如何使一个方法被称为被动之前调用一个方法 [英] How to make a method be called passive before invoke a method

问题描述

像这样：一类有一个叫做sayHello方法（）。上课的时候​​调用的sayHello（），在另一个类中的方法的实例的sayHello（）被调用之前被称为自动。

Like so : a class has a method called sayHello() . When a instance of the class call the sayHello(), a method in another class is called automatic before the sayHello() is called.

样品code可以是这样的：

the sample code can be like this:

public class Robot{
  public static void doSomethingBefore(){
       System.out.println("Do something before sayHello");
  }

}


public class Person {

     public void sayHello(){
           System.out.println("hello");
     }

     public static void main(String[] args){
             Person p = new Person();
             p.sayHello();
     }
}

输出结果：

Do something before sayHello
hello

看来它可以通过使用代理模式来完成。但我想它可以更简单。

It seems it can be done by using the proxy pattern. But I want it can be more simple.

使用注释：

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface MethodListener {
      public String className();
      public String methodName();
}

然后把方法的sayHello的MethodListener注释（）在Person类，

Then put the MethodListener annotation on the method sayHello() in the Person class,

public class Person {
  @MethodListener(className="Robot",methodName="doSomethingBefore")
  public void sayHello(){
       System.out.println("hello");
  }

  public static void main(String[] args){
         Person p = new Person();
         p.sayHello();
  }
 }

当其具有MethodListener注解的方法被调用，该方法doSomethingBefore（）被调用自动

When the method which has the MethodListener annotation be called, the method doSomethingBefore() is called automatic.

应该是可能的吗？如果是可以做到的，如何实现呢？

Should it be possible ？ If it can be done, how to achieve it?

推荐答案

我认为你正在寻找一个面向方面的编程框架如AspectJ时，JBoss AOP和Spring AOP的。

I think you are looking for an aspect-oriented programming framework such as AspectJ, JBoss AOP or Spring AOP.

由机器人法的人法的装修在施工Person实例的过程中发生的，但是你需要使用AOP的容器，而不是提供了一个工厂类新

The decoration of the Person method by the Robot method will happen during construction of the Person instance, but you will need to use a factory class provided by the AOP container instead of new.

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