防表单重复提交
1、令牌生成器
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;
import sun.misc.BASE64Encoder;
public class TokenProccessor {
/*
*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 TokenProccessor(){}
private static final TokenProccessor instance = new TokenProccessor();
/**
* 返回类的对象
* @return
*/
public static TokenProccessor getInstance(){
return instance;
}
/**
* 生成Token
* Token：Nv6RRuGEVvmGjB+jimI/gw==
* @return
*/
public String makeToken(){ //checkException
// 7346734837483 834u938493493849384 43434384
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");
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);
}
}
}
2、把生成的令牌写到表单中
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 RefuseRepeatSubmit
*/
public class CreateRefuseRepeatSubmitTokenServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public CreateRefuseRepeatSubmitTokenServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String token = TokenProccessor.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
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
}
3、表单提交验证
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 RefuseRepeatSubmitServlet
*/
public class RefuseRepeatSubmitServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public RefuseRepeatSubmitServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
boolean b = isRepeatSubmit(request);// 判断用户是否是重复提交
if (b == true) {
System.out.println("请不要重复提交");
return;
}
request.getSession().removeAttribute("token");// 移除session中的token
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;
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}