DelayQueue用例

DelayQueue是一个延迟队列，插入队列的数据只有达到设置的延迟时间时才能被取出，否则线程会被阻塞。插入队列的对象必须实现Delayed接口，实现comapreTo方法和getDelay方法，其中getDelay方法用于设置对象延迟多少秒取出，compareTo用于对被延迟取出的数据进行排序，所以compareTo方法中一般调用对象的getDelay方法，根据对象的延迟时间进行排序。

首先是定义实现Delayed接口的类：

import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;
/**
 * 实现Delayed接口，用于插入延迟阻塞队列
 * @author SN
 *
 */
public class Worker implements Delayed{
	private String name;
	
	private String workNo;
	
	private long startTime;
	
	private long endTime;
	
	public static final TimeUnit TIME_UNIT=TimeUnit.SECONDS;
	
	public Worker(String name,String workNo,long startTime,long endTime){
		this.name=name;
		this.workNo=workNo;
		this.startTime=startTime;
		this.endTime=endTime;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getWorkNo() {
		return workNo;
	}

	public void setWorkNo(String workNo) {
		this.workNo = workNo;
	}

	public long getStartTime() {
		return startTime;
	}

	public void setStartTime(long startTime) {
		this.startTime = startTime;
	}

	public long getEndTime() {
		return endTime;
	}

	public void setEndTime(long endTime) {
		this.endTime = endTime;
	}

	//排序方法，用于将插入队列的对象按延迟时间进行排序
	@Override
	public int compareTo(Delayed delayed) {
		Worker worker=(Worker) delayed;
		return (this.getDelay(TIME_UNIT)-worker.getDelay(TIME_UNIT))>0?1:0;
	}

	//延迟时间，用于确定取出队列中数据的时间
	@Override
	public long getDelay(TimeUnit unit) {
		return endTime-System.currentTimeMillis();
	}
	
}

然后是测试向DelayQueue插入数据和取出数据：

import java.sql.Date;
import java.text.SimpleDateFormat;
import java.util.concurrent.DelayQueue;

/**
 * 向延迟队列中插入数据，并在到达延迟时间时从队列中取出数据，否则就阻塞当前线程
 * @author SN
 *
 */
public class DelayQueueExp implements Runnable{
	private DelayQueue<Worker> queue=new DelayQueue<>();
	public boolean working=true;
	public static final SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	//向延迟队列中插入数据，并设置延迟取出的时间
	public void startWork(String name,String workNo,int grade){
		long time=System.currentTimeMillis();
		Date date=new Date(time);
		Worker worker=new Worker(name, workNo, System.currentTimeMillis(), grade*10000+time);
		System.out.println("员工"+worker.getName()+",工号"+worker.getWorkNo()+"于"+sdf.format(date)+"打卡上班...");
		this.queue.add(worker);
	}
	
	public void endWork(Worker worker){
		Date date=new Date(worker.getEndTime());
		System.out.println("员工"+worker.getName()+",工号"+worker.getWorkNo()+"于"+sdf.format(date)+"打卡下班...");
	}
	
	@Override
	public void run() {
		while (working) {
			try {
				//启动线程后，从延迟队列中取出数据，如果没有满足延迟时间条件的数据可以取出就阻塞住线程
				Worker worker=queue.take();
				endWork(worker);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}

	public static void main(String[] args) {
		System.out.println("员工开始打卡上班...");
		DelayQueueExp company=new DelayQueueExp();
		Thread work=new Thread(company);
		work.start();
		//向延迟队列中插入数据
		company.startWork("zhangsan", "1001", 1);
		company.startWork("lisi", "1002", 3);
		company.startWork("wanger", "1003", 5);
	}
}

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