callback callback mechanism

1. Significance of callback mechanism

A calls B's method and
B finishes executing and then calls Acallback() to tell A that I'm done executing

2. Classification of callback mechanism

The callback mechanism is divided into synchronous and asynchronous.
Asynchronous requires the participation of threads.

3. Realization of callback mechanism

4. Implementation of each function

Callimpl.java

//接口隐藏方法具体实现
public interface Callimpl {
    public void CallRun(CallService callService);
}

CallBody.java

//接口方法的实现
public class CallBody implements Callimpl{

    @Override
    public void CallRun(CallService callService){
        //回调函数功能的实现真正模块
        System.out.println("回调函数正在实现");
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("回调功能实现完成了");
        //回调函数实现完成告诉调用方我已经实现完成了
        callService.CallBack();
    }
}

CallService.java

public class CallService {

    public Callimpl callimpl = null;

    public CallService(Callimpl callimpl){
        this.callimpl = callimpl;
    }

    public void Execute(){
        System.out.println("去调用回调函数的实现");
        //去调用真正的实现
        callimpl.CallRun(CallService.this);
        System.out.println("回调函数执行完成了");
    }

    public void CallBack(){
        System.out.println("Callbody告诉告诉service已经执行完成了");
    }

}

Test.java

public class Test {
    public static void main(String[] args) {
        //新建一个接口的实现类
        Callimpl A_Body = new CallBody();
        //新建一个service类的对象
        CallService callService = new CallService(A_Body);
        //调用service对象的具体实现函数
        callService.Execute();
    }
}