代码实践
原理类图
code
老师个大傻X,他tm起名和系统内置的Observer一样的接口,最后tm类导入乱了,傻B
改进方案 Observer => Observer2
Subject
package com.atguigu.observer.improve;
// 让这个WeathreData来实现
public interface Subject {
public void registerObserver(Observer2 o);
public void removeObserver(Observer2 o);
public void notifyObservers();
}
Observer
package com.atguigu.observer.improve;
/**
* ClassName: 观察者接口,由观察者来实现
*
* @project java_mode
* @package com.atguigu.observer.improve
*/
public interface Observer2 {
public void update(float temperature, float pressure, float humidity);
}
CurrentConditions
这个和前面的一样就行了
package com.atguigu.observer.improve;
import java.util.Observable;
import java.util.Observer;
/**
* ClassName: <br/>
* Description: <br/>
* Date: 2021-02-09 10:09 <br/>
* <br/>
*
* @author victor
* @project java_mode
* @package com.atguigu.observer.improve
*/
public class CurrentConditions implements Observer2 {
// 温度
private float temperature;
// 气压
private float pressure;
// 湿度
private float humidity;
// 更新天气情况 ,别人来调用,是由于WeatherData来调用,我使用退送模式
public void update(float temperature, float pressure, float humidity) {
this.temperature = temperature;
this.pressure = pressure;
this.humidity = humidity;
display();
}
// 显示
public void display() {
System.out.println("---Now mTemperature"+temperature+"---");
System.out.println("---Now mPressure"+pressure+"---");
System.out.println("---Now mhumidity"+humidity+"---");
}
}
WeatherData
package com.atguigu.observer.improve;
import java.util.ArrayList;
/**
* 类是核心
* 1. 包含最新的天气情况信息
* 2. 含有观察者集合,使用ArrayList管理
* 3. 当数据有更新时,就主动的调用ArrayList
* 通知所有的(接入方)就看到最新的信息
*
* @project java_mode
* @package com.atguigu.observer
*/
public class WeatherData implements Subject {
private float temperature; // 温度
private float pressure; // 气压
private float humidity; // 湿度
// 观察者集合
private ArrayList<Observer2> observers;
private CurrentConditions currentConditions;
public WeatherData() {
observers = new ArrayList<Observer2>();
}
public void dataChange() {
notifyObservers();
}
// 当数据由于更新的时候,就调用setData
public void setData(float temperature, float pressure, float humidity) {
this.temperature = temperature;
this.pressure = pressure;
this.humidity = humidity;
// 调用dataChange,将最新的信息推送给接入方 currentConditions
dataChange();
}
// 注册一个观察者
@Override
public void registerObserver(Observer2 o) {
observers.add(o);
}
// 移除一个观察者
@Override
public void removeObserver(Observer2 o) {
if (observers.contains(o)) {
observers.remove(o);
}
}
//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<Observer2> getObservers() {
return observers;
}
public void setObservers(ArrayList<Observer2> observers) {
this.observers = observers;
}
public CurrentConditions getCurrentConditions() {
return currentConditions;
}
public void setCurrentConditions(CurrentConditions currentConditions) {
this.currentConditions = currentConditions;
}
}
客户端
package com.atguigu.observer.improve;
/**
* ClassName: <br/>
* Description: <br/>
* Date: 2021-02-09 10:33 <br/>
* @author yufengming
* @project java_mode
* @package com.atguigu.observer.improve
*/
public class Client {
public static void main(String[] args) {
// 创建一个WeatherData
WeatherData weatherData = new WeatherData();
// 创建观察者
CurrentConditions currentConditions = new CurrentConditions();
// 注册到weatherData
weatherData.registerObserver(currentConditions);
//测试
System.out.println("通知各个观察者,看看信息");
weatherData.setData(10f,101f,20.3f);
/**
* 通知各个观察者,看看信息
* ---Now mTemperature10.0---
* ---Now mPressure101.0---
* ---Now mhumidity20.3---
*
* Process finished with exit code 0
*/
}
}
这样写的扩展性质就会十分好
比如:我现在要加一个百度(新的观察者)
百度
package com.atguigu.observer.improve;
/**
* ClassName: <br/>
* Description: <br/>
* Date: 2021-02-09 10:36 <br/>
* @author yufengming
* @project java_mode
* @package com.atguigu.observer.improve
*/
public class BaiduSite implements Observer2{
// 温度
private float temperature;
// 气压
private float pressure;
// 湿度
private float humidity;
// 更新天气情况 ,别人来调用,是由于WeatherData来调用,我使用退送模式
public void update(float temperature, float pressure, float humidity) {
this.temperature = temperature;
this.pressure = pressure;
this.humidity = humidity;
display();
}
// 显示
public void display() {
System.out.println("----baidu.com----");
System.out.println("---百度: mTemperature"+temperature+"---");
System.out.println("---百度: mPressure"+pressure+"---");
System.out.println("---百度: mhumidity"+humidity+"---");
}
}
客户端
package com.atguigu.observer.improve;
/**
* ClassName: <br/>
* Description: <br/>
* Date: 2021-02-09 10:33 <br/>
* @author yufengming
* @project java_mode
* @package com.atguigu.observer.improve
*/
public class Client {
public static void main(String[] args) {
// 创建一个WeatherData
WeatherData weatherData = new WeatherData();
// 创建观察者
CurrentConditions currentConditions = new CurrentConditions();
BaiduSite baiduSite = new BaiduSite();
// 注册到weatherData
weatherData.registerObserver(currentConditions);
weatherData.registerObserver(baiduSite);
//测试
System.out.println("通知各个观察者,看看信息");
weatherData.setData(10f,101f,20.3f);
/**
* 通知各个观察者,看看信息
* ---Now mTemperature10.0---
* ---Now mPressure101.0---
* ---Now mhumidity20.3---
* ----baidu.com----
* ---百度: mTemperature10.0---
* ---百度: mPressure101.0---
* ---百度: mhumidity20.3---
*
* Process finished with exit code 0
*/
}
}
这么写就很灵活,还可以去掉Current观察者,随时
