通过接口注入获取Request，session，application

Action类

mport java.util.Map;

import org.apache.struts2.interceptor.ApplicationAware;
import org.apache.struts2.interceptor.RequestAware;
import org.apache.struts2.interceptor.SessionAware;
import org.sunxin.struts2.ch03.model.User;

import com.opensymphony.xwork2.Action;

public class LoginAction2 implements Action,RequestAware,SessionAware,ApplicationAware
{	
  private User user;
  private Map request;
  private Map session;
  private Map application;
  
  public User getUser()
  {
    return user;
  }

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

  @SuppressWarnings("unchecked")
  @Override
  public String execute() throws Exception
  {
    if("zhangsan".equals(user.getUsername()) && "1234".equals(user.getPassword()))
    { 
      //在请求中放置欢迎信息。
      request.put("greeting", "欢迎您来到程序员之家");
      
      //在session中保存user对象
      session.put("user", user);
      
      //统计用户访问量，在application中保存用户访问量数据
      Integer count = (Integer)application.get("counter");
      if(null == count)
        count=1;
      else
        count++;
      application.put("counter", count);
      
      return SUCCESS;
    }
    else
    {
      return ERROR;
    }
  }

  @Override
  public void setRequest(Map request)
  {
    this.request = request;
  }

  @Override
  public void setSession(Map session)
  {
    this.session = session;
  }

  @Override
  public void setApplication(Map application)
  {
    this.application = application;
  }
}