场景：
系统比较繁忙，存在延时
模拟延迟5s钟，用户点了一次提交，没反应，又点了一次提交，
这样会造成重复提交；
com.cy.action.StudentAction.java:
package com.cy.action;
import java.io.File;
import org.apache.commons.io.FileUtils;
import com.cy.model.Student;
import com.opensymphony.xwork2.ActionSupport;
public class StudentAction extends ActionSupport{
private static final long serialVersionUID = 1L;
private Student student;
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
public String add() throws Exception {
System.out.println("开始添加学生："+student);
Thread.sleep(5000);
System.out.println(student.getName()+"添加完成");
return SUCCESS;
}
}
struts.xml:
<struts>
<package name="manage" extends="struts-default">
<action name="student" class="com.cy.action.StudentAction" method="add">
<result name="success">/success.jsp</result>
</action>
</package>
</struts>
student.jsp:
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="student" method="post" >
姓名：<input type="text" name="student.name"/><br/>
年龄：<input type="text" name="student.age"/><br/>
<input type="submit" value="提交"/>
</form>
</body>
</html>
测试：
两次点击提交
二、使用<s:token/>标签防重复提交
struts.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<package name="manage" extends="struts-default">
<action name="student" class="com.cy.action.StudentAction" method="add">
<result name="success">/success.jsp</result>
<result name="invalid.token">/student.jsp</result>
<interceptor-ref name="token"></interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
</action>
</package>
</struts>
student.jsp修改为如下：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<!-- 重复提交的错误信息显示在这里 -->
<s:actionerror/>
<form action="student" method="post" >
<!-- s:token的存在，让每次提交都有唯一的一个token令牌
到了struts.xml中的<interceptor-ref name="token">token拦截器，就会识别
比如说第一次提交的时候，肯定有一个标识记录在session里面，假如用户手贱又点了一次的话，
form中token的值还是一样的，<interceptor-ref name="token">发现又来了这个玩意，肯定是重复提交。
会返回一个<result name="invalid.token">，将错误信息返回到student.jsp里面。
-->
<s:token></s:token>
姓名：<input type="text" name="student.name"/><br/>
年龄：<input type="text" name="student.age"/><br/>
<input type="submit" value="提交"/>
</form>
</body>
</html>
测试：
填写姓名和年龄，点击两次提交，发现界面提示信息：
后台正常执行，只添加一条，后台打印输出
上面有个不好的地方就是：将重复提交的错误信息，返回到界面了。
但是有这种需求：将重复提交的忽略；无视重复提交的请求；
三、使用tokenSession 拦截器防重复提交 -- 这种方式挺好的。
com.cy.action.StudentAction.java:
package com.cy.action;
import com.cy.model.Student;
import com.opensymphony.xwork2.ActionSupport;
public class StudentAction extends ActionSupport{
private static final long serialVersionUID = 1L;
private Student student;
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
public String add() throws Exception {
System.out.println("开始添加学生："+student);
Thread.sleep(5000);
System.out.println(student.getName()+"添加完成");
return SUCCESS;
}
}
struts.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<package name="manage" extends="struts-default">
<action name="student" class="com.cy.action.StudentAction" method="add">
<result name="success">/success.jsp</result>
<!-- <result name="invalid.token">/student.jsp</result>
<interceptor-ref name="token"></interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref> -->
<interceptor-ref name="tokenSession"></interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
</action>
</package>
</struts>
student.jsp:
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="student" method="post" >
<s:token></s:token>
姓名：<input type="text" name="student.name"/><br/>
年龄：<input type="text" name="student.age"/><br/>
<input type="submit" value="提交"/>
</form>
</body>
</html>
测试：
前台显示添加成功