Struts2 Action动态方法调用问题

<%@ page contentType="text/html;charset=utf-8" language="java" %>

<%@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>

    <title><s:text name="loginPage"/></title>

</head>

<body>

<s:form action="login" method="POST" >

    <s:textfield name="username" key="user"/>

    <s:textfield name="password" key="pass"/>

    <s:submit value="登入"/>

    <input type="submit" value="注册" onclick="regist();"/>

    </s:form >

<script type="javascript">

    function regist(){

        targetForm=document.forms[0];

        targetForm.action="login!regist";

    }

</script>



</body>

</html>

package lee;

import com.opensymphony.xwork2.ActionContext;

import com.opensymphony.xwork2.ActionSupport;

/**

 * Created by Administrator on 2017/4/25 0025.

 */

public class LoginAction  extends ActionSupport{

    private String username;

    private String password;



    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;

    }

    public String regist() throws  Exception{

        ActionContext actionContext=ActionContext.getContext();

        actionContext.getSession().put("username",getUsername());

        actionContext.put("tip","恭喜你"+getUsername()+"。注册成功!");

        return SUCCESS;

    }

    @Override

    public String execute() throws Exception {

        if (getUsername().equals("xiao")

            &getPassword().equals("123456")){

            ActionContext.getContext().getSession().put("user",getUsername());

            return  SUCCESS;

        }

        else {

            return ERROR;

        }

    }



}

<?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>

    <constant name="struts.custom.i18n.resources" value="mess"/>

    <constant name="struts.i18n.encoding"  value="UTF-8"/>

    <constant name="struts.enable.DynamicMethodInvocation" value="true"></constant>

    <package name="lee" extends="struts-default" namespace="/">

        <action name="login" class="lee.LoginAction" >

            <result name="input">/login.jsp</result>

            <result name="error">/error.jsp</result>

            <result name="success">/welcome.jsp</result>

        </action>

        <action name="login2" class="lee.LoginAction2" >

            <result name="error">/error.jsp</result>

            <result name="success">/welcome.jsp</result>

        </action>

    </package>

</struts>