28.Java 实现线程间定制化通信

一、线程间定制化通信概述

• 让线程进行一定的顺序操作

二、实现线程间定制化通信

1、需求

• 启动三个线程，线程 AA 执行 5 次打印，线程 BB 执行 10 次打印，线程 CC 执行 15 次打印，一共进行 3 轮

2、思路

• 每个线程设置一个标志位（flag），线程的标志位对应则执行操作，并修改为下一个线程的标志位，通知下一个线程

3、具体实现

（1）资源类

package com.my.customizedcommunicate;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ShareRecourse {

    // 标志位
    private int flag;

    // 创建可重入锁
    private Lock lock;

    // 创建三个 Condition 对象
    private Condition c1;
    private Condition c2;
    private Condition c3;

    public ShareRecourse() {
        flag = 1;
        lock = new ReentrantLock();
        c1 = lock.newCondition();
        c2 = lock.newCondition();
        c3 = lock.newCondition();
    }

    // 每轮打印 5 次，参数为打印轮数
    public void print5(int loop) {
        lock.lock();
        try {
            while (flag != 1) {
                c1.await();
            }
            for (int i = 1; i <= 10; i++) {
                System.out.println(Thread.currentThread().getName() + "  打印次数：" + i + "  轮数：" + loop);
            }

            // 修改标志位，并通知下一个线程
            flag = 2;
            c2.signal();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    // 每轮打印 10 次，参数为打印轮数
    public void print10(int loop) {
        lock.lock();
        try {
            while (flag != 2) {
                c2.await();
            }
            for (int i = 1; i <= 10; i++) {
                System.out.println(Thread.currentThread().getName() + "  打印次数：" + i + "  轮数：" + loop);
            }

            // 修改标志位，并通知下一个线程
            flag = 3;
            c3.signal();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    // 每轮打印 15 次，参数为打印轮数
    public void print15(int loop) {
        lock.lock();
        try {
            while (flag != 3) {
                c3.await();
            }
            for (int i = 1; i <= 10; i++) {
                System.out.println(Thread.currentThread().getName() + "  打印次数：" + i + "  轮数：" + loop);
            }

            // 修改标志位，并通知下一个线程
            flag = 1;
            c1.signal();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}

（2）多线程测试

package com.my.customizedcommunicate;

public class ShareRecourseTest {
    public static void main(String[] args) {
        ShareRecourse shareRecourse = new ShareRecourse();

        Thread thread1 = new Thread(() -> {
            for (int i = 1; i <= 3; i++) {
                shareRecourse.print5(i);
            }
        }, "AA");
        Thread thread2 = new Thread(() -> {
            for (int i = 1; i <= 3; i++) {
                shareRecourse.print10(i);
            }
        }, "BB");
        Thread thread3 = new Thread(() -> {
            for (int i = 1; i <= 3; i++) {
                shareRecourse.print15(i);
            }
        }, "CC");

        thread1.start();
        thread2.start();
        thread3.start();
    }
}