/**
* 天气主题（可观察者/目标）
* @author mjs
* @version 1.0.0
* @filename WeatherData.java
* @time 2017-3-9 下午8:26:48
* @copyright(C) 2017 **********有限公司
*/
package com.shing.design.observerpattern;
import java.util.Observable;
public class WeatherData extends Observable {
private float temperature; //温度
private float humidity; //湿度
private float pressure; //气压
public float getTemperature() {
return temperature;
}
public WeatherData() {
// TODO Auto-generated constructor stub
    }
/**
* 改变状态，通知观察者（布告板）
*/
public void measurementsChanged(){
setChanged();
notifyObservers();
}
/**
* 当气象台检测到变化是调用该方法
* @param temperature 温度
* @param humidity 湿度
* @param pressure 大气压
*/
public void setMeasurements(float temperature, float humidity, float pressure){
this.temperature = temperature;
this.humidity = humidity;
this.pressure = pressure;
measurementsChanged();
}
public void setTemperature(float temperature) {
this.temperature = temperature;
}
public float getHumidity() {
return humidity;
}
public void setHumidity(float humidity) {
this.humidity = humidity;
}
public float getPressure() {
return pressure;
}
public void setPressure(float pressure) {
this.pressure = pressure;
}
}

/**
* 显示要素
* @author mjs
* @version 1.0.0
* @filename DisplayElement.java
* @time 2017-3-9 下午8:24:49
* @copyright(C) 2017 **********有限公司
*/
package com.shing.design.observerpattern;
public interface DisplayElement {
/**
* 显示元素方法
*/
void display();
}

/**
* 目前状况布告板
* @author mjs
* @version 1.0.0
* @filename CurrentConditionsDisplay.java
* @time 2017-3-11 上午9:35:45
* @copyright(C) 2017 **********有限公司
*/
package com.shing.design.observerpattern;
import java.util.Observable;
import java.util.Observer;
public class CurrentConditionsDisplay implements Observer, DisplayElement {
Observable observable;
private float temperature;
private float humidity;
/**
* 初始化构造，并注册到气象台
* @param observable
*/
public CurrentConditionsDisplay(Observable observable) {
super();
this.observable = observable;
observable.addObserver(this);
}
/*
* 布告板显示
*/
public void display() {
// TODO Auto-generated method stub
System.out.println("【目前状况布告板】当前状况：" + temperature + "华摄氏度， " + humidity + "%湿度");
}
/*
*
*/
public void update(Observable obs, Object arg) {
if(obs instanceof WeatherData){
WeatherData weatherData = (WeatherData) obs;
this.temperature = weatherData.getTemperature();
this.humidity = weatherData.getHumidity();
display();
}
}
}

/**
* 预测布告板
* @author mjs
* @version 1.0.0
* @filename ForecastDisplay.java
* @time 2017-3-11 上午9:53:09
* @copyright(C) 2017 **********有限公司
*/
package com.shing.design.observerpattern;
import java.util.Observable;
import java.util.Observer;
public class ForecastDisplay implements DisplayElement, Observer {
Observable observable;
private float currentPressure = 29.92f;
private float lastPressure;
/**
* 初始化预测布告板，并注册在气象台
* @param observable
*/
public ForecastDisplay(Observable observable) {
super();
this.observable = observable;
observable.addObserver(this);
}
/*
* 更新状态
*/
public void update(Observable o, Object arg) {
// TODO Auto-generated method stub
if(o instanceof Observable){
WeatherData weatherData = (WeatherData) o;
lastPressure = currentPressure;
currentPressure = weatherData.getPressure();
display();
}
}
/*
*
*/
public void display() {
// TODO Auto-generated method stub
System.out.println("【预测布告板】当前气压:" + currentPressure + ",最新气压：" + lastPressure);
}
}

/**
* 测试类
* @author mjs
* @version 1.0.0
* @filename Test.java
* @time 2017-3-11 上午10:21:59
* @copyright(C) 2017 **********有限公司
*/
package com.shing.design.observerpattern;
public class Test {
public static void main(String[] args) {
WeatherData weatherDate = new WeatherData();
CurrentConditionsDisplay conditionsDisplay = new CurrentConditionsDisplay(weatherDate);
ForecastDisplay forecastDisplay = new ForecastDisplay(weatherDate);
weatherDate.setMeasurements(57, 87, 110);
}
}
/**
Console:
【预测布告板】当前气压:110.0,最新气压：29.92
【目前状况布告板】当前状况：57.0华摄氏度， 87.0%湿度
*/