使用泛型简化动态代理

说明

1. 本文适合对动态代理有最最基本了解的人，可参看AOP的底层实现-CGLIB动态代理和JDK动态代理。
2. 本文目的在于简化动态代理的调用

maven依赖

    
        cglib
        cglib
        3.2.5
    

类图

代码

Shape

public interface Shape {
    void draw();
}

Circle

public class Circle implements Shape{
    @Override
    public void draw() {
        System.out.println("我是一个圆~");
    }
}

Square

public class Square implements Shape{
    @Override
    public void draw() {
        System.out.println("我是一个四方形~");
    }
}

DynamicProxy

public interface DynamicProxy {
    T bind();
}

JDKDynamicProxy

public class JDKDynamicProxy implements DynamicProxy, InvocationHandler {
    public JDKDynamicProxy(T t) {
        this.t = t;
    }

    private T t;

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("method " + method.getName() + " begin");
        method.invoke(t, args);
        System.out.println("method " + method.getName() + " end");
        return null;
    }

    @Override
    public T bind() {
        return (T) Proxy.newProxyInstance(t.getClass().getClassLoader(), t.getClass().getInterfaces(), this);
    }
}

CGLibDynamicProxy

public class CGLibDynamicProxy implements DynamicProxy, MethodInterceptor {
    private T t;

    public CGLibDynamicProxy(T t) {
        this.t = t;
    }

    public T bind() {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(t.getClass());
        enhancer.setCallback(this);
        T t = (T) enhancer.create();
        return t;
    }

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        System.out.println("method " + method.getName() + " begin");
//        methodProxy.invokeSuper(o, objects);
        method.invoke(t,objects);
        System.out.println("method " + method.getName() + " end");
        return null;
    }
}

Demo

public class Demo {
    public static void main(String[] args) {

        Shape shape = new Circle();
        CGLibDynamicProxy cgLibDynamicProxy = new CGLibDynamicProxy<>(shape);
        cgLibDynamicProxy.bind().draw();

        shape = new Square();
        JDKDynamicProxy jdkDynamicProxy = new JDKDynamicProxy<>(shape);
        jdkDynamicProxy.bind().draw();
    }
}

运行结果

注意

cglib中使用methodProxy和method可以达到同样的效果，但是所调参数不一样，否则会报错，具体原因无意深究，会用即可。