设计模式01观察者模式(java)

先发代码，有空来写内容。

observer1

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

//学生类(Student)继承Observable后变得可以被观察
class Student extends Observable{
    //属性
    private String name;
    private boolean isSleep = false;
    private boolean isLate = false;
    //构造函数
    public Student(){}
    public Student(String name){
        this.name = name;
    }
    //睡觉行为
    public void sleep(){
        System.out.println(name + " is sleeping");
        isSleep = true;
        setChanged();
        notifyObservers();
        
    }
    public String toString(){
        return name;
    }
}
//教师类(Teacher)实现Observer接口成为观察者
class Teacher implements Observer{
    @Override
    public void update(Observable o,Object arg){
            System.out.println("teacher: "+o+",wakeup!wakeup!");
    }
}
//班主任类(ClassHead)实现Observer接口成为观察者
class ClassHead implements Observer{
    @Override
    public void update(Observable o,Object arg){
            System.out.println("classHead: "+o+",cleanTheRoomAfterSchool");
    }
}
public class ObserverDemo{
    public static void main(String[] arguments){
        Student tom = new Student("Tom");
        tom.addObserver(new ClassHead());
        tom.addObserver(new Teacher());

        System.out.println("有 "+tom.countObservers()+" 个观察者在观察Tom");
        tom.sleep();
        
    }
}

 

 

observer2

import java.util.Map;
import java.util.HashMap;
import java.util.Observer;
import java.util.Observable;

//学生类(Student)继承Observable后变得可以被观察
class Student extends Observable{
    //属性
    private String name;
    private boolean isSleep = false;
    private boolean isLate = false;
    //构造函数
    public Student(){}
    public Student(String name){
        this.name = name;
    }
    //睡觉行为
    public void sleep(){
        System.out.println(name + " is sleeping");
        isSleep = true;
        setChanged();
        notifyObservers("sleep");
        
    }
    //迟到行为
    public void late(){
        System.out.println(name + " was lated");
        isLate = true;
        setChanged();
        notifyObservers("late");
    }
    public String toString(){
        return name;
    }
}
//教师类(Teacher)实现Observer接口成为观察者
class Teacher implements Observer{
    //参数arg作为key，该参数触发的回应作为value存储在Map中
    private Map<String,String> info = new HashMap<String,String>();
    public Teacher(){
        info.put("sleep",",wakeup!wakeup!");
        info.put("late",",come in.");
    }
    //添加键值对
    public boolean addSay(String k,String v){
        return info.put(k,v)==null?false:true;
    }
    @Override
    public void update(Observable o,Object arg){
            String say = info.get(arg);
            if(say == null){
                return;
            }
            System.out.println("teacher: "+o+say);
    }
}
//班主任类(ClassHead)实现Observer接口成为观察者
class ClassHead implements Observer{
    private Map<String,String> info = new HashMap<String,String>();
    public ClassHead(){
        info.put("sleep",",goOutWashBaFace");
        info.put("late",",cleanTheRoom!");
    }
    public boolean addSay(String k,String v){
        return info.put(k,v)==null?false:true;
    }
    @Override
    public void update(Observable o,Object arg){
            String say = info.get(arg);
            if(say == null){
                return;
            }
            System.out.println("classHead: "+o+say);
    }
}
public class ObserverDemo{
    public static void main(String[] arguments){
        Student tom = new Student("Tom");
        tom.addObserver(new ClassHead());
        tom.addObserver(new Teacher());

        System.out.println("有 "+tom.countObservers()+" 个观察者在观察Tom");
        tom.sleep();
        tom.late();
    }
}

 Observer与Obvsevable实现

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
//定义observer接口
interface observer{
    public void update(observable o,Object arg);
}
//定义observable类
class observable{
    //isChanged记录实例是否改变
    private boolean isChanged;
    //obsers存储观察者集合
    private List<observer> obsers;
    //构造函数初始化实例
    public observable(){
        isChanged = false;
        obsers = new ArrayList<observer>();
    }
    //设置是否发生变化为false
    protected void clearChanged(){
        isChanged = false;
    }
    //设置是否发生变化为true
    public void setChanged(){
        isChanged = true;
    }
    //返回对象是否发生改变
    public boolean hasChanged(){
        return isChanged;
    }
    //添加观察者
    public void addObserver(observer o){
        obsers.add(o);
    }
    //删除指定观察者
    public void deleteObserver(observer o){
        obsers.remove(o);
    }
    //清空所有观察者
    public void deleteObservers(){
        obsers.clear();
    }
    //返回观察者数量
    public int countObservers(){
        return obsers.size();
    }
    
    //如果对象发生改变就通知所有观察者，然后将变化状态设置为false
    public void notifyObservers(){
        notifyObservers(new Object());
    }
    public void notifyObservers(Object arg){
        if(!hasChanged())
            return;
        Iterator it = obsers.iterator();
        while(it.hasNext()){
            ((observer)(it.next())).update(this,arg);
        }
        clearChanged();
    }
}