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Java 使用Token令牌防止表单重复提交的步骤:
在下列情况下,服务器程序将拒绝处理用户提交的表单请求:
FromServlet.java
package com.bh.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.bh.util.TokenUtil;public class FormServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String token = TokenUtil.getInstance().makeToken();//创建令牌 System.out.println("在FormServlet中生成的token:"+token); request.getSession().setAttribute("token", token); //在服务器使用session保存token(令牌) request.getRequestDispatcher("/Form.jsp").forward(request, response);//跳转到form.jsp页面 } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); }}
TokenUtil.java
package com.bh.util;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.Random;import sun.misc.BASE64Encoder;/** * @author cyq * */public class TokenUtil { /* *单例设计模式(保证类的对象在内存中只有一个) *1、把类的构造函数私有 *2、自己创建一个类的对象 *3、对外提供一个公共的方法,返回类的对象 */ private TokenUtil(){ } private static final TokenUtil instance = new TokenUtil(); /** * 返回类的对象 * @return */ public static TokenUtil getInstance(){ return instance; } /** * 生成Token * Token:Nv6RRuGEVvmGjB+jimI/gw== * @return */ public String makeToken(){ String token = (System.currentTimeMillis() + new Random().nextInt(999999999)) + ""; //数据指纹 128位长 16个字节 md5 try { MessageDigest md = MessageDigest.getInstance("md5"); //对于给定数量的更新数据,digest 方法只能被调用一次。digest 方法被调用后,MessageDigest对象被重新设置成其初始状态。 byte md5[] = md.digest(token.getBytes()); //base64编码--任意二进制编码明文字符 adfsdfsdfsf BASE64Encoder encoder = new BASE64Encoder(); return encoder.encode(md5); } catch (NoSuchAlgorithmException e) { throw new RuntimeException(e); } }}
Form.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><% String path = request.getContextPath(); String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";%>Form.jsp
DoFormServlet.java
package com.bh.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class DoFormServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { boolean isRepeat = isRepeatSubmit(request);//判断用户是否是重复提交 if(isRepeat==true){ request.setAttribute("MSG", "请不要重复提交"); System.out.println("请不要重复提交"); request.getRequestDispatcher("/Msg.jsp").forward(request, response); return; } request.getSession().removeAttribute("token");//移除session中的token request.setAttribute("MSG","处理用户提交请求!!"); request.getRequestDispatcher("/Msg.jsp").forward(request, response); System.out.println("处理用户提交请求!!"); } /** * 判断客户端提交上来的令牌和服务器端生成的令牌是否一致 * @param request * @return * true 用户重复提交了表单 * false 用户没有重复提交表单 */ private boolean isRepeatSubmit(HttpServletRequest request) { String client_token = request.getParameter("token"); //1、如果用户提交的表单数据中没有token,则用户是重复提交了表单 if(client_token==null){ return true; } //取出存储在Session中的token String server_token = (String) request.getSession().getAttribute("token"); //2、如果当前用户的Session中不存在Token(令牌),则用户是重复提交了表单 if(server_token==null){ return true; } //3、存储在Session中的Token(令牌)与表单提交的Token(令牌)不同,则用户是重复提交了表单 if(!client_token.equals(server_token)){ return true; } return false; } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); }}
Msg.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%>result show ${MSG}
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