配置管理-struts2把Action配成login就報錯，配成其他的就不會，這是為何？

struts2把Action配成login就報錯，配成其他的就不會，這是為何？

jsp代碼，就是在body上加個表單，表單內容如下：

<form action="login.action" method="post">
        <table>
            <tr>
                <td>用戶名：</td>
                <td><input type="text" name="user.username"></td>
            </tr>
            <tr>
                <td>密碼：</td>
                <td><input type="password" name="user.password"></td>
            </tr>
            <tr>
                <td><input type="reset" value="重填"></td>
                <td><input type="submit" value="登錄"></td>
            </tr>
        </table>
    </form> 

然後是Action

 public class LoginAction extends ActionSupport
{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private User user;
    @Override
    public String execute() throws Exception 
    {
        if("zhangsan".equals(user.getUsername())&&"123".equals(user.getPassword()))
        {
            System.out.println("SUCCESS 結果");
            return SUCCESS;
        }

        else
        {
            System.out.println("error結果");
            return ERROR;
        }
    }

    public User getUser() {
        return user;
    }
    public void setUser(User user) {
        this.user = user;
    }   
}

再然後是struts2的XML文件：

 <?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
    <package name="default" extends="struts-default">
        <action name="login" class="com.action.LoginAction">
            <result name="success">/success.jsp</result>
            <result name="error">/error.jsp</result>
        </action>
    </package>
</struts>   

最後是一個javabean

 public class User implements Serializable
{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    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;
    }
}

error.jsp與success.jsp隨便寫就好，然後運行就一直報No result defined for action com.action.LoginAction and result 的錯誤，只要把struts.xml文件跟上面給出的jsp form裡的login改成其他任意名字，例如：hhh之後，就正常運行不再報錯。這是為何？求各位幫個忙解答下，感激不盡

最佳回答：

web.xml中struts配置的問題。祝好！

   <filter>
   <filter-name>struts2</filter-name>
   <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
  </filter>

  <filter-mapping>
   <filter-name>struts2</filter-name>
   <url-pattern>/*</url-pattern>
  </filter-mapping>