代理模式

静态代理略过，哈哈

主要来说动态代理

1、jdk实现的动态代理

有两个主要类，一个是Proxy，一个是InvocationHandler

public interface UserService {

	public void add();
	public void delete();
}

public class UserServiceImpl implements UserService {

	@Override
	public void add() {
		System.out.println("执行了add方法");
	}

	@Override
	public void delete() {
		System.out.println("执行了delete方法");
	}
}

public class ProxyInvocationHandler implements InvocationHandler {
	
	//被代理的真实对象
	private Object target;

	public void setTarget(Object target) {
		this.target = target;
	}
	
	//生成得到代理类
	public Object getProxy(){
		return Proxy.newProxyInstance(this.getClass().getClassLoader(), 
				target.getClass().getInterfaces(), this);
	}

	@Override
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable {
		beforeLog(method.getName());
		Object result = method.invoke(target, args);
		afterLog(method.getName());
		return result;
	}
	
	public void beforeLog(String methodName){
		System.out.println("开始执行【" + methodName + "】方法。");
	}
	public void afterLog(String methodName){
		System.out.println("执行了【" + methodName + "】方法结束。");
	}
}

public class Client {

	public static void main(String[] args) {
		UserServiceImpl userServiceImpl = new UserServiceImpl();
		ProxyInvocationHandler invocationHandler = new ProxyInvocationHandler();
		invocationHandler.setTarget(userServiceImpl);
		UserService proxy = (UserService) invocationHandler.getProxy();
		proxy.add();
	}
}

输出结果

2、cglib实现的动态代理

引入依赖

<dependency>
    <groupId>cglib</groupId>
    <artifactId>cglib</artifactId>
    <version>3.3.0</version>
</dependency>
<dependency>
    <groupId>org.ow2.asm</groupId>
    <artifactId>asm</artifactId>
    <version>7.1</version>
</dependency>

public class CglibProxy implements MethodInterceptor{

	private Object target;
	
	public Object getInstance(final Object target){
		this.target = target;
		Enhancer enhancer = new Enhancer();
		enhancer.setSuperclass(this.target.getClass());
		enhancer.setCallback(this);
		return enhancer.create();
	}
	
	@Override
	public Object intercept(Object object, Method method, Object[] args,
			MethodProxy proxy) throws Throwable {
		beforeLog(method.getName());
		Object result = method.invoke(target, args);
		afterLog(method.getName());
		return result;
	}
	public void beforeLog(String methodName){
		System.out.println("开始执行【" + methodName + "】方法。");
	}
	public void afterLog(String methodName){
		System.out.println("执行了【" + methodName + "】方法结束。");
	}
}

public class Client {

	public static void main(String[] args) {
		
		UserServiceImpl userServiceImpl = new UserServiceImpl();
		CglibProxy cglibProxy = new CglibProxy();
		UserService instance = (UserService) cglibProxy.getInstance(userServiceImpl);
		instance.add();
	}
}

输出结果