设计模式——JDK中的观察者模式

用JDK的中观察者模式实现对温度的监控。每两秒钟会去实时的监测环境的温度，环境温度低于35度时为正常温度，否则为异常温度，当连续监测超温达到临界值时，会向配置的邮箱发送警示邮件

public class Condition {

    //临界温度
    private int limitTemperature;
    //连续达到临界次数
    private int limitCount;
    //连续达到临界次数发送的邮件对象
    private String mail;

    public Condition() {
    }

    public Condition(int limitTemperature, int limitCount, String mail) {
        this.limitTemperature = limitTemperature;
        this.limitCount = limitCount;
        this.mail = mail;
    }

    public int getLimitTemperature() {
        return limitTemperature;
    }

    public void setLimitTemperature(int limitTemperature) {
        this.limitTemperature = limitTemperature;
    }

    public int getLimitCount() {
        return limitCount;
    }

    public void setLimitCount(int limitCount) {
        this.limitCount = limitCount;
    }

    public String getMail() {
        return mail;
    }

    public void setMail(String mail) {
        this.mail = mail;
    }

}

public class TemperatureSubject extends Observable {


    private  int randomTemperature;

    private Condition condition;


    public Condition getCondition() {
        return condition;
    }

    public void setCondition(Condition condition) {
        this.condition = condition;
    }


    public int getRandomTemperature() {
        return randomTemperature;
    }

    public void setRandomTemperature(int randomTemperature) {

        this.randomTemperature = randomTemperature;
        //更新数据
        setChanged();
        //将条件对象传递给各个观察者
        notifyObservers(condition);
    }
}

public class AbnormalTemperatureObserver  implements Observer {

    //默认临界次数为0
    private int qty=0;

    @Override
    public void update(Observable o, Object arg) {
        TemperatureSubject subject=(TemperatureSubject)o;
        Condition condition=(Condition)arg;

        if(subject.getRandomTemperature()>=condition.getLimitTemperature()){
            qty++;
            saveToDataBase(subject);
        }else{
            //未达到临界时，连续超温记录被中断，将临界次数归零
            qty=0;
            saveToDataBase(subject);
        }


        if(qty>=condition.getLimitCount()){
            sendMail(condition);
        }

    }


    
    public void saveToDataBase(TemperatureSubject subject){
        //模拟记录温度数值
        System.out.println("当前温度为"+subject.getRandomTemperature());
    }


    public void sendMail(Condition condition){
        System.out.println("发送邮件"+condition.getMail());
    }

}

public class NormalTemperatureObserver implements Observer {
    @Override
    public void update(Observable o, Object arg) {
        TemperatureSubject subject=(TemperatureSubject)o;
        Condition condition=(Condition)arg;
        if(subject.getRandomTemperature()
            //模拟记录温度数值
            System.out.println("当前温度为"+subject.getRandomTemperature());
        }
    }
}

public class Main {
    private static final   int RANDOM_SECONDS=2;
    public static void main(String[] args) {
        int[] array=new int []{30,35,29,33,31,34,35,32,30,25};
        Condition condition=new Condition(30,5,"it-api@mail.foxconn.com");

        TemperatureSubject sub=new TemperatureSubject();
        //设置变量
        sub.setCondition(condition);

        NormalTemperatureObserver observer1=new NormalTemperatureObserver();
        AbnormalTemperatureObserver observer2=new AbnormalTemperatureObserver();
        //注册观察者
        sub.addObserver(observer1);
        sub.addObserver(observer2);

        for(int i=0;i
            int tempNum=array[i];
            sub.setRandomTemperature(tempNum);
            try {
                //休眠两秒后继续观测变化的温度数据
                TimeUnit.SECONDS.sleep(RANDOM_SECONDS);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

测试结果如下

当前温度为30
当前温度为35
当前温度为29
当前温度为29
当前温度为33
当前温度为31
当前温度为34
当前温度为35
当前温度为32
发送邮件it-api@mail.foxconn.com
当前温度为30
当前温度为25
当前温度为25