DelayQueue应用场景,多考生考试
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该场景来自于:http://www.cnblogs.com/sunzhenchao/p/3515085.html。
模拟一个考试的日子,考试时间为120分钟,30分钟后才可交卷,当时间到了,或学生都交完卷了考试结束。
这个场景中几个点需要注意:
- 考试时间为120分钟,30分钟后才可交卷,初始化考生完成试卷时间最小应为30分钟
- 对于能够在120分钟内交卷的考生,如何实现这些考生交卷
- 对于120分钟内没有完成考试的考生,在120分钟考试时间到后需要让他们强制交卷
- 在所有的考生都交完卷后,需要将控制线程关闭
抽象出两个类,学生类和老师类,用DelayQueue存储考生(Student类)。每一个考生都有自己的名字和完成试卷的时间
Teacher线程对DelayQueue进行监控,收取完成试卷小于120分钟的学生的试卷。当考试时间120分钟到时,teacher线程宣布考试结束,强制DelayQueue中还存在的考生交卷。
package zhongqiu.common.base.thread; import java.util.Iterator; import java.util.Random; import java.util.concurrent.DelayQueue; import java.util.concurrent.Delayed; import java.util.concurrent.TimeUnit; public class DelayQueueDemoOne { public static void main(String[] args) throws InterruptedException { // TODO Auto-generated method stub int studentNumber = 20; DelayQueue<Student> students = new DelayQueue<Student>(); Random random = new Random(); for (int i = 0; i < studentNumber; i++) { students.put(new Student("student" + (i + 1), 30 + random.nextInt(120))); } students.put(new Student("student",120)); Thread teacherThread = new Thread(new Teacher(students)); teacherThread.start(); } } class Student implements Runnable, Delayed { private String name; public long workTime; private long submitTime; private boolean isForce = false; public Student() { } public Student(String name, long workTime) { this.name = name; this.workTime = workTime; this.submitTime = TimeUnit.NANOSECONDS.convert(workTime, TimeUnit.NANOSECONDS) + System.nanoTime();// 纳秒级别 } @Override public int compareTo(Delayed o) { // TODO Auto-generated method stub if (o == null || !(o instanceof Student)) return 1; if (o == this) return 0; Student s = (Student) o; if (this.workTime > s.workTime) { return 1; } else if (this.workTime == s.workTime) { return 0; } else { return -1; } } @Override public long getDelay(TimeUnit unit) { // TODO Auto-generated method stub return unit.convert(submitTime - System.nanoTime(), TimeUnit.NANOSECONDS); } @Override public void run() { // TODO Auto-generated method stub if (isForce) { System.out.println(name + " 交卷,实际用时 120分钟"); } else { System.out.println(name + " 交卷," + "实际用时 " + workTime + " 分钟"); } } public boolean isForce() { return isForce; } public void setForce(boolean isForce) { this.isForce = isForce; } } class Teacher implements Runnable { private int counter = 20; private DelayQueue<Student> students; public Teacher(DelayQueue<Student> students) { this.students = students; } @Override public void run() { // TODO Auto-generated method stub try { System.out.println(" test start"); while (counter > 0) { Student student = students.poll(); if (student.workTime<120) { student.run(); if (counter > 0) { counter--; } } else { System.out.println(" 考试时间到,全部交卷!"); Student tmpStudent; for (Iterator<Student> iterator2 = students.iterator(); iterator2.hasNext();) { tmpStudent = iterator2.next(); tmpStudent.setForce(true); tmpStudent.run(); if (counter > 0) { counter--; } } } } } catch (Exception e) { // TODO: handle exception e.printStackTrace(); } } }
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