struts2.x依赖注入无效的问题

package com.loginCheck;

import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport {
private String userName=null;
private String userPassword=null;


@Override
public String execute(){
if(userName != null) {
if(userName.equals("wuyanxue")) {

return SUCCESS;
}
}
System.out.println(userName+" "+userPassword);
return ERROR;
}

public void setUserName(String userName) {
this.userName = userName;
}

public String getUserName() {
return userName;
}

public void setUserPassword(String userPassword) {
this.userPassword = userPassword;
}

public String getUserPassword() {
return userPassword;
}

}

这是Action类

----------------------------------------

这是jsp页面的表单

<s:form action="login?request_locale=en_US" method="get">
<s:textfield name="userName" key="loginUserName" ></s:textfield>
<s:password name="userPassword" key="loginUserPassword" ></s:password>
<s:submit key="submit"></s:submit>
</s:form>

----------------------------------------


这是struts.xml的配置

<struts>
 
<constant name="struts.devMode" value="true" />
<constant name="struts.custom.i18n.resources" value="myResources"></constant>


<package name="example" namespace="" extends="struts-default">
<global-exception-mappings>
<exception-mapping result="Exception" exception="java.lang.Exception">
</exception-mapping>
</global-exception-mappings>
<action name="login" class="com.loginCheck.LoginAction">
            <interceptor-ref name="logger" />
            <interceptor-ref name="timer" />
        <exception-mapping result="SQLException" exception="java.sql.SQLException"></exception-mapping>
            <result name="success">
            /loginSuccess.jsp
            </result>
            <result name="error">
            /loginFail.jsp
            </result>
        </action>

    </package>

</struts>

--------------------------

问题描述: 当我在jsp页面表单中输入账号“wuyanxue”密码任意的时候 控制台输出null null

这说明struts2.x并未用jsp表单的值实例化LoginAction


问题究竟出在什么地方,是我的代码哪儿有问题吗？

struts2.x依赖注入
[解决办法]
还需要添加：

 <interceptor-ref name="defaultStack">  
                <param name="exception.logEnabled">true</param>  
                <param name="exception.logLevel">ERROR</param>  
            </interceptor-ref> 

http://www.iteye.com/problems/89992