Java设计模式之观察者模式详解

/**
 * @create: 2021/10/12
 * @author: Tony Stark
 */
public interface Observer {
    /**
     * 更新的方法
     * @param temperature  温度
     * @param pressure   气压
     * @param humidity    湿度
     */
    public void update(float temperature,float pressure,float humidity);
}

/**
 * 观察者模式
 * @create: 2021/10/12
 * @author: Tony Stark
 */
public interface Subject {
    /**
     * 注册观察者
     * @param o
     */
    public void registerObserver(Observer o);
    /**
     * 移除观察者
     * @param o
     */
    public void removeObserver(Observer o);
    /**
     * 通知观察者
     */
    public void notifyObservers();
}

/**
 * 类是核心
 * 1.包含最新的天气情况
 * 2.含有观察者集合，使用ArrayList集合管理
 * 3.当数据有更新时，就主动调用、arrayList中的观察者就可以看到最新的信息
 *
 * @create: 2021/10/12
 * @author: Tony Stark
 */
public class WeatherData implements Subject {
    private float temperature;
    private float pressure;
    private float humidity;
    //观察者集合
    private ArrayList<Observer> observers;
    public WeatherData() {
        observers = new ArrayList<Observer>();
    }
    public void setData(float temperature, float pressure, float humidity){
        this.temperature=temperature;
        this.pressure=pressure;
        this.humidity=humidity;
        dataChange();
    }
    @Override
    public void registerObserver(Observer o) {
        observers.add(o);
    }
    @Override
    public void removeObserver(Observer o) {
        if (observers.contains(o)) {
            observers.remove(o);
        }
    }
    public void dataChange(){
        notifyObservers();
    }
    /**
     * 遍历所有的观察者并通知
     */
    @Override
    public void notifyObservers() {
        for (int i = 0; i < observers.size(); i++) {
            observers.get(i).update(this.temperature,this.pressure,this.humidity);
        }
    }
    public float getTemperature() {
        return temperature;
    }
    public void setTemperature(float temperature) {
        this.temperature = temperature;
    }
    public float getPressure() {
        return pressure;
    }
    public void setPressure(float pressure) {
        this.pressure = pressure;
    }
    public float getHumidity() {
        return humidity;
    }
    public void setHumidity(float humidity) {
        this.humidity = humidity;
    }
    public ArrayList<Observer> getObservers() {
        return observers;
    }
    public void setObservers(ArrayList<Observer> observers) {
        this.observers = observers;
    }
}

**
 * @create: 2021/10/12
 * @author: Tony Stark
 */
public class CurrentConditions implements Observer{
    /**
     * 温度 气压  湿度
     */
    private float temperature;
    private float pressure;
    private float humidity;
    @Override
    public void  update(float temperature, float pressure, float humidity){
        this.temperature=temperature;
        this.pressure=pressure;
        this.humidity=humidity;
        display();
    }
    /**
     * 显示天气
     */
    public void display(){
        System.out.println("Today  mTemperature:"+temperature+"****");
        System.out.println("Today  mPressure:"+pressure+"****");
        System.out.println("Today  mHumidity:"+humidity+"****");
    }
}

/**
 * @create: 2021/10/12
 * @author: Tony Stark
 */
public class Client {
    public static void main(String[] args) {
        //创建WeatherData
        WeatherData weatherData = new WeatherData();
        //创建观察者
        CurrentConditions currentConditions = new CurrentConditions();
        //注册到weatherData
        weatherData.registerObserver(currentConditions);
        //测试通知各个1注册的观察者
        System.out.println("通知各个注册的观察者，看看信息");
        weatherData.setData(10f,100f,33.3f);
    }
}

/**
 * @create: 2021/10/12
 * @author: Tony Stark
 */
public class SinaSite  implements Observer{
    /**
     * 温度 气压  湿度
     */
    private float temperature;
    private float pressure;
    private float humidity;
    @Override
    public void  update(float temperature, float pressure, float humidity){
        this.temperature=temperature;
        this.pressure=pressure;
        this.humidity=humidity;
        display();
    }
    /**
     * 显示天气
     */
    public void display(){
        System.out.println("新浪网：Today  mTemperature:"+temperature+"****");
        System.out.println("新浪网：Today  mPressure:"+pressure+"****");
        System.out.println("新浪网：Today  mHumidity:"+humidity+"****");
    }
}

        SinaSite sinaSite = new SinaSite();
        //注册到weatherData
        weatherData.registerObserver(currentConditions);
        weatherData.registerObserver(sinaSite);