java线程间协作的另一种方式——await()、signal()、signalAll()

柔情只为你懂 2022-05-20 23:10 939阅读 0赞

本文主要参考：

《Think in java》

ExecutorService中有一ReentrantLock，可以使用这个锁，同时还有对应的这个await()方法。

使用这种方法的时候必须使用ExecutorService。

我们还是以先扫地，再拖地的这个为例。

首先创建调度器类：

package com.xueyou.demo.threadcooperateexecutorservice;
    
    import java.util.concurrent.locks.Condition;
    import java.util.concurrent.locks.Lock;
    import java.util.concurrent.locks.ReentrantLock;
    
    public class SweepAndMopDispacherNew {
        private Lock lock = new ReentrantLock();
        private Condition condition = lock.newCondition();
        private boolean isSweeping = false;
    
        public void sweeped() {
            lock.lock();
            try {
                isSweeping = true;
                condition.signalAll();
            } finally {
                lock.unlock();
            }
        }
    
        public synchronized void Mopped() {
            lock.lock();
            try {
                isSweeping = false;
                condition.signalAll();
            } finally {
                lock.unlock();
            }
        }
    
        public void waitForSweeped() throws InterruptedException {
            lock.lock();
            try {
                while (isSweeping == false) {
                    condition.await();
                }
            } finally {
                lock.unlock();
            }
        }
    
        public void waitForMopped() throws InterruptedException {
            lock.lock();
            try {
                while (isSweeping == true) {
                    condition.await();
                }
            } finally {
                lock.unlock();
            }
        }
    }

2、然后分别创建扫地和拖地线程。

package com.xueyou.demo.threadcooperateexecutorservice;
    
    import java.util.concurrent.TimeUnit;
    
    public class SweepRunner implements Runnable {
        private SweepAndMopDispacherNew dispacher;
    
        public SweepRunner(SweepAndMopDispacherNew dispacher) {
            this.dispacher = dispacher;
        }
    
        @Override
        public void run() {
            try {
                while (!Thread.interrupted()) {
                    System.out.println(Thread.currentThread().getName() + "扫地..");
                    TimeUnit.MILLISECONDS.sleep(800);
                    dispacher.sweeped();
                    dispacher.waitForMopped();
                }
            } catch (InterruptedException e) {
                System.out.println("exit by interrupted");
            } finally {
                System.out.println("mop exit;");
            }
        }
    }
    
    package com.xueyou.demo.threadcooperateexecutorservice;
    
    import java.util.concurrent.TimeUnit;
    
    public class MopRunner implements Runnable {
        private SweepAndMopDispacherNew dispacher;
    
        public MopRunner(SweepAndMopDispacherNew dispacher) {
            this.dispacher = dispacher;
        }
    
        @Override
        public void run() {
            try {
                while (!Thread.interrupted()) {
                    System.out.println(Thread.currentThread().getName() + "拖地..");
                    TimeUnit.MILLISECONDS.sleep(800);
                    dispacher.Mopped();
                    dispacher.waitForSweeped();
                }
            } catch (InterruptedException e) {
                System.out.println("exit by interrupted");
            } finally {
                System.out.println("Mop runner exit;");
            }
        }
    }

3、编写一个测试类进行测试

package com.xueyou.demo.threadcooperateexecutorservice;
    
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.TimeUnit;
    
    public class TestMain {
        public static void main(String[] args) {
            SweepAndMopDispacherNew dispacher = new SweepAndMopDispacherNew();
            ExecutorService executorService = Executors.newCachedThreadPool();
            executorService.submit(new SweepRunner(dispacher));
            executorService.submit(new MopRunner(dispacher));
            try {
                TimeUnit.SECONDS.sleep(5);
                executorService.shutdownNow();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

4、测试运行结果如下：

![70][]

[70]: /images/20220521/9d55827030524b289f84babd2a9852ec.png