观察者模式例子

看完观察者模式自己实现了一下.
我用的是推模式.
数据传入模型

package study;

public class WeatherDataModel {
	
	private String day ="";
	public WeatherDataModel(String day){
		this.setDay(day);
	}
	public String getDay() {
		return day;
	}

	public void setDay(String day) {
		this.day = day;
	}

}

主题,信息源,发布者

package study;

import java.util.Observable;

public class WeathereData extends Observable{
	public  void findData(WeatherDataModel dataModel){
		this.setChanged();
		this.notifyObservers(dataModel);
	}
	

}

观察者,订阅用户

package study;

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

public class CatObserver implements Observer{

	public void update(Observable o, Object arg) {
	
		if(arg instanceof WeatherDataModel){
			System.out.println(((WeatherDataModel)arg).getDay());
		}
		
	}

}

测试

package study;

import junit.framework.TestCase;

public class TestObserverPattern extends TestCase{
	public void testObserver() {
		WeatherDataModel newWeather = new WeatherDataModel(
				"Today is a good day");
		WeathereData weathereData = new WeathereData();
		CatObserver catObserver = new CatObserver();
		weathereData.addObserver(catObserver);
		//weathereData.
		weathereData.findData(newWeather);
		newWeather.setDay("It's a fine day");
		weathereData.findData(newWeather);
		weathereData.findData(newWeather);

	}

}

欢迎大家交流.