使用中介者模式来集中相关对象之间复杂的沟通和控制方式。
示例—智能家居
智能屋中有闹钟、日历、咖啡壶、喷头。用户设置了以下命令
- 如果点击煮咖啡按钮，闹钟就会在5秒后告诉咖啡壶开始煮咖啡。
- 周末不要供应咖啡。
- 在洗澡前喷头自动开启，开始向澡盆灌水，50秒后自动关闭喷头。
- 在丢垃圾的日子，闹钟将提示。
UML图表示
中介者模式-智能家居
代码演示
事件接口（用于使用匿名内部类）
package Mediator;
public interface Event<T> {
void execute(T component);
}
闹钟类
package Mediator;
public class Alarm {
void alert(int delay, Event<Alarm> event){
try {
Thread.sleep(500);
System.out.println("Ringing.......");
if (delay > 0) System.out.print("It has passed " + delay + " seconds. ");
event.execute(this);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
咖啡壶类
package Mediator;
public class CoffeePot {
void boilCoffee(){
System.out.println("Boiling Coffee......");
}
}
日历类
package Mediator;
import java.util.Random;
public class Calendar {
Random random;
Calendar(){
random = new Random(47);
}
boolean isWeekend(){
int resultRandom = random.nextInt(10);
return resultRandom % 2 == 1;
}
boolean isTrashDay(){
int resultRandom = random.nextInt(10);
return resultRandom % 2 == 1;
}
}
喷头类
package Mediator;
public class Sprinkler {
void open(){
System.out.println("Opening sprinkler");
}
void close(){
System.out.println("Closing sprinkler");
}
}
中介者类
package Mediator;
public class Mediator {
private Alarm alarm;
private CoffeePot coffeePot;
private Sprinkler sprinkler;
private Calendar calendar;
Mediator(Alarm alarm,CoffeePot coffeePot,Sprinkler sprinkler, Calendar calendar){
this.alarm = alarm;
this.coffeePot = coffeePot;
this.sprinkler = sprinkler;
this.calendar = calendar;
}
void wannaCoffee(){
if (calendar.isWeekend()) {
System.out.println("It isn't supplied coffee on weekend.");
return;
}
alarm.alert(5, component -> coffeePot.boilCoffee());
}
void takeBath(){
sprinkler.open();
alarm.alert(50, component -> sprinkler.close());
}
void alertTrashDay(){
if (calendar.isTrashDay()) {
alarm.alert(0, component -> System.out.println("It's time to take out the trash"));
}
}
}
测试代码
package Mediator;
public class MediatorDriver {
public static void main(String[] args) {
Alarm alarm = new Alarm();
Calendar calendar = new Calendar();
CoffeePot coffeePot = new CoffeePot();
Sprinkler sprinkler = new Sprinkler();
Mediator mediator = new Mediator(alarm,coffeePot,sprinkler,calendar);
mediator.wannaCoffee();
mediator.takeBath();
mediator.alertTrashDay();
}
}
测试结果
Ringing.......
It has passed 5 seconds. Boiling Coffee......
Opening sprinkler
Ringing.......
It has passed 50 seconds. Closing sprinkler
Ringing.......
It's time to take out the trash
