Java设计模式之中介者模式(Mediator Pattern)简介

java设计模式的中介者模式是行为模式之一。定义一个中介对象来封装系列对象之间的交互。中介者使各个对象不需要显式地相互引用，从而使其耦合性松散，并且可以独立地改变他们之间的交互。

如下图所示：

生产者、消费者、代理商之间的中介模式实例：

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");
  }
}

运行结果：

hello! i am a consumer
i am a producer