Java代理和动态代理

code from 《Thinking in java》

代理模式

interface Interface {

    void doSomething();

    void somethingElse(String arg);

}

class RealObject implements Interface {

    @Override

    public void doSomething() {

        System.out.println("doSomething.");

    }

    @Override

    public void somethingElse(String arg) {

        System.out.println("somethingElse " + arg);

    }

}

class SimpleProxy implements Interface {

    private Interface proxy;

    public SimpleProxy(Interface proxy) {

        this.proxy = proxy;

    }

    @Override

    public void doSomething() {

        System.out.println("SimpleProxy doSomething.");

        proxy.doSomething();

    }

    @Override

    public void somethingElse(String arg) {

        System.out.println("SimpleProxy somethingElse " + arg);

        proxy.somethingElse(arg);

    }

}

public class SimpleProxyDemo {

    public static void consumer(Interface iface) {

        iface.doSomething();

        iface.somethingElse("bonobo");

    }

    public static void main(String[] args) {

        consumer(new RealObject());

        consumer(new SimpleProxy(new RealObject()));

    }

}

输出：

doSomething.
somethingElse bonobo
SimpleProxy doSomething.
doSomething.
SimpleProxy somethingElse bonobo
somethingElse bonobo

动态代理

class DynamicProxyHandler implements InvocationHandler {

    private Object proxy;

    public DynamicProxyHandler(Object proxy) {

        this.proxy = proxy;

    }

    @Override

    public Object invoke(Object proxy, Method method, Object[] args)

            throws Throwable {

        System.out.println("*** proxy: " + proxy.getClass() +

                ". method: " + method + ". args: " + args);

        if(args != null) {

            for(Object arg : args)

                System.out.println(" " + arg);

        }

        return method.invoke(this.proxy, args);

    }

}

public class SimpleDynamicProxy {

    public static void consumer(Interface iface) {

        iface.doSomething();

        iface.somethingElse("bonobo");

    }

    public static void main(String[] args) {

        RealObject real = new RealObject();

        consumer(real);

        // insert a proxy and call again:

        Interface proxy = (Interface)Proxy.newProxyInstance(

                Interface.class.getClassLoader(),

                new Class[]{ Interface.class },

                new DynamicProxyHandler(real));

        consumer(proxy);

    }

}

输出：

doSomething.
somethingElse bonobo
*** proxy: class typeinfo.\$Proxy0. method: public abstract void typeinfo.Interface.doSomething(). args: null
doSomething.
*** proxy: class typeinfo.\$Proxy0. method: public abstract void typeinfo.Interface.somethingElse(java.lang.String). args: [Ljava.lang.Object;@6a8814e9
bonobo
somethingElse bonobo

二者最大的区别动态代理将代理类和实际执行类解耦了

代理类持有的是Object类型的引用也就是说此时该代理类可以代理不同类型的实际执行类

只需要在客户端实例化不同的实际执行类再传入代理类中即可

key thinking ：解耦

巴特西

Java代理和动态代理

最新文章

热门文章