s2sh中action类 return SUCCESS 出现问题 "SUCCESS cannot be resolved"

[code="java"]
import java.util.Date;

import org.springframework.web.struts.ActionSupport;

import com.jvortex.j2eeblog.manager.ManagerManager;
import com.jvortex.j2eeblog.model.Manager;

public class ManagerAction extends ActionSupport {
private ManagerManager managerManager;
private int id;
private String name;
private String password;
private Integer num;
private Date regTime;
……//此处省去GET SET方法
public String checkLogin()throws Exception{
Manager manager=managerManager.checkLogin(this.name, this.password);
if(manager!=null){
return SUCCESS;
}else{
return INPUT;
}

}

}[/code]

[img]http://dl.iteye.com/upload/attachment/452609/cc905aa7-529f-3322-aaa0-b66eb89cd91a.jpeg[/img]

应该要implements Action接口

哥！ 能否多贴点出来？