delayqueue

DelayedQueue是一个用来延时处理的队列。可以为队列中的元素添加一个过期的时间，

队列中的元素 要实现 delay接口中的两个方法

​存入队列：add offer put

从队列中获取：peek poll take​

peek：获取队列的head对象，但不是从队列中移除。如果队列空，就返回空

poll ：​获取并移出队列head对象。如果head没有超时，返回空

poll w/ timeout参数 ： ​获取并移出队列head对象。如果没有超时head对象，会wait当前线程知道有超时对象，或者按照超时参数设定，返回空

take ： ​获取并移出队列head对象。如果没有超时head对象，会wait当前线程知道有对象满足超时条件

​DelayedQueue实现保证了最快过期的对象排在head位置，也就是说它会在每次peek时候返回最快超时的对象。

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) throws InterruptedException {
        DelayQueue<Person> delayQueue =  new DelayQueue<>();
        delayQueue.clear();
        Calendar calendar = Calendar.getInstance();
        for (int i=1;i<11;i++){
            calendar.add(Calendar.SECOND,i*10);
            Person m = new Person(i+" is id",i+" is name",System.currentTimeMillis()+i*1000,calendar.getTime());
            delayQueue.add(m);
        }
        Iterator<Person> iterator = delayQueue.iterator();
        while(iterator.hasNext()){
            Person p=iterator.next();
            System.out.println(p);
        }
        while(!delayQueue.isEmpty()){
            Person message = delayQueue.take();//阻塞方法
            System.out.println(message);
        }
 
    }
}

class Person implements Delayed{
    private String id;
    private String name;
    private long insertTime;
    private Date outTime;
    
    public Person(String id, String name,long insertTime,Date outTime) {
        super();
        this.id = id;
        this.name = name;
        this.insertTime = insertTime;
        this.outTime = outTime;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public long getInsertTime() {
        return insertTime;
    }
    public void setInsertTime(long insertTime) {
        this.insertTime = insertTime;
    }
    public Date getOutTime() {
        return outTime;
    }
    public void setOutTime(Date outTime) {
        this.outTime = outTime;
    }
    @Override
    public String toString() {
        return "Person [id=" + id + ", name=" + name + ", outTime=" + new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(outTime) + "]";
    }
    @Override
    public int compareTo(Delayed o) {
        Person person = (Person) o;
        
        if(this.insertTime > person.insertTime){
            return 1;
        }else if(this.insertTime == person.insertTime){
            return 0;
        }else{
            return -1;
        }
    }
    @Override
    public long getDelay(TimeUnit unit) {
        return this.outTime.getTime()-System.currentTimeMillis();
    }
    
}