代理模式

/**
 * 抽象角色，真实角色和代理角色都要实现的接口
 * @author marcopan
 */
public interface IAbstractSubject {

    // 代理对象和真实角色共有的方法，租房()
    public void rentHouse();
}

/**
 * 真实角色--房东
 * @author marcopan
 *
 */
public class RealSubject implements IAbstractSubject {

    @Override
    public void rentHouse() {
        System.out.println("rentHouse from RealSubject");
    }
}

package proxy.staticProxy;

/**
 * 代理角色，中介，含有真实角色的引用
 * @author marcopan
 * 代理角色做两件事：
 * 1. 关联真实角色对象
 * 2. 调用真实对象方法
 */
public class StaticProxySubject implements IAbstractSubject {
    // 含有真实角色的引用
    private RealSubject realSubject = null;

    public StaticProxySubject(RealSubject subject) {
        this.realSubject = subject;
    }

    @Override
    public void rentHouse() {
        realSubject.rentHouse();
    }
}

public class Client {
    public static void main(String[] args) {
        IAbstractSubject proxySubject = new StaticProxySubject(new RealSubject());
        proxySubject.rentHouse();
    }
}

/**
 * 抽象角色，真实角色和代理角色都要实现的接口
 * @author marcopan
 */
public interface IAbstractSubject {
   public void requestHouse1();
   public void requestHouse2();
}

/**
 * 真实角色--房东
 * @author marcopan
 */
public class RealSubject implements IAbstractSubject {
   @Override
   public void requestHouse1() {
      System.out.println("requestHouse1 from RealSubject");
   }
   
   @Override
   public void requestHouse2() {
      System.out.println("requestHouse2 from RealSubject");
   }
}

public class DynamicProxySubject implements InvocationHandler {
   private RealSubject realSubject = null;

   public DynamicProxySubject(RealSubject realObject) {
      this.realSubject = realObject;
   }

   @Override
   /**
    * proxy:指代理对象,com.sun.proxy.$Proxy0
    * method:指代的是我们所要调用真实对象的某个方法的Method对象
    * args:指代的是调用真实对象某个方法时接受的参数
    */
   public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
      method.invoke(realSubject, args);
      return null;
   }
}

public class Client {
   public static void main(String[] args) {
      RealSubject iSubject = new RealSubject();
      InvocationHandler handler = new DynamicProxySubject(iSubject); 
      
      /**
       * Proxy这个类的作用就是用来动态创建一个代理对象的类
       * Proxy.newProxyInstance返回的是一个代理对象:com.sun.proxy.$Proxy0
       * 根据handler.getClass().getClassLoader()和iSubject.getClass().
　　　　　　getInterfaces()构造Class对象，Class对象的构造函数入参是handler
       */
      IAbstractSubject proxySubject = (IAbstractSubject) Proxy.newProxyInstance(handler.getClass().getClassLoader(),
                                                              iSubject.getClass().getInterfaces(),
                                                              handler);
      System.out.println(proxySubject.getClass().getName());
      //调用的是super.h.invoke(this, , )，DynamicProxySubject的invoke方法
      proxySubject.requestHouse1();
      proxySubject.requestHouse2();
   }
}