客户端防表单重复提交和服务器端session防表单重复提交

来源：互联网发布：淘宝收藏夹2000不够用编辑：程序博客网时间：2024/06/08 06:03

package cn.itcast.from;

import java.io.IOException;
import java.io.PrintWriter;
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;

import com.sun.org.apache.xml.internal.serializer.ToUnknownStream;

public class FromServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

//产生随机数（表单号）
TokenProcessor tp = TokenProcessor.getInstance();
String token = tp.generateToken();

request.getSession().setAttribute("token", token);

request.getRequestDispatcher("/form1.jsp").forward(request, response);

}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

doGet(request, response);
}

}

class TokenProcessor{ //令牌

/*
* 1.把构造方法私有
* 2.对外暴露一个方法
* 对外暴露一个方法，允许获取上面创建的对象
* 3.对外暴露一个方法，语序获取上面创建的对象
*/
private TokenProcessor(){}
private static final TokenProcessor instance = new 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();//在api中找不到
return encoder.encode(md5);

} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}

}

}

package cn.itcast.from;

import java.io.IOException;
import java.io.PrintWriter;

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 {
/*
String username = request.getParameter("username");

try {
Thread.sleep(1000*3);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("向数据库注册用户");
*/
boolean b = isTokenValid(request);
if(!b){
System.out.println("请不要重复提交");
}

request.removeAttribute("token");
System.out.println("向数据库注册用户");
}

//判断表单号是否有效
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;
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

doGet(request, response);
}

}

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