JSP内置对象综合实例：投票系统

来源：互联网发布：三维设计教学软件编辑：程序博客网时间：2024/05/21 08:08

建立了两个treemap对象，分别建立了选举号与候选人姓名、选举号与所得票数的关系。

<%TreeMap m=new TreeMap();TreeMap m2=new TreeMap();m.put("1001","张1");m2.put("1001", new Integer(0));m.put("1002","张2");m2.put("1002", new Integer(0));m.put("1003","张3");m2.put("1003", new Integer(0));m.put("1004","张4");m2.put("1004", new Integer(0));m.put("1005","张5");m2.put("1005", new Integer(0));application.setAttribute("rollpara", m);application.setAttribute("rollnum", m2);%>

vote2页面主要有开始选举，浏览票数功能。显示候选人名字的form表单为动态生成的，通过application兑现，获得候选人映射的treemap对象的m，进而获得候选人编号及姓名，产生input多选控件。
同时，通过获取key值，产生超链接，点击候选人的名字可以进入个人介绍页面的静态html。

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><%@ page import="java.util.*" %><!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><%TreeMap m=(TreeMap)application.getAttribute("rollpara");Set se=m.keySet();Iterator it=se.iterator();String s="<form action=vote3.jsp>";while(it.hasNext()){    String key=(String)it.next();    String value=(String)m.get(key);    s+="<a href="+key+".html>"+value+"</a>";    s+="&nbsp&nbsp&nbsp&nbsp&nbsp";    s+="<input type=checkbox name='roll' value='"+key+"'/></br>";   }s+="<input type='submit' value='开始选举'>";s+="</form>";%><body><%=s %><form action="vote4.jsp"><input type="submit" value="浏览票数"/></form></body></html>

vote3页为检测投票者是否合法。通过session变量的mark标志判断。若mark为假，则表示合法，设置mark为true，同时通过遍历application候选人共享的变量m2，是相应候选人的票数+1；若mark为true，表明他已经投过票了，提示无效。

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>    <%@ page import="java.util.*" %><!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><%TreeMap m2=(TreeMap)application.getAttribute("rollnum");Boolean mark=(Boolean)session.getAttribute("mark");if(mark==null){    session.setAttribute("mark",new Boolean(true));    String roll[]=request.getParameterValues("roll");    if(roll!=null){        for(int i=0;i<roll.length;i++){            Integer cur=(Integer)m2.get(roll[i]);            cur++;            m2.put(roll[i],cur);        }    }    out.print("选举成功！</br>");}else{    out.print("你已经选举完毕，不能再选<br>");}%><body><a href="vote2.jsp">返回</a></body></html>

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>    <%@ page import="java.util.*" %><!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><%TreeMap m=(TreeMap)application.getAttribute("rollpara");TreeMap m2=(TreeMap)application.getAttribute("rollnum");Set se=m.keySet();Iterator it=se.iterator();String s="<table border=1>";s+="<tr><th>编号</th><th>姓名</th><th>票数</th></tr>";while(it.hasNext()){    String no=(String)it.next();    String name=(String)m.get(no);    Integer num=(Integer)m2.get(no);    s+="<tr>";    s+="<td>"+no+"</td>";    s+="<td>"+name+"</td>";    s+="<td>"+num+"</td>";    s+="</tr>";}%><body><%=s %><a href="vote2.jsp">返回</a></body></html>

这里写图片描述

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