JDK动态代理是基于接口的代理,下面举例说明
- 代理类:proxy,代理动作必须要基于一个proxy实例来执行
- 代理执行类:实现InvocationHandler,案例中是TestInvocationHandler
- 被代理类:基于接口的用户自己的方法,案例中是SayImpl
首先说明下InvocationHandler的invoke
public interface InvocationHandler {
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable;
}
proxy:方法基于哪个proxy实例来执行
method:执行proxy实例的哪个方法(proxy代理谁就执行谁的方法)
args:methed的入参
代码示例:
public interface Say {
void sayHello(String words);
}
public class SayImpl implements Say {
@Override
public void sayHello(String words) {
System.out.println("hello:" + words);
}
}
public class TestInvocationHandler implements InvocationHandler { private Object target;
public TestInvocationHandler(Object target) {
this.target=target;
} @Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println("invoke begin");
System.out.println("method :"+ method.getName()+" is invoked!");
method.invoke(target,args);
System.out.println("invoke end");
return null;
}
}
public static void main(String[] args) { TestInvocationHandler testInvocationHandler = new TestInvocationHandler(new SayImpl());
Say say = (Say)Proxy.newProxyInstance(SayImpl.class.getClassLoader(), SayImpl.class.getInterfaces(), testInvocationHandler );
say.sayHello("my dear");
}
执行结果:
invoke begin
method :sayHello is invoked!
hello:my dear
invoke end