struts2于validate要使用

package com.test.action;

import com.opensymphony.xwork2.ActionSupport;
import com.test.model.User;

public class CheckUser extends ActionSupport{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	
	private User user=new User();
	private String username;
	public String getUsername() {
		return username;
	}


	public void setUsername(String username) {
		this.username = username;
	}


	public String getPassword() {
		return password;
	}


	public void setPassword(String password) {
		this.password = password;
	}


	private String password;

	@Override
	public String execute() throws Exception {
		System.out.println("checkuser");
		// TODO Auto-generated method stub
		
		
		return SUCCESS;
	}


	/*注意，validate方法是在execute之前运行*/
	@Override
	public void validate() {
		user.setUsername(this.getUsername());
		user.setPassword(this.getPassword());
		System.out.println(user);
		// TODO Auto-generated method stub
		if(user.getUsername().equals("admin"))
		{
			this.addFieldError("username_error", "权限不够");
		}
		super.validate();
	}
	

}

struts.xml

<?xml version="1.0" encoding="UTF-8" ?
>
<!DOCTYPE struts PUBLIC
	"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
	"http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>

    
  <!--   採用注解的方式 -->
  
  	<constant name="struts.enable.DynamicMethodInvocation" value="true" />
    <constant name="struts.devMode" value="true" /> 

    <package name="default" namespace="" extends="struts-default">
        <!-- struts2捕获action类异常 -->
        <!-- <global-results>
			<result name="error">/error.jsp</result>
		</global-results>
		<global-exception-mappings>
			<exception-mapping result="error" exception="java.lang.Exception"></exception-mapping>
		</global-exception-mappings> -->
    	<action name="link" class="com.test.action.LoginAction">
    	    <result>/result.jsp</result>
    	</action>
    	<action name="linkIOC" class="com.test.action.LoginActionIOC">
    	    <result>/result.jsp</result>
    	</action>
    	<!-- 正确和错误的分别跳转，齐总input是在验证失败后会跳转的页面 -->
    	<action name="data" class="com.test.action.CheckUser">
    	     <result name="success">/result.jsp</result>
    	    <result name="input">/login.jsp</result>
    	</action>
    </package>

   
    <!-- Add packages here -->

</struts>

html页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="/struts-tags" prefix="s"%>

<!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>
<!-- 这个地方是用来显示错误信息 -->
<s:fielderror/>
<form action="data.action" method="post">
<input type="text" name="username"><br>
<input type="password" name="password"><br>
<input type="submit" name="ok"><br>
</form>
</body>
</html>

即当严重不通过后，会返回到该页面，同一时候输出出错信息。

測试结果。当输入admin之后。会发现例如以下的页面