Java小項目之：投票系統
今天給大家帶來的是java編寫的投票小系統，代碼簡易，適合初學者練手！
代碼展示：
package com.tarena.wgh.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 {
/**
* 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"); //設置請求的編碼方式
String item=request.getParameter("item"); //獲取投票項
ServletContext servletContext=request.getSession().getServletContext(); //獲取ServletContext對象該對象在application范圍內有效
Map map=null;
if(servletContext.getAttribute("pollResult")!=null){
map=(Map)servletContext.getAttribute("pollResult"); //獲取投票結果
map.put(item,Integer.parseInt(map.get(item).toString())+1); //將當前的投票項加1
}else{ //初始化一個保存投票信息的Map集合，並將選定投票項的投票數設置為1，其他為0
String[] arr={"基礎教程類","實例集錦類","經驗技巧類","速查手冊類","案例剖析類"};
map=new HashMap();
for(int i=0;i<arr.length;i++){
if(item.equals(arr[i])){ //判斷是否為選定的投票項
map.put(arr[i], 1);
}else{
map.put(arr[i], 0);
}
}
}
servletContext.setAttribute("pollResult", map); //保存投票結果到ServletContext對象中
response.setCharacterEncoding("GBK"); //設置響應的編碼方式，如果不設置彈出的對話框中的文字將亂碼
PrintWriter out=response.getWriter();
out.println("<script>alert('投票成功！');window.location.href='showResult.jsp';</script>");
}
}
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