JAVA Web防止表单重复提交实例
package cn.com.form;import java.io.IOException;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.Random;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import sun.misc.BASE64Encoder;//产生表单public class FormServlet extends HttpServlet {private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//产生随机数TokenProcessor tp=TokenProcessor.getInstance();String token=tp.generateToken();request.getSession().setAttribute("token", token);request.getRequestDispatcher("/form.jsp").forward(request, response);}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}}class TokenProcessor//令牌{/* * 1.把构造函数私有 * 2.自己创建一个 * 3.对外暴露一个方法，允许获取上面创建的对象 * */private static final TokenProcessor instance=new TokenProcessor();private TokenProcessor(){}public static TokenProcessor getInstance(){return instance;}public String generateToken(){String token=System.currentTimeMillis()+new Random().nextInt()+"";try {MessageDigest md=MessageDigest.getInstance("md5");byte[] md5=md.digest(token.getBytes());//base64编码BASE64Encoder encoder=new BASE64Encoder();return encoder.encode(md5);} catch (NoSuchAlgorithmException e) {// TODO Auto-generated catch blockthrow new RuntimeException(e);}}}<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%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>My JSP 'form.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">--> </head> <body> <form action="/Session/DoForm" method="post"> <input type="hidden" name="token" value="${token}"> 用户名：<input type="text" name="userName"> <input type="submit" value="提交"> </form> </body></html>package cn.com.form;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class DoForm * 处理表单提交的请求 * */public class DoForm extends HttpServlet {private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {/*String userName=request.getParameter("userName");try {Thread.sleep(1000*3);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println("向数据库提交注册用户...");*/boolean b=isTokenValid(request);if(!b){System.out.println("请不要重复提交！");return;}request.getSession().removeAttribute("token");System.out.println("向数据库中注册用户==");}private boolean isTokenValid(HttpServletRequest request) {String client_token=request.getParameter("token");if(client_token==null){return false;}String server_token=(String)request.getSession().getAttribute("token");if(server_token==null){return false;}if(!client_token.equals(server_token)){return false;}return true;}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}}