java线程之间通信，多种方式实现生产者消费者模式

Posted 2020-12-17 lkjhgfdsa123

java多线程之间的通信，及使用多种方式实现生产者消费者模式

实现需求：两个线程交替打印1,0，打印10轮

 

java多线程口诀：

1. 高内聚，低耦合
2. 线程操作资源类
3. 判断干活通知
4. 防止虚假唤醒

 

方式一：使用synchronized和Object的wait和notifyAll方法

 

wait:使当前线程阻塞

notify,notifyAll唤醒当前线程

/**
 * 两个线程交替打印1，0 打印10轮
 * 
 * @author Administrator
 * @version 1.0 2020年7月12日
 * @see ProdConsumerDemo1
 * @since 1.0
 * 
 */
class ShareData1 {

    public int number = 0;

    public synchronized void increment() throws Exception {
        while (number != 0) {
            this.wait();
        }
        number++;
        System.out.println(Thread.currentThread().getName() + " " + number);
        this.notifyAll();
    }

    public synchronized void decrement() throws InterruptedException {
        while (number != 1) {
            this.wait();
        }
        number--;
        System.out.println(Thread.currentThread().getName() + " " + number);
        this.notifyAll();
    }
}

public class ProdConsumerDemo1 {

    public static void main(String[] args) {
        ShareData1 shareData = new ShareData1();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    shareData.increment();
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }, "A").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    shareData.decrement();
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }, "B").start();
    }
}

　　

输出结果

A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0

方式二：使用jdk1.8的Lock和Condition

class ShareData2 {

    private int number = 0;

    private Lock lock = new ReentrantLock();

    private Condition condition = lock.newCondition();

    public void increment() throws Exception {
        lock.lock();
        try {
            while (number != 0) {
                condition.await();
            }
            number++;
            System.out.println(Thread.currentThread().getName() + " " + number);
            condition.signalAll();
        } finally {
            lock.unlock();
        }
    }

    public void decrement() throws InterruptedException {
        lock.lock();
        try {
            while (number != 1) {
                condition.await();
            }
            number--;
            System.out.println(Thread.currentThread().getName() + " " + number);
            condition.signalAll();
        } finally {
            // TODO: handle finally clause
            lock.unlock();
        }
    }
}

public class ProdConsumerDemo2 {

    public static void main(String[] args) {
        ShareData2 shareData = new ShareData2();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    shareData.increment();
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }, "A").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    shareData.decrement();
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }, "B").start();
    }
}

　　

输出结果

A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0
A 1
B 0

主要是熟悉Lock和Condition的使用

 

Lock和Condition相比于synchronized，能够精确唤醒

需求：三个线程A,B,C顺序打印，A打印5次，B打印10次，C打印15次，10轮

class ShareData3 {

    private int number = 1;

    private Lock lock = new ReentrantLock();

    private Condition c1 = lock.newCondition();

    private Condition c2 = lock.newCondition();

    private Condition c3 = lock.newCondition();

    public void print5() throws Exception {
        lock.lock();
        try {
            while (number != 1) {
                c1.await();
            }
            number = 2;
            for (int i = 0; i < 5; i++) {
                System.out.println(Thread.currentThread().getName() + " " + i);
            }
            c2.signalAll();
        } finally {
            // TODO: handle finally clause
            lock.unlock();
        }
    }

    public void print10() throws InterruptedException {
        lock.lock();
        try {
            while (number != 2) {
                c2.await();
            }
            number=3;
            for (int i = 0; i < 10; i++) {
                System.out.println(Thread.currentThread().getName() + " " + i);
            }
            c3.signalAll();
        } finally {
            // TODO: handle finally clause
            lock.unlock();
        }
    }

    public void print15() throws InterruptedException {
        lock.lock();
        try {
            while (number != 3) {
                c3.await();
            }
            number = 1;
            for (int i = 0; i < 15; i++) {
                System.out.println(Thread.currentThread().getName() + " " + i);
            }
            c1.signalAll();
        } finally {
            // TODO: handle finally clause
            lock.unlock();
        }
    }
}

public class ProdConsumerDemo3 {

    public static void main(String[] args) {
        ShareData3 shareData3 = new ShareData3();
        new Thread(() -> {
            try {
                for (int i = 0; i < 10; i++) {
                    shareData3.print5();
                }
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }, "A").start();
        new Thread(() -> {
            try {
                for (int i = 0; i < 10; i++) {
                    shareData3.print10();
                }
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }, "B").start();
        new Thread(() -> {
            try {
                for (int i = 0; i < 10; i++) {
                    shareData3.print15();
                }
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }, "C").start();
    }
}