使用泛型简化动态代理

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说明

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。
本文目的在于简化动态代理的调用

maven依赖

    <dependency>        <groupId>cglib</groupId>        <artifactId>cglib</artifactId>        <version>3.2.5</version>    </dependency>

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> {    T bind();}

JDKDynamicProxy

public class JDKDynamicProxy<T> implements DynamicProxy<T>, 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<T> implements DynamicProxy<T>, 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<Shape> cgLibDynamicProxy = new CGLibDynamicProxy<>(shape);        cgLibDynamicProxy.bind().draw();        shape = new Square();        JDKDynamicProxy<Shape> 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。

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