代理模式

代理模式2011-10-01天堂露珠

  package pattern.proxy;
  /**
  * 代理模式:Proxy Pattern
  * @version 2009-6-27
  * @author Winty（wintys@gmail.com）
  */
  public class ProxyTest{
    public static void main（String[] args）{
        Subject subject;
        subject = new ProxySubject（）;
        subject.request （）;
    }
  }
  /**
  * 抽象主题角色
  */
  abstract class Subject{
    public abstract void request（）;
  }
  /**
  * 真实主题角色 
  */
  class RealSubject extends Subject{
    @Override
    public void request（）{
        System.out.println（"do request."）;
    }
  }
  /**
  * 代理主题角色
  */
  class ProxySubject extends Subject{
    private RealSubject realSubject;
    
    private void preRequest（）{
        System.out.println（"do preRequest"）;
    }
    public void request（） {
        preRequest（）;
        if（realSubject == null）{
             realSubject = new RealSubject（）;
        }
         realSubject.request（）;
        postRequest（）;
    }
    private void postRequest（）{
        System.out.println（"do postRequest"）;
    }
  }

运行结果:

do preRequest

do request.

do postRequest