Struts2防止表单重复提交

防止表单重复提交主要用的到标签是<s: token />，拦截器 <interceptor-ref name="token" />，还有一个默认的返回值<result name="invalid.token">/input.jsp</result>  




在页面加载时，<s: token />产生一个GUID（Globally Unique Identifier，全局惟一标识符）值的隐藏输入框如：

<input type="hidden" name="struts.token.name" value="struts.token"/>
<input type="hidden" name="struts.token" value="BXPNNDG6BB11ZXHPI4E106CZ5K7VNMHR"/>

同时，将GUID放到会话（session）中；在执行action以前，“token”拦截器将会话token与请求token比较，若是二者相同，则将会话中的token删除并往下执行，不然向actionErrors加入错误信息。如此一来，若是用户经过某种手段提交了两次相同的请求，两个token就会不一样。

如下为action代码

import com.opensymphony.xwork2.ActionSupport;        
        
public class TestAction extends ActionSupport {                
         private static final long serialVersionUID = 6820659617470261780L;        
                
         private String message;        
                        
         public String getMessage() {        
                 return message;        
        }        
        
         public void setMessage(String message) {        
                 this.message = message;        
        }        
                
        @Override        
         public String execute() {        
                System.out.println( "Executing action, your message is " + message);        
                 return SUCCESS;        
        }                
}    

再看看JSP的写法

< %@ page language ="java" contentType ="text/html; charset=utf-8" pageEncoding ="utf-8" % >        
< %@ taglib prefix ="s" uri ="/struts-tags" % >        
        
< !DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >        
< html xmlns ="http://www.w3.org/1999/xhtml" >        
< head >        
         < title >struts2 test token </title>        
         < s:head />        
</head>        
< body >                
         < s:actionerror />        
         < s:form action ="testAction" >        
                 < s:textfield name ="message" label ="Message" />        
                 < s:token />     < %-- 注意这里--% >        
                 < s:submit />        
         </s:form>        
</body>        
</html>    

下面是struts2的配置文件

<? 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 ="test" extends ="struts-default" namespace ="/testToken" >        
                 < action name ="test" class ="com.fhx.TestAction" >        
                         < result name ="invalid.token" >/input.jsp </ result >                                                        
                         < result >/input.jsp </ result >        
        
                     < interceptor-ref name ="defaultStack" />        
                     < interceptor-ref name ="token" />        
        
                 </ action >        
         </ package >        
</ struts >    

 

以上XML片断值注意的是加入了“token”拦截器和“invalid.token”结果，由于“token”拦截器在会话token与请求token不一致时，将会直接返回“invalid.token”结果。