2、生产者-消费者模式的三种实现方式
1、背景
生产者生产数据到缓冲区中,消费者从缓冲区中取数据。
如果缓冲区已经满了,则生产者线程阻塞;
如果缓冲区为空,那么消费者线程阻塞。
2、方式一:synchronized、wait和notify
1 package producerConsumer; 2 //wait 和 notify 3 public class ProducerConsumerWithWaitNofity { 4 public static void main(String[] args) { 5 Resource resource = new Resource(); 6 //生产者线程 7 ProducerThread p1 = new ProducerThread(resource); 8 ProducerThread p2 = new ProducerThread(resource); 9 ProducerThread p3 = new ProducerThread(resource); 10 //消费者线程 11 ConsumerThread c1 = new ConsumerThread(resource); 12 //ConsumerThread c2 = new ConsumerThread(resource); 13 //ConsumerThread c3 = new ConsumerThread(resource); 14 15 p1.start(); 16 p2.start(); 17 p3.start(); 18 c1.start(); 19 //c2.start(); 20 //c3.start(); 21 } 22 23 24 25 } 26 /** 27 * 公共资源类 28 * @author 29 * 30 */ 31 class Resource{//重要 32 //当前资源数量 33 private int num = 0; 34 //资源池中允许存放的资源数目 35 private int size = 10; 36 37 /** 38 * 从资源池中取走资源 39 */ 40 public synchronized void remove(){ 41 if(num > 0){ 42 num--; 43 System.out.println("消费者" + Thread.currentThread().getName() + 44 "消耗一件资源," + "当前线程池有" + num + "个"); 45 notifyAll();//通知生产者生产资源 46 }else{ 47 try { 48 //如果没有资源,则消费者进入等待状态 49 wait(); 50 System.out.println("消费者" + Thread.currentThread().getName() + "线程进入等待状态"); 51 } catch (InterruptedException e) { 52 e.printStackTrace(); 53 } 54 } 55 } 56 /** 57 * 向资源池中添加资源 58 */ 59 public synchronized void add(){ 60 if(num < size){ 61 num++; 62 System.out.println(Thread.currentThread().getName() + "生产一件资源,当前资源池有" 63 + num + "个"); 64 //通知等待的消费者 65 notifyAll(); 66 }else{ 67 //如果当前资源池中有10件资源 68 try{ 69 wait();//生产者进入等待状态,并释放锁 70 System.out.println(Thread.currentThread().getName()+"线程进入等待"); 71 }catch(InterruptedException e){ 72 e.printStackTrace(); 73 } 74 } 75 } 76 } 77 /** 78 * 消费者线程 79 */ 80 class ConsumerThread extends Thread{ 81 private Resource resource; 82 public ConsumerThread(Resource resource){ 83 this.resource = resource; 84 } 85 @Override 86 public void run() { 87 while(true){ 88 try { 89 Thread.sleep(1000); 90 } catch (InterruptedException e) { 91 e.printStackTrace(); 92 } 93 resource.remove(); 94 } 95 } 96 } 97 /** 98 * 生产者线程 99 */ 100 class ProducerThread extends Thread{ 101 private Resource resource; 102 public ProducerThread(Resource resource){ 103 this.resource = resource; 104 } 105 @Override 106 public void run() { 107 //不断地生产资源 108 while(true){ 109 try { 110 Thread.sleep(1000); 111 } catch (InterruptedException e) { 112 e.printStackTrace(); 113 } 114 resource.add(); 115 } 116 } 117 118 }
3、方式二:lock和condition的await、signalAll
1 package producerConsumer; 2 3 import java.util.concurrent.locks.Condition; 4 import java.util.concurrent.locks.Lock; 5 import java.util.concurrent.locks.ReentrantLock; 6 /** 7 * 使用Lock 和 Condition解决生产者消费者问题 8 * @author tangzhijing 9 * 10 */ 11 public class LockCondition { 12 public static void main(String[] args) { 13 Lock lock = new ReentrantLock(); 14 Condition producerCondition = lock.newCondition(); 15 Condition consumerCondition = lock.newCondition(); 16 Resource2 resource = new Resource2(lock,producerCondition,consumerCondition); 17 18 //生产者线程 19 ProducerThread2 producer1 = new ProducerThread2(resource); 20 21 //消费者线程 22 ConsumerThread2 consumer1 = new ConsumerThread2(resource); 23 ConsumerThread2 consumer2 = new ConsumerThread2(resource); 24 ConsumerThread2 consumer3 = new ConsumerThread2(resource); 25 26 producer1.start(); 27 consumer1.start(); 28 consumer2.start(); 29 consumer3.start(); 30 } 31 } 32 /** 33 * 消费者线程 34 */ 35 class ConsumerThread2 extends Thread{ 36 private Resource2 resource; 37 public ConsumerThread2(Resource2 resource){ 38 this.resource = resource; 39 //setName("消费者"); 40 } 41 public void run(){ 42 while(true){ 43 try { 44 Thread.sleep((long) (1000 * Math.random())); 45 } catch (InterruptedException e) { 46 e.printStackTrace(); 47 } 48 resource.remove(); 49 } 50 } 51 } 52 /** 53 * 生产者线程 54 * @author tangzhijing 55 * 56 */ 57 class ProducerThread2 extends Thread{ 58 private Resource2 resource; 59 public ProducerThread2(Resource2 resource){ 60 this.resource = resource; 61 setName("生产者"); 62 } 63 public void run(){ 64 while(true){ 65 try { 66 Thread.sleep((long) (1000 * Math.random())); 67 } catch (InterruptedException e) { 68 e.printStackTrace(); 69 } 70 resource.add(); 71 } 72 } 73 } 74 /** 75 * 公共资源类 76 * @author tangzhijing 77 * 78 */ 79 class Resource2{ 80 private int num = 0;//当前资源数量 81 private int size = 10;//资源池中允许存放的资源数目 82 private Lock lock; 83 private Condition producerCondition; 84 private Condition consumerCondition; 85 public Resource2(Lock lock, Condition producerCondition, Condition consumerCondition) { 86 this.lock = lock; 87 this.producerCondition = producerCondition; 88 this.consumerCondition = consumerCondition; 89 90 } 91 /** 92 * 向资源池中添加资源 93 */ 94 public void add(){ 95 lock.lock(); 96 try{ 97 if(num < size){ 98 num++; 99 System.out.println(Thread.currentThread().getName() + 100 "生产一件资源,当前资源池有" + num + "个"); 101 //唤醒等待的消费者 102 consumerCondition.signalAll(); 103 }else{ 104 //让生产者线程等待 105 try { 106 producerCondition.await(); 107 System.out.println(Thread.currentThread().getName() + "线程进入等待"); 108 } catch (InterruptedException e) { 109 e.printStackTrace(); 110 } 111 } 112 }finally{ 113 lock.unlock(); 114 } 115 } 116 /** 117 * 从资源池中取走资源 118 */ 119 public void remove(){ 120 lock.lock(); 121 try{ 122 if(num > 0){ 123 num--; 124 System.out.println("消费者" + Thread.currentThread().getName() 125 + "消耗一件资源," + "当前资源池有" + num + "个"); 126 producerCondition.signalAll();//唤醒等待的生产者 127 }else{ 128 try { 129 consumerCondition.await(); 130 System.out.println(Thread.currentThread().getName() + "线程进入等待"); 131 } catch (InterruptedException e) { 132 e.printStackTrace(); 133 }//让消费者等待 134 } 135 }finally{ 136 lock.unlock(); 137 } 138 } 139 140 }
4、方式三:BlockingQueue
1 package producerConsumer; 2 3 import java.util.concurrent.BlockingQueue; 4 import java.util.concurrent.LinkedBlockingQueue; 5 6 //使用阻塞队列BlockingQueue解决生产者消费者 7 public class BlockingQueueConsumerProducer { 8 public static void main(String[] args) { 9 Resource3 resource = new Resource3(); 10 //生产者线程 11 ProducerThread3 p = new ProducerThread3(resource); 12 //多个消费者 13 ConsumerThread3 c1 = new ConsumerThread3(resource); 14 ConsumerThread3 c2 = new ConsumerThread3(resource); 15 ConsumerThread3 c3 = new ConsumerThread3(resource); 16 17 p.start(); 18 c1.start(); 19 c2.start(); 20 c3.start(); 21 } 22 } 23 /** 24 * 消费者线程 25 * @author tangzhijing 26 * 27 */ 28 class ConsumerThread3 extends Thread { 29 private Resource3 resource3; 30 31 public ConsumerThread3(Resource3 resource) { 32 this.resource3 = resource; 33 //setName("消费者"); 34 } 35 36 public void run() { 37 while (true) { 38 try { 39 Thread.sleep((long) (1000 * Math.random())); 40 } catch (InterruptedException e) { 41 e.printStackTrace(); 42 } 43 resource3.remove(); 44 } 45 } 46 } 47 /** 48 * 生产者线程 49 * @author tangzhijing 50 * 51 */ 52 class ProducerThread3 extends Thread{ 53 private Resource3 resource3; 54 public ProducerThread3(Resource3 resource) { 55 this.resource3 = resource; 56 //setName("生产者"); 57 } 58 59 public void run() { 60 while (true) { 61 try { 62 Thread.sleep((long) (1000 * Math.random())); 63 } catch (InterruptedException e) { 64 e.printStackTrace(); 65 } 66 resource3.add(); 67 } 68 } 69 } 70 class Resource3{ 71 private BlockingQueue resourceQueue = new LinkedBlockingQueue(10); 72 /** 73 * 向资源池中添加资源 74 */ 75 public void add(){ 76 try { 77 resourceQueue.put(1); 78 System.out.println("生产者" + Thread.currentThread().getName() 79 + "生产一件资源," + "当前资源池有" + resourceQueue.size() + 80 "个资源"); 81 } catch (InterruptedException e) { 82 e.printStackTrace(); 83 } 84 } 85 /** 86 * 向资源池中移除资源 87 */ 88 public void remove(){ 89 try { 90 resourceQueue.take(); 91 System.out.println("消费者" + Thread.currentThread().getName() + 92 "消耗一件资源," + "当前资源池有" + resourceQueue.size() 93 + "个资源"); 94 } catch (InterruptedException e) { 95 e.printStackTrace(); 96 } 97 } 98 }