实战2--应用EL表达式显示投票结果

（1）编写index.jsp页面，用于收集投票信息

<%@ page language="java" pageEncoding="GBK"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>应用EL表达式显示投票结果</title>
    <link rel="stylesheet" type="text/css" href="CSS/style.css">

  </head>
  
  <body><form name="form1" method="post" action="PollServlet">
  <table width="403" height="230" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#666666">
    <tr>
      <td height="30" bgcolor="#EFEFEF">·您最需要哪方面的编程类图书？</td>
    </tr>
    <tr>
      <td bgcolor="#FFFFFF"> <input name="item" type="radio" class="noborder" value="基础教程类" checked>
        基础教程类</td>
    </tr>
    <tr>
      <td bgcolor="#FFFFFF"> <input name="item" type="radio" class="noborder" value="实例集锦类">
      实例集锦类 </td>
    </tr>
    <tr>
      <td bgcolor="#FFFFFF"> <input name="item" type="radio" class="noborder" value="经验技巧类">
      经验技巧类</td>
    </tr>
    <tr>
      <td bgcolor="#FFFFFF"> <input name="item" type="radio" class="noborder" value="速查手册类">
        速查手册类</td>
    </tr>
    <tr>
      <td bgcolor="#FFFFFF"> <input name="item" type="radio" class="noborder" value="案例剖析类">
      案例剖析类</td>
    </tr>
    <tr>
      <td align="center" bgcolor="#FFFFFF">
        <input name="Submit" type="submit" class="btn_grey" value="投票">
&nbsp;
<input name="Submit2" type="button" class="btn_grey" value="查看投票结果" onClick="window.location.href='showResult.jsp'"></td>
    </tr>
  </table>
 </form>
  </body>
</html>

界面如下：

（2）编写投票功能的Servlet

package com.wuyudong.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class PollServlet extends HttpServlet {
    private static final long serialVersionUID = -7264414153802032772L;

    /**
     * The doPost method of the servlet. <br>
     * 
     * This method is called when a form has its tag value method equals to
     * post.
     * 
     * @param request
     *            the request send by the client to the server
     * @param response
     *            the response send by the server to the client
     * @throws ServletException
     *             if an error occurred
     * @throws IOException
     *             if an error occurred
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        request.setCharacterEncoding("GBK"); // 设置请求的编码方式
        String item = request.getParameter("item"); // 获取投票项
        ServletContext servletContext = request.getSession()
                .getServletContext(); // 获取ServletContext对象该对象在application范围内有效
        
        Map map = null;
        if (servletContext.getAttribute("pollResult") != null) {
            map = (Map) servletContext.getAttribute("pollResult"); // 获取投票结果
            map.put(item, Integer.parseInt(map.get(item).toString()) + 1); // 将当前的投票项加1
        } else { // 初始化一个保存投票信息的Map集合，并将选定投票项的投票数设置为1，其他为0
            String[] arr = { "基础教程类", "实例集锦类", "经验技巧类", "速查手册类", "案例剖析类" };
            map = new HashMap();
            for (int i = 0; i < arr.length; i++) {
                if (item.equals(arr[i])) { // 判断是否为选定的投票项
                    map.put(arr[i], 1);
                } else {
                    map.put(arr[i], 0);
                }
            }
        }
        servletContext.setAttribute("pollResult", map); // 保存投票结果到ServletContext对象中
        response.setCharacterEncoding("GBK"); // 设置响应的编码方式，如果不设置弹出的对话框中的文字将乱码
        PrintWriter out = response.getWriter();
        out.println("<script>alert('投票成功！');window.location.href='showResult.jsp';</script>");

    }

}

（3）编写showResult.jsp页面

<%@ page language="java" pageEncoding="GBK"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>显示示投票结果页面</title>
    <link rel="stylesheet" type="text/css" href="CSS/style.css">

  </head>
  
  <body>
  <table width="403" height="230" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#666666">
    <tr>
      <td height="30" colspan="2" bgcolor="#EFEFEF">·您最需要哪方面的编程类图书？</td>
    </tr>
    <tr>
      <td width="79" align="center" bgcolor="#FFFFFF">        基础教程类</td>
      <td width="321" bgcolor="#FFFFFF">&nbsp;<img src="bar.gif" width='${220*(applicationScope.pollResult["基础教程类"]/(applicationScope.pollResult["基础教程类"]+applicationScope.pollResult["实例集锦类"]+applicationScope.pollResult["经验技巧类"]+applicationScope.pollResult["速查手册类"]+applicationScope.pollResult["案例剖析类"]))}' height="13">
      （${empty applicationScope.pollResult["基础教程类"]? 0 :applicationScope.pollResult["基础教程类"]}）</td>
    </tr>
    <tr>
      <td align="center" bgcolor="#FFFFFF">      实例集锦类 </td>
      <td bgcolor="#FFFFFF">&nbsp;<img src="bar.gif" width='${220*(applicationScope.pollResult["实例集锦类"]/(applicationScope.pollResult["基础教程类"]+applicationScope.pollResult["实例集锦类"]+applicationScope.pollResult["经验技巧类"]+applicationScope.pollResult["速查手册类"]+applicationScope.pollResult["案例剖析类"]))}' height="13">
      （${empty applicationScope.pollResult["实例集锦类"] ? 0 :applicationScope.pollResult["实例集锦类"]}）</td>
    </tr>
    <tr>
      <td align="center" bgcolor="#FFFFFF">      经验技巧类</td>
      <td bgcolor="#FFFFFF">&nbsp;<img src="bar.gif" width='${220*(applicationScope.pollResult["经验技巧类"]/(applicationScope.pollResult["基础教程类"]+applicationScope.pollResult["实例集锦类"]+applicationScope.pollResult["经验技巧类"]+applicationScope.pollResult["速查手册类"]+applicationScope.pollResult["案例剖析类"]))}' height="13">
      （${empty applicationScope.pollResult["经验技巧类"] ? 0 :applicationScope.pollResult["经验技巧类"]}）</td>
    </tr>
    <tr>
      <td align="center" bgcolor="#FFFFFF">        速查手册类</td>
      <td bgcolor="#FFFFFF">&nbsp;<img src="bar.gif" width='${220*(applicationScope.pollResult["速查手册类"]/(applicationScope.pollResult["基础教程类"]+applicationScope.pollResult["实例集锦类"]+applicationScope.pollResult["经验技巧类"]+applicationScope.pollResult["速查手册类"]+applicationScope.pollResult["案例剖析类"]))}' height="13">
      （${empty applicationScope.pollResult["速查手册类"] ? 0 : applicationScope.pollResult["速查手册类"]}）</td>
    </tr>
    <tr>
      <td align="center" bgcolor="#FFFFFF">      案例剖析类</td>
      <td bgcolor="#FFFFFF">&nbsp;<img src="bar.gif" width='${220*(applicationScope.pollResult["案例剖析类"]/(applicationScope.pollResult["基础教程类"]+applicationScope.pollResult["实例集锦类"]+applicationScope.pollResult["经验技巧类"]+applicationScope.pollResult["速查手册类"]+applicationScope.pollResult["案例剖析类"]))}' height="13">
      （${empty applicationScope.pollResult["案例剖析类"] ? 0 :applicationScope.pollResult["案例剖析类"]}）</td>
    </tr>
    <tr>
      <td colspan="2" align="center" bgcolor="#FFFFFF">
        合计：${applicationScope.pollResult["基础教程类"]+applicationScope.pollResult["实例集锦类"]+applicationScope.pollResult["经验技巧类"]+applicationScope.pollResult["速查手册类"]+applicationScope.pollResult["案例剖析类"]}人投票！
        <input name="Button" type="button" class="btn_grey" value="返回" onClick="window.location.href='index.jsp'"></td>
    </tr>
  </table>
  </body>
</html>
l>

最后运行界面如下：

posted @ 2015-12-30 16:45  wuyudong  阅读(393)  评论(0)  编辑  收藏  举报
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