代理模式（静态\动态代理）

1、静态代理

      接口有几个方法，代理类则实现几个方法，代码冗余。

/**
 * 接口
 * @author YLJ
 *
 */
public interface Animal {
	public void say();
	public void sleep();
}
/**
 * 实现类,实现接口,实现方法
 * @author YLJ
 *
 */
class Dog implements Animal{
	@Override
	public void say() {
		System.out.println("dog say");
	}

	@Override
	public void sleep() {
		System.out.println("dog sleep");
		
	}
}
/**
 * 实现类,实现接口,实现方法
 * @author YLJ
 *
 */
class Cat implements Animal {

	@Override
	public void say() {
		System.out.println("cat say");
	}

	@Override
	public void sleep() {
		System.out.println("cay sleep");
	}
}
/**
 * 代理类,实现接口,实现方法（调用实际角色方法，并添加附加功能）
 * @author YLJ
 *
 */
class Proxy implements Animal {
	private Animal animal;
	public Proxy(Animal animal){
		this.animal = animal;
	}
	@Override
	public void say() {
		System.out.println("proxy say...");
		animal.say();
	}
	@Override
	public void sleep() {
		System.out.println("proxy sleep...");
		animal.sleep();
	}
}

    测试

/**
 * 测试类
 * @author YLJ
 *
 */
public class App {
	
	public static void main(String[] args) {
		Proxy dog = new Proxy(new Dog());
		dog.say();
		dog.sleep();
		Proxy cat = new Proxy(new Cat());
		cat.say();
		cat.sleep();
		
	}
}

2、动态代理

/**
 * 接口
 * @author YLJ
 *
 */
public interface Animal {
	void say();
	void sleep();
}
/**
 * 实现类
 * @author YLJ
 *
 */
class Dog implements Animal{
	private String name;
	public Dog(String name) {
		this.name = name;
	}
	public void say(){
		System.out.println(this.name + ": say。。。");
	}
	public void sleep() {
		System.out.println(this.name + ": say。。。");
	}
	
}
/**
 * 实现类
 * @author YLJ
 *
 */
class Cat implements Animal{
	private String name;
	public Cat(String name) {
		this.name = name;
	}
	public void say(){
		System.out.println(this.name + ": say。。。");
	}
	public void sleep() {
		System.out.println(this.name + ": say。。。");
	}
}

class AnimalHandler implements InvocationHandler{
	private Animal animal;
	public AnimalHandler(Animal animal) {
		this.animal = animal;
	}
	/**
	 * 核心方法，实现所有代理方法调用，
	 */
	@Override
	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
		System.out.println("proxy...");
		method.invoke(animal, args);
		return null;
	}

}

   测试

public static void main(String[] args) {
		Animal dog = new Dog("旺财");
		AnimalHandler dogHandler  = new AnimalHandler(dog);
		Animal d = (Animal)Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), new Class[]{Animal.class}, dogHandler);
		d.say();
		d.sleep();
		Animal cat = new Dog("猫咪");
		AnimalHandler catHandler  = new AnimalHandler(cat);
		Animal c = (Animal)Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), new Class[]{Animal.class}, catHandler);
		c.say();
		c.sleep();
		
	}