多线程案例

一、生产者消费者案例

1、使用synchronized关键字实现

public class TestProductorAndConsumer {
        public static void main(String[] args) {
            Clerk clerk = new Clerk();
            Productor pro = new Productor(clerk);
            Consumer cus = new Consumer(clerk);
        
            new Thread(pro, "生产者 A").start();
            new Thread(cus, "消费者 B").start();
            new Thread(pro, "生产者 C").start();
            new Thread(cus, "消费者 D").start();
    }    
}
//店员
class Clerk{
    private int product = 0;
    //进货
    public synchronized void get(){    //循环次数：0
        while(product >= 1){    
            System.out.println("产品已满！");
            try {
                this.wait();    //为了避免虚假唤醒问题，wait应该总是使用在循环中
            } catch (InterruptedException e) {
            }    
        }
        System.out.println(Thread.currentThread().getName() + " : " + ++product);
        this.notifyAll();
    }
    //卖货
    public synchronized void sale(){    //product = 0; 循环次数：0
        while(product <= 0){
            System.out.println("缺货！");
            try {
                this.wait();
            } catch (InterruptedException e) {
            }
        }
        System.out.println(Thread.currentThread().getName() + " : " + --product);
        this.notifyAll();
    }
}
//生产者
class Productor implements Runnable{
    private Clerk clerk;
    public Productor(Clerk clerk) {
        this.clerk = clerk;
    }
    public void run() {
        for (int i = 0; i < 20; i++) {
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
            }
            clerk.get();
        }
    }
}
//消费者
class Consumer implements Runnable{
    private Clerk clerk;
    public Consumer(Clerk clerk) {
        this.clerk = clerk;
    }
    public void run() {
        for (int i = 0; i < 20; i++) {
            clerk.sale();
        }
    }
}

2、使用Lock同步锁和Condition类实现

public class TestProductorAndConsumerForLock {
    public static void main(String[] args) {
        Clerk clerk = new Clerk();
        Productor pro = new Productor(clerk);
        Consumer con = new Consumer(clerk);

        new Thread(pro, "生产者 A").start();
        new Thread(con, "消费者 B").start();
//        new Thread(pro, "生产者 C").start();
//        new Thread(con, "消费者 D").start();
    }
}
class Clerk {
    private int product = 0;
    private Lock lock = new ReentrantLock();
    private Condition condition = lock.newCondition();
    // 进货
    public void get() {
        lock.lock();
        try {
            if (product >= 1) { // 为了避免虚假唤醒，应该总是使用在循环中。
                System.out.println("产品已满！");
                try {
                    condition.await();
                } catch (InterruptedException e) {
                }
            }
            System.out.println(Thread.currentThread().getName() + " : "+ ++product);
            condition.signalAll();
        } finally {
            lock.unlock();
        }
    }
    // 卖货
    public void sale() {
        lock.lock();
        try {
            if (product <= 0) {
                System.out.println("缺货！");
                try {
                    condition.await();
                } catch (InterruptedException e) {
                }
            }
            System.out.println(Thread.currentThread().getName() + " : "+ --product);
            condition.signalAll();
        } finally {
            lock.unlock();
        }
    }
}

// 生产者
class Productor implements Runnable {
    private Clerk clerk;
    public Productor(Clerk clerk) {
        this.clerk = clerk;
    }
    public void run() {
        for (int i = 0; i < 20; i++) {
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            clerk.get();
        }
    }
}

// 消费者
class Consumer implements Runnable {
    private Clerk clerk;
    public Consumer(Clerk clerk) {
        this.clerk = clerk;
    }
    public void run() {
        for (int i = 0; i < 20; i++) {
            clerk.sale();
        }
    }
}

 3、使用阻塞队列实现

class Producer implements Runnable{
    private final BlockingQueue sharedQueue;

    public Producer(BlockingQueue sharedQueue){
        thsi.sharedQueue = sharedQueue;
    }

    public void run(){
        for(int i=0;i<10;i++){
            try{
                System.out.println("Produced: "+i);
                sharedQueue.put(i);
            }catch(InterruptedExcepion ex){
                System.out.println(ex)
            }
        }
    }
}

class Consumer implements Runnable{
    private final BlockingQueue sharedQueue;

    public Consumer (BlockingQueue sharedQueue){
        this.sharedQueue = sharedQueue;
    }

    public void run(){
        while(true){
            try{
                int i = (Integer)sharedQueue.take();
                System.out.println("Consumed: " +i);
            }catch(InterruptedException ex){
                System.out.println(ex);
            }
        }
    }
}

public class ProducerConsumerPattern{
    public static void main(String[] args){
        BlockingQueue sharedQueue = new LinkedBlockingQueue();

        Thread proThread = new Thread (new Producer(sharedQueue));
        Thread consThread = new Thread (new Consumer(sharedQueue));

        proThread.start();
        consThread.start();
    }
}

二、线程按序交替

　　编写一个程序，开启3个线程，这三个线程的ID分别为A、B、C，每个线程将自己的ID在屏幕上打印10遍，要求输出的结果必须按顺序显示。如：ABCABC......依次递归。

public class TestABCAlternate {
    public static void main(String[] args) {
        AlternateDemo ad = new AlternateDemo();
        new Thread(new Runnable() {
            public void run() {
                for (int i = 1; i <= 10; i++) {
                    ad.loopA(i);
                }    
            }
        }, "A").start();
        new Thread(new Runnable() {
            public void run() {    
                for (int i = 1; i <= 10; i++) {
                    ad.loopB(i);
                }    
            }
        }, "B").start();
        new Thread(new Runnable() {
            public void run() {
                for (int i = 1; i <= 10; i++) {
                    ad.loopC(i);
                    System.out.println("-----------------------------------");
                }    
            }
        }, "C").start();
    }
}

class AlternateDemo{
    private int number = 1; //当前正在执行线程的标记
    private Lock lock = new ReentrantLock();
    private Condition condition1 = lock.newCondition();
    private Condition condition2 = lock.newCondition();
    private Condition condition3 = lock.newCondition();
    
    public void loopA(int totalLoop){    //totalLoop : 循环第几轮
        lock.lock();
        try {
            if(number != 1){    //1. 判断
                condition1.await();
            }
            //2. 打印
            for (int i = 1; i <= 1; i++) {
                System.out.println(Thread.currentThread().getName() + "	" + i + "	" + totalLoop);
            }
            //3. 唤醒
            number = 2;
            condition2.signal();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
    public void loopB(int totalLoop){
        lock.lock();
        try {
            if(number != 2){    //1. 判断
                condition2.await();
            }
            //2. 打印
            for (int i = 1; i <= 1; i++) {
                System.out.println(Thread.currentThread().getName() + "	" + i + "	" + totalLoop);
            }
            //3. 唤醒
            number = 3;
            condition3.signal();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
    public void loopC(int totalLoop){
        lock.lock();
        try {
            if(number != 3){    //1. 判断
                condition3.await();
            }    
            //2. 打印
            for (int i = 1; i <= 1; i++) {
                System.out.println(Thread.currentThread().getName() + "	" + i + "	" + totalLoop);
            }
            //3. 唤醒
            number = 1;
            condition1.signal();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }
}