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设计模式11---观察者模式
观察者模式实质就是提取：提取监听对象的过程是相同的，也就是说observer类为根据不同的subject的状态做出相应的反应。
package com.jayfulmath.designpattern.observer;public abstract class Observer { protected String name; protected ISubject sub; public Observer(String name, ISubject sub) { this.name = name; this.sub = sub; } public abstract void Update();}
public interface ISubject { public void Attach(Observer obs); public void Detach(Observer obs); public void Broadcast(); public String getSubjectStatus(); public void setSubjectStatus(String subjectStatus);}
public class NBALooker extends Observer {
public NBALooker(String name, ISubject sub) {
super(name, sub);
// TODO Auto-generated constructor stub
}
@Override
public void Update() {
System.out.println(sub.getSubjectStatus()+"\t"+name+"\tstop NBA Look");
}
}
public class NBALooker extends Observer { public NBALooker(String name, ISubject sub) { super(name, sub); // TODO Auto-generated constructor stub } @Override public void Update() { System.out.println(sub.getSubjectStatus()+"\t"+name+"\tstop NBA Look"); }}
public class StockLooker extends Observer { public StockLooker(String name, ISubject sub) { super(name, sub); // TODO Auto-generated constructor stub } @Override public void Update() { // TODO Auto-generated method stub System.out.println(sub.getSubjectStatus()+"\t"+name+"\tstop Stock Look"); }}
import java.util.ArrayList;import java.util.List;public class Boss implements ISubject { List<Observer> _mObservers = new ArrayList<Observer>(); public String subjectStatus; public void Attach(Observer obs) { _mObservers.add(obs); } public void Detach(Observer obs) { _mObservers.remove(obs); } public void Broadcast() { //here may be asynchronous to notify observer for(Observer observer :_mObservers) { observer.Update(); } } /** * @return the subjectStatus */ public String getSubjectStatus() { return subjectStatus; } /** * @param subjectStatus the subjectStatus to set */ public void setSubjectStatus(String subjectStatus) { this.subjectStatus = subjectStatus; }}
main:
public class ObserverMain extends BasicExample { @Override public void startDemo() { ISubject huhanshang = new Boss(); Observer maweidong = ObserverFactory.Factory("NBALooker", "maweidong", huhanshang); Observer zhangdashang = ObserverFactory.Factory("StockLooker", "zhangdashang", huhanshang); huhanshang.Attach(maweidong); huhanshang.Attach(zhangdashang); huhanshang.setSubjectStatus("I am back! Huhan Shang!"); huhanshang.Broadcast(); }}
设计模式11---观察者模式
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