Current并发包(四) - lock

package com.wiscom.lock;
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public class LockDemo {
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    static int i = 0;
    public static void main(String[] args) throws InterruptedException {
        // true 为公平策略 false为非公平策略
        Lock l = new ReentrantLock(true);
        
        new Thread(new Add(l)).start();
        new Thread(new Add(l)).start();
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        Thread.sleep(2000);
        System.out.println(i);
    }
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}
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class Add implements Runnable {
    private Lock l;
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    public Add(Lock l) {
        this.l = l;
    }
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    @Override
    public void run() {
        // 加锁
        l.lock();
        for (int i = 0; i < 10000; i++) {
            LockDemo.i++;
        }
        // 解锁
        l.unlock();
    }
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}
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package com.wiscom.lock;
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public class CountDownLatchDemo {
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    public static void main(String[] args) throws InterruptedException {
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        CountDownLatch cdl = new CountDownLatch(6);
        new Thread(new Teacher(cdl)).start();
        new Thread(new Student(cdl)).start();
        new Thread(new Student(cdl)).start();
        new Thread(new Student(cdl)).start();
        new Thread(new Student(cdl)).start();
        new Thread(new Student(cdl)).start();
        // 在计数归零之前，需要让主函数所在线程先陷入阻塞
        // 当计数归零之后，自动的放开阻塞
        cdl.await();
        System.out.println("开始考试~~~");
    }
}
class Teacher implements Runnable {
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    private CountDownLatch cdl;
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    public Teacher(CountDownLatch cdl) {
        this.cdl = cdl;
    }
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    @Override
    public void run() {
        try {
            Thread.sleep((long) (Math.random() * 10000));
            System.out.println("考官到达考场~~~");
            // 减少1个计数
            cdl.countDown();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
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}
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class Student implements Runnable {
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    private CountDownLatch cdl;
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    public Student(CountDownLatch cdl) {
        this.cdl = cdl;
    }
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    @Override
    public void run() {
        try {
            Thread.sleep((long) (Math.random() * 10000));
            System.out.println("考生到达考场~~~");
            cdl.countDown();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
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}