关于java:并发队列PriorityBlockingQueue和DelayQueue案例使用

PriorityBlockingQueue 应用

import java.util.concurrent.PriorityBlockingQueue;

/**
 * @author：jiaolian
 * @date：Created in 2021-02-03 15:44
 * @description：priorityBlockingQueue 优先级队列测试
 * @modified By：* 公众号: 叫练
 */
public class PriorityBlockingQueueTest {public static void main(String[] args) {m2();
    }

    public static void m2() {PriorityBlockingQueue<Student> priorityBlockingQueue = new PriorityBlockingQueue<>();
        priorityBlockingQueue.add(new Student("叫练 1",22));
        priorityBlockingQueue.add(new Student("叫练 2",21));
        priorityBlockingQueue.add(new Student("叫练 3",23));
        while (!priorityBlockingQueue.isEmpty()) {
            Student student = null;
            try {student = priorityBlockingQueue.take();
            } catch (InterruptedException e) {e.printStackTrace();
            }
            System.out.println(student);
        }
    }

    private static class Student implements Comparable<Student> {
        private String name;
        private int age;

        public Student(String name, int age) {
            this.name = name;
            this.age = age;
        }

        public String getName() {return name;}

        public int getAge() {return age;}

        @Override
        public String toString() {
            return "Student{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }

        @Override
        public int compareTo(Student o) {
            // 从大到小排队
            return this.age - o.getAge();}
    }
}

如上代码：PriorityBlockingQueue是 优先级队列 ，PriorityBlockingQueue 队列的元素须要实现 Comparable 接口，实现队列的排序，上述代码中定义了 Student 类实现 Comparable 接口，Student 的 compareTo 接口依照 age 属性从小到大排队，输入后果如下图所示。PriorityBlockingQueue 底层是二叉均衡树的数组构造实现出队和入队。

DelayQueue 应用

import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;

/**
 * @author：jiaolian
 * @date：Created in 2021-02-03 16:28
 * @description：提早队列测试
 * @modified By：* 公众号: 叫练
 */
public class DelayQueueTest {public static void main(String[] args) throws InterruptedException {DelayQueue<Student> delayQueue = new DelayQueue<Student>();
        delayQueue.add(new Student("叫练 1",5));
        delayQueue.add(new Student("叫练 2",3));
        delayQueue.add(new Student("叫练 3",6));
        while (!delayQueue.isEmpty()) {System.out.println(delayQueue.take());
        }
    }


    private static class Student implements Delayed {
        private String name;
        // 触发工夫 / 秒
        private long time;

        public String getName() {return name;}


        public long getTime() {return time;}

        public Student(String name,  long time) {
            this.name = name;
            this.time = time*1000+System.currentTimeMillis();}

        @Override
        public long getDelay(TimeUnit unit) {
            // 延迟时间小于 0 就出队列
            long aa = time - System.currentTimeMillis();
            return aa;
        }

        @Override
        public int compareTo(Delayed o) {
            // 工夫排序, 从小到大排列
            Student student = (Student) o;
            return (int)(this.time - student.getTime());
        }

        @Override
        public String toString() {
            return "Student{" +
                    "name='" + name + '\'' +
                    ", time=" + time +
                    '}';
        }
    }
}

如上代码：DelayQueue是延时队列，只有到指定工夫的队列才能够出队列，底层应用优先级队列，下面代码定义 Student 类须要实现 Delayed 接口同时须要实现 getDelay 办法和 compareTo 办法，getDelay 办法用于计算出队列工夫，一旦小于 0 就会出队列；compareTo 办法用于按触发工夫从小到大排序。执行程序后，学生“叫练 2”3 秒后出队列；学生“叫练 1”5 秒后出队列；学生“叫练 3”6 秒后出队列。执行后果如下图所示。

总结

明天咱们的内容比较简单。喜爱的请点赞和评论哦！点关注，不迷路，我是叫练【公众号】，边叫边练。期待咱们下次再见！