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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);
}
}