中介者模式

Posted 2022-12-11 yuanGrowing

一、作用：降低类与类之间的耦合程度，当A和B有双向的关系时，就产生了较强的耦合，这时候引入一个中介者的类，A与B都只和这个中介者类相关，由中介者类来控制A与B的关系，这样就完成了解耦。

二、例子：
有两种工人workera 和workerb，他们需要一起工作，如果不使用中介者模式，那么就需要两个类，WorkerA和WorkerB，他们之间相互依赖。使用中介者模式时，如下：
先定义一个抽象工作类：

public abstract class AbstractWorker 
 IMediator mediator ;
 public AbstractWorker(IMediator mediator) 
  this.mediator = mediator ;
 
 abstract void work();

WorkerA：

public class WorkerA extends AbstractWorker 
 public WorkerA(IMediator mediator) 
  super(mediator);
 
 @Override
 void work() 
  System.out.println("worka is working!");
 

WorkerB:

public class WorkerB extends AbstractWorker

 public WorkerB(IMediator mediator) 
  super(mediator);
 
 @Override
 void work() 
  System.out.println("workb is working");
 

IMediator接口:

public abstract class AbstractWorker 
 IMediator mediator ;
 public AbstractWorker(IMediator mediator) 
  this.mediator = mediator ;
 
 abstract void work();

Mediator实现类：

public class Mediator implements IMediator

 private WorkerA workera ;
 private WorkerB workerb ;

 @Override
 public void createWorkers(WorkerA workerA,WorkerB workerB) 
  this.workera = workerA ;
  this.workerb = workerB ;
 

 @Override
 public void beginWork() 
  this.workera.work();
  this.workerb.work();
 

测试类：

public class Test 
 public static void main(String[] args) 
  IMediator mediator = new Mediator();
  WorkerA workerA = new WorkerA(mediator);
  WorkerB workerB = new WorkerB(mediator);
  mediator.createWorkers(workerA, workerB);
  mediator.beginWork();
 

运行结果：
worka is working!
workb is working