Java設計模式之中介者模式(Mediator Pattern)簡介

2019-11-26 15:28:01

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Java設計模式的中介者模式是行為模式之一。定義一個中介對象來封裝系列對象之間的交互。中介者使各個對象不需要顯式地相互引用，從而使其耦合性松散，并且可以獨立地改變他們之間的交互。

如下圖所示：

生產者、消費者、代理商之間的中介模式實例：

public abstract class PersonColleague{  protected Mediator mediator;  public Mediator getMediator()  {    return mediator;  }  public void setMediator(final Mediator mediator)  {    this.mediator = mediator;  }  protected abstract void message(String context);}public class Mediator{  private PersonColleague consumer = null;  private ProducerColleague producer = null;  public ProducerColleague getProducer()  {    return producer;  }  public void setProducer(final ProducerColleague producer)  {    this.producer = producer;  }  public PersonColleague getConsumer()  {    return consumer;  }  public void setConsumer(final PersonColleague consumer)  {    this.consumer = consumer;  }  public Mediator()  {  }  public synchronized void message(final String context)  {    if (consumer != null)    {      System.out.println(context);    }    else if (producer != null)    {      System.out.println(context);    }  }}public class ConsumerColleague extends PersonColleague{  public ConsumerColleague(final Mediator mediator)  {    this.mediator = mediator;  }  @Override  protected void message(final String context)  {    this.mediator.setConsumer(this);    this.mediator.message("hello! i am a consumer");  }}public class ProducerColleague extends PersonColleague{  public ProducerColleague(final Mediator mediator)  {    this.mediator = mediator;  }  @Override  protected void message(final String context)  {    this.mediator.setProducer(this);    this.mediator.message(context);  }}public class Client{  public static void main(final String[] args)  {    final Mediator mediator = new Mediator();    final PersonColleague person = new ConsumerColleague(mediator);    final PersonColleague person1 = new ProducerColleague(mediator);    person.message("I am a consumer");    person1.message("I am a producer");  }}

運行結果：