méi)有以區(qū)別錯(cuò)誤位置
• select * from product order by pdate desc limit 0,9排序（降）要9條
• 重定向response布讹，轉(zhuǎn)發(fā)requset
• jstl需要導(dǎo)包 prefix：c
• 默認(rèn)歡迎界面在xml中只留一個(gè)，然后單獨(dú)建頁(yè)面使<%使用response跳轉(zhuǎn)%>

Paste_Image.png

Paste_Image.png

• 自定義validate

------只能使用同步训堆，異步會(huì)是返回值flag 無(wú)法賦值
<script src="js/jquery.validate.min.js" type="text/javascript"></script>
//自定義校驗(yàn)規(guī)則
    $.validator.addMethod(
    //規(guī)則的名稱
    "checkUsername",
    //校驗(yàn)的函數(shù)
    function(value, element, params) {

        //定義一個(gè)標(biāo)志
        var flag = false;
        //value:輸入的內(nèi)容
        //element:被校驗(yàn)的元素對(duì)象
        //params：規(guī)則對(duì)應(yīng)的參數(shù)值
        //目的：對(duì)輸入的username進(jìn)行ajax校驗(yàn)
        $.ajax({
            "async" : false,
            "url" : "${pageContext.request.contextPath}/checkUsername",
            "data" : {
                "username" : value
            },
            "type" : "POST",
            "dataType" : "json",
            "success" : function(data) {
                flag = data.isExist;
            }
        });
        //返回false代表該校驗(yàn)器不通過(guò)
        return !flag;
    }
    );

1.解決也面向servlet傳中文-method=post描验，request.setCharacterEncoding("UTF-8");連用
2.validate導(dǎo)包前臺(tái)驗(yàn)證注冊(cè)（看內(nèi)存源碼）錯(cuò)誤信息會(huì)先看原來(lái)代碼中有沒(méi)有（以class=error和for=sex來(lái)確定是為name=sex準(zhǔn)備的）

<label class="error" for="sex" style="display:none ">您沒(méi)有第三種選擇</label>