通过 EL + servlet显示投票结果

Myth丶恋晨 2024-02-17 21:44 19阅读 0赞

1、投票界面 （index.jsp）

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <!DOCTYPE HTML>
    <html>
    <head>
    <meta charset="utf-8">
    <title>应用EL表达式显示投票结果</title>
    <style>
    ul{
    	list-style: none;
    }
    li{
    	padding:5px;
    }
    
    </style>
    </head>
    <body>
    <h3>您最需要哪方面的编程类图书？</h3>
    <form name="form1" method="post" action="PollServlet">
    <ul>
    	<li><input name="item" type="radio" class="noborder" value="基础教程类" checked>基础教程类</li>
    	<li><input name="item" type="radio" class="noborder" value="实例集锦类">实例集锦类 </li>
        <li><input name="item" type="radio" class="noborder" value="经验技巧类">经验技巧类</li>
        <li> <input name="item" type="radio" class="noborder" value="速查手册类">速查手册类</li>
        <li><input name="item" type="radio" class="noborder" value="案例剖析类">案例剖析类</li>
        <li> <input name="Submit" type="submit" class="btn_grey" value="投票"> 
    <input name="Submit2" type="button" class="btn_grey" value="查看投票结果" onClick="window.location.href='showResult.jsp'"></li>
    </ul>
    </form>
    </body>
    </html>

2、servlet 处理代码： （PollServlet.java）

package com;
    
    import java.awt.Window;
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.HashMap;
    import java.util.Map;
    
    import javax.servlet.ServletContext;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    /**
     * Servlet implementation class PollServlet
     */
    @WebServlet("/PollServlet")
    public class PollServlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
           
        /**
         * @see HttpServlet#HttpServlet()
         */
        public PollServlet() {
            super();
            // TODO Auto-generated constructor stub
        }
    
    	/**
    	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		//response.getWriter().append("Served at: ").append(request.getContextPath());
    	  
    		request.setCharacterEncoding("UTF-8");
    		Map mp = null;	    
    		String typ= request.getParameter("item");
    		
    		ServletContext sContext=request.getSession().getServletContext();
    		int tl=0;
    	    
    		if(sContext.getAttribute("result")!=null){
              mp=(Map) sContext.getAttribute("result");
               mp.put(typ, Integer.parseInt(mp.get(typ).toString())+1);
          
               tl=(int)sContext.getAttribute("tol");
               tl++;
    		}
    		else {
    			String []str={"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"};
    			mp=new HashMap();
    			
    			for(int i=0;i<str.length;i++){	
    		    	if(str[i].equals(typ)){
    		    		mp.put(str[i], 1);
    		    		tl=1;
    		    	}
    		    	else {
    		    		mp.put(str[i], 0);
    		    	}
    		    }
    		}
    		
    		sContext.setAttribute("tol", tl);
    		sContext.setAttribute("result", mp);
    		//设置响应的类型和编码方式，如果不设置，弹出对话框中的文字将显示乱码
    		response.setContentType("text/html;charset=UTF-8");
    		PrintWriter out=response.getWriter();
    		out.println("<script>alert('投票成功!');window.location.href='showResult.jsp';</Script> ");
    	}
    
    	/**
    	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    	 */
    	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		doGet(request, response);
    	}
    
    }

3、EL 结果显示（showResult.jsp）

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <!DOCTYPE HTML>
    <html>
    <head>
    <meta charset="utf-8">
    <title>显示投票结果页面</title>
    <style>
    ul{
    	list-style: none;
    }
    li{
    	padding:5px;
    }
    </style>
    </head>
    <body>
    <h3>您最需要哪方面的编程类图书？</h3>
    <form name="form1" method="post" action="PollServlet">
    <ul>
    	<li>基础教程类： <img src="bar.gif" width='${220*(applicationScope.result["基础教程类"]/applicationScope.tol)}' height="13">
    	  （${empty applicationScope.result["基础教程类"]? 0 :applicationScope.result["基础教程类"]}）</li>
    	<li>实例集锦类： <img src="bar.gif" width='${220*(applicationScope.result["实例集锦类"]/applicationScope.tol)}' height="13">
    	  （${empty applicationScope.result["实例集锦类"] ? 0 :applicationScope.result["实例集锦类"]}）</li>
          <li>经验技巧类： <img src="bar.gif" width='${220*(applicationScope.result["经验技巧类"]/applicationScope.tol)}' height="13">
    	  （${empty applicationScope.result["经验技巧类"] ? 0 :applicationScope.result["经验技巧类"]}）</li>
          <li>速查手册类： <img src="bar.gif" width='${220*(applicationScope.result["速查手册类"]/applicationScope.tol)}' height="13">
    	  （${empty applicationScope.result["速查手册类"] ? 0 : applicationScope.result["速查手册类"]}）</li>
          <li>案例剖析类： <img src="bar.gif" width='${220*(applicationScope.result["案例剖析类"]/applicationScope.tol)}' height="13">
    	  （${empty applicationScope.result["案例剖析类"] ? 0 :applicationScope.result["案例剖析类"]}）</li>
          <li> 合计：${applicationScope.tol}人投票！
            <input name="Button" type="button" class="btn_grey" value="返回" onClick="window.location.href='index.jsp'"></li>
    </ul>
    </form>
    </body>
    </html>

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[Center 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/f4c061367672495dba792c9f49a25120.png