java动态代理实例

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class ProxyTest {

    public static void main(String[] args) {
        Target target = (Target)Proxy.newProxyInstance(TargetImpl.class.getClassLoader(), TargetImpl.class.getInterfaces(), new MyInterceptor());
        target.say();
        /*
         Console:
            拦截之前
            this is Target.class
            拦截之后
         */
    }
}

//目标类接口
interface Target {

    void say();
}

//目标类
class TargetImpl implements Target {

    @Override
    public void say() {
        System.out.println("this is Target.class");
    }

}

//拦截器
class MyInterceptor implements InvocationHandler {

    private Object target = new TargetImpl();
    
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("拦截之前");
        method.invoke(target, args);//调用目标类方法
        System.out.println("拦截之后");
        return null;
    }
}