Spring AOP 代理模式学习

代理模式

代理是通知目标对象后创建的对象。从客户端的角度看，代理对象和目标对象是一样的。

静态代理

出租房屋

public interface Rent { 
    void Renthouse();
}

房东类

public class Host implements Rent {
    @Override
    public void Renthouse() {
        System.out.println("房东有一套房子出租!!!");
    }
}

代理类

public class Proxy implements Rent {
    private Host host;
    
    public Proxy(Host host) {
        this.host = host;
    }
    
    @Override
    public void Renthouse() {
        host.Renthouse();
        Money();
        seeHose();
        hetong();
    }
    
    public void Money() {
        System.out.println("中介-收取一定的报酬会");
    }
    
    public void seeHose() {
        System.out.println("中介-带我看房子。");
    }
    
    public void hetong() {
        System.out.println("满意的话，签合同！");
    }
}

测试类

public class client {
    public static void main(String[] args) {
        Host host = new Host();
        Proxy proxy = new Proxy(host);
        proxy.Renthouse();
    }
}

动态代理

动态代理分为三大类：基于接口（JDK动态代理）、基于类（CGLIB动态代理）、Java字节码实现（Javassist）。

动态代理实现案例

public interface Rent {
    void Rent();
}

public class Host implements Rent {
    @Override
    public void Rent() {
        System.out.println("房东有一整套房子出租!!!");
    }
}

public class ProxyInvocationHandler implements InvocationHandler {
    private Rent rent;
    public void setRent(Rent rent) {
        this.rent = rent;
    }
    public Object getProxy() {
        return Proxy.newProxyInstance(
            this.getClass().getClassLoader(),
            rent.getClass().getInterfaces(),
            this
        );
    }
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        return method.invoke(rent, args);
    }
}

public class client {
    public static void main(String[] args) {
        Host host = new Host();
        ProxyInvocationHandler pih = new ProxyInvocationHandler();
        pih.setRent(host);
        Rent proxy = (Rent) pih.getProxy();
        proxy.Rent();
    }
}