我要评论本文实例讲述了java防止重复提交web表单的方法。分享给大家供大家参考，具体如下：
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 block
throw 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 block
e.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);
}
}
希望本文所述对大家java web程序设计有所帮助。
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