观察者模式

package com.engaworld.devise.observer;

import java.util.Observable;
import java.util.Observer;

import sun.awt.DisplayChangedListener;

public class CurrentConditionsDisplay implements Observer{
Observable observable;
private float temperature;
private float humidity;

public CurrentConditionsDisplay(Observable observable){
this.observable = observable;
observable.addObserver(this);
}
public void update(Observable o, Object arg) {
// TODO Auto-generated method stub
if(o instanceof WeatherData){
WeatherData weatherData = (WeatherData)o;
this.temperature = weatherData.getTemperature();
this.humidity = weatherData.getHumidity();
//
this.diaplay();
}
}
public void diaplay(){
System.out.println("Current conditions:"+temperature);
System.out.println("F degrees and humidity:"+humidity);
}
}
----------------------------------------------------
package com.engaworld.devise.observer;

import java.util.Observable;
public class WeatherData extends Observable{
private float temperature;
private float humidity;
private float pressure;

public WeatherData(){

}
public WeatherData(float temperature,float humidity,float pressure){
this.temperature = temperature;
this.humidity = humidity;
this.pressure = pressure;
}
public void measurementsChanged(){
setChanged();
notifyObservers();
}
public void setMeasurements(float temperature,float humidity,float pressure){
this.temperature = temperature;
this.humidity = humidity;
this.pressure = pressure;
measurementsChanged();
}
public float getTemperature(){
return temperature;
}
public float getHumidity(){
return humidity;
}
public float getPressure(){
return pressure;
}
}
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package com.engaworld.devise.observer;

public class WeatherStation {
public static void main(String[] args) {
// TODO Auto-generated method stub
WeatherData weatherData = new WeatherData();

CurrentConditionsDisplay currentConditionsDisplay = new CurrentConditionsDisplay(weatherData);

weatherData.setMeasurements(11, 21, 31);
weatherData.setMeasurements(12, 22, 32);
weatherData.setMeasurements(13, 23, 33);
}
}