（java）从零开始之--观察者设计模式Observer

 1 /*
 2  * 气象台类
 3  * 
 4  */
 5 public class WeatherStation {
 6 
 7     private String[] weatherArr = {"大雨","大雪","台风","雾霾","多云","晴"};
 8     private String weatherDesc = weatherArr[0];
 9     private ArrayList<IWeather> list = new ArrayList<IWeather>();
10     
11     //对外提供一个方法添加天气预报更新时，要通知的对象
12     public void add(IWeather weather){
13         this.list.add(weather);
14     }
15     
16     //对外提供一个方法取消订阅天气预报
17     public void remove(IWeather weather){
18         if(weatherArr.length>0){
19             for (int i = 0; i < weatherArr.length; i++) {
20                 if(list.get(i).equals(weather)){
21                     this.list.remove(i);
22                     break;
23                 }
24             }
25             
26         }
27     }
28     
29     
30     //开始天气预报
31     public void startWeatherForecast(){
32         new Thread(){
33             @Override
34             public void run() {
35                 while(true){
36                     updateWeather();//每3秒钟更新一次天气预报 (模拟每天气象台自动更新天气预报)
37                     for (IWeather weather : list) {
38                         weather.updateWeather(weatherDesc);
39                     }
40                     try {
41                         Thread.sleep(3000);
42                     } catch (InterruptedException e) {
43                         e.printStackTrace();
44                     }
45                     
46                 }
47             }
48         }.start();
49         
50     }
51     
52     
53     //气象台更新天气
54     public void updateWeather(){
55         Random random = new Random();
56         int n = random.nextInt(weatherArr.length);
57         this.weatherDesc = weatherArr[n];
58         System.out.println("气象台发布天气预报："+this.weatherDesc);
59     }
60     
61 }

/*
 * 一个接口规范，实现了该接口对象所要做的动作。
 * 实现该接口的对象当气象台天气预报更新时执行
 * {"大雨","大雪","台风","雾霾","多云","晴"}
 */
public interface IWeather {
    public void updateWeather(String weatherDesc);
}

 1 /*
 2  * 可能订阅群个之一，工作者
 3  * 
 4  */
 5 public class Emp implements IWeather {
 6 
 7     String name;
 8     int age;
 9     
10     public Emp(String name, int age) {
11         this.name = name;
12         this.age = age;
13     }
14 
15     //{"大雨","大雪","台风","雾霾","多云","晴"}
16     @Override
17     public void updateWeather(String weatherDesc) {
18         System.out.println(this.name+":收到天气预报 "+weatherDesc);
19     }
20 }

/*
 * 可能订阅群体之一， 学生
 */
public class Student implements IWeather {

    String name;
    int age;
    
    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    //{"大雨","大雪","台风","雾霾","多云","晴"}
    @Override
    public void updateWeather(String weatherDesc) {
        System.out.println(this.name+":收到天气预报 "+weatherDesc);
    }

}

 1 public class WeatherMain {
 2 
 3     public static void main(String[] args) {
 4         WeatherStation weatherStation = new WeatherStation();
 5 
 6         Student s1 = new Student("小明", 10);
 7         Student s2 = new Student("小美", 10);
 8         Emp e1 = new Emp("大明", 10);
 9         Emp e2 = new Emp("大美", 10);
10         weatherStation.add(s1);
11         weatherStation.add(s2);
12         weatherStation.add(e1);
13         weatherStation.add(e2);
14         weatherStation.remove(e2);
15         weatherStation.startWeatherForecast();
16     }
17 
18 }