EL+servlet+jsp實現簡單的投票程序版本一

時間 2019-11-12

標籤 el+servlet+jsp servlet jsp 實現簡單投票程序版本欄目 Tomcat 简体版

原文原文鏈接

若是你尚未EL基礎的話請看個人前面幾篇博客： html

EL表達式（一）：http://my.oschina.net/passer007/blog/608675 java

EL表達式（二）：http://my.oschina.net/passer007/blog/610221 編程

EL表達式中的隱含對象：http://my.oschina.net/passer007/blog/610380 app

index.jsp jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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>
	你比較喜歡下列哪一種編程語言？
	<form name = "form1" method = "post" action = "<%=request.getContextPath() %>/PollServlet">
		<input name = "item" type = "radio" class = "noborder" value = "Python" checked>Python
		<input name = "item" type = "radio" class = "noborder" value = "Java">Java
		<input name = "item" type = "radio" class = "noborder" value = "Ruby">Ruby
		<input name = "item" type = "radio" class = "noborder" value = "C#">C#
		<input name = "item" type = "radio" class = "noborder" value = "PHP">PHP
		<input type = "submit" name = "submit" value = "提交">
		<input type = "button" name = "submit2" value = "查看結果" onClick = "window.location.href='showResult.jsp'">
	</form>
</body>
</html>

showResult.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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>
	你比較喜歡下列哪一種編程語言？
	<ul>
		<li>Python  :${applicationScope.pollResult["Python"]}</li>
		<li>Java    :${applicationScope.pollResult["Java"]}</li>
		<li>Ruby    :${applicationScope.pollResult["Ruby"]}</li>
		<li>C#      :${applicationScope.pollResult["C#"]}</li>
		<li>PHP     :${applicationScope.pollResult["PHP"] }</li>
	</ul>
</body>
</html>

PollServlet.java

package com.zhong.el;

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());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	@SuppressWarnings("unchecked")
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		request.setCharacterEncoding("GBK");
		String item = request.getParameter("item");
		System.out.println(item);
		ServletContext context = request.getSession().getServletContext();
		@SuppressWarnings("rawtypes")
		Map map = null;
		if(context.getAttribute("pollResult")!=null){
			map = (Map) context.getAttribute("pollResult");
			map.put(item,Integer.parseInt(map.get(item).toString())+1);
		}else{
			String[] arr = {"Python","Java","Ruby","C#","PHP"};
			map = new HashMap();
			for(int i = 0 ; i < arr.length ; i++){
				if(item.equals(arr[i])){
					map.put(arr[i], "1");
				}else{
					map.put(arr[i], "0");
				}
			}
		}
		context.setAttribute("pollResult", map);
		response.setCharacterEncoding("GBK");
		PrintWriter pw = response.getWriter();
		pw.println("<script>alert('投票成功！');window.location.href = 'showResult.jsp';</script>");
	}

}

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