其中读者写者和贪睡的理发师使用的Semaphore类；生产者消费者使用的是管程。

读者写者

class Semaphore
{int value;public Semaphore(int v){this.value = v;}public synchronized void p(){value -= 1;if (value < 0){try{wait();} catch (InterruptedException e){e.printStackTrace();}}}public synchronized void v(){value += 1;if (value <= 0){this.notify();}}
}class Reader implements Runnable
{int count;Semaphore rmutex;Semaphore wmutex;public Reader(int c, Semaphore r, Semaphore w){this.count = c;this.rmutex = r;this.wmutex = w;}public void run(){while (true){rmutex.p();if (count == 0){wmutex.p();System.out.println("****************************reader has got lock no writer is allowed*************************");System.out.println("ReaderReaderReaderReader Thread: " + Thread.currentThread().getName()+ " current count= " + count);}count++;rmutex.v();System.out.println("I AM Reader: " + Thread.currentThread().getName() + " count= " + count + " I am DOING SOME JOB!");try{Thread.sleep((long) (Math.random() * 1000));} catch (InterruptedException e){e.printStackTrace();}rmutex.p();count--;System.out.println("I AM Reader: " + Thread.currentThread().getName() + " count= " + count + " I am quiting work");if (count == 0){
//                System.out.println(
//                        "ReaderReaderReaderReader Thread: " + Thread.currentThread().getName() + "give up lock");wmutex.v();System.out.println("****************************readers all give up lock*************************");System.out.println();}rmutex.v();try{Thread.sleep((long) (Math.random() * 1000));} catch (InterruptedException e){e.printStackTrace();}}}
}class Writer implements Runnable
{Semaphore wmutex;public Writer(Semaphore w){this.wmutex = w;}public void run(){while (true){wmutex.p();System.out.println("====================writer has got lock no reader is allowed===================================");System.out.println("WriterWriterWriter Thread: " + Thread.currentThread().getName());System.out.println("begin writting data...");try{Thread.sleep((long) (Math.random() * 1000));} catch (InterruptedException e){e.printStackTrace();}System.out.println("finish writting data.");wmutex.v();System.out.println("=======================================writer give up lock==========================================");System.out.println();}}
}public class ReaderWriter
{public static void main(String[] args){int count = 0;Semaphore rmutex = new Semaphore(1);Semaphore wmutex = new Semaphore(1);Reader reader = new Reader(count, rmutex, wmutex);Writer writer = new Writer(wmutex);Thread r1 = new Thread(reader);Thread r2 = new Thread(reader);Thread w1 = new Thread(writer);Thread w2 = new Thread(writer);w1.start();r1.start();w2.start();try{Thread.sleep(1000);} catch (InterruptedException e){e.printStackTrace();}r2.start();}
}

贪睡的理发师

class Semaphore{int value;public Semaphore(int v) {this.value = v;}public synchronized void p() {value--;if(value < 0) {try {wait();}catch(InterruptedException e) {e.printStackTrace();}}}public synchronized void v() {value++;if(value <= 0) {notifyAll();}}
}class Customer implements Runnable{Semaphore mutex;Semaphore customer;Semaphore barber;int index;public Customer(int index, Semaphore mutex, Semaphore customer, Semaphore barber) {this.index = index;this.mutex = mutex;this.customer = customer;this.barber = barber;}public void run() {mutex.p();if(BC.count >= BC.MAX) {System.out.println("椅子已经坐满，顾客" + index + " 离开");mutex.v();}else {BC.count++;customer.v(); // 通知理发师等待理发人数加1mutex.v();barber.p();       // 抢夺理发师System.out.println("顾客" + index + " 开始理发");
//          System.out.println("顾客： " + Thread.currentThread().getName().toString() + " 正在理发");}}
}class Barbe implements Runnable{Semaphore mutex;Semaphore customer;Semaphore barber;public Barbe(Semaphore mutex, Semaphore customer, Semaphore barber) {this.mutex = mutex;this.customer = customer;this.barber = barber;}public void run() {while(true) {customer.p();mutex.p();BC.count--;barber.v();mutex.v();System.out.println(" 理发师理发");try {Thread.sleep((long)(Math.random() * 1000));}catch(InterruptedException e) {e.printStackTrace();}}}
}public class BC{static int count;static int MAX = 5;static Semaphore mutex = new Semaphore(1); static Semaphore barber = new Semaphore(1);static Semaphore customer = new Semaphore(0);public static void main(String[] args) {Barbe bar = new Barbe(mutex, customer, barber);Thread b1 = new Thread(bar);b1.start();int n = 10;for(int i=0;i<n;i++) {Customer cus = new Customer(i, mutex, customer, barber);Thread t = new Thread(cus);t.start();System.out.println("顾客: " + i + " 等待理发");try {Thread.sleep((long)(Math.random() * 2000));}catch(InterruptedException e) {e.printStackTrace();}}}}

监控器实现的是生产者消费者

什么是监控器？

监控器每次只能由一个线程访问；对共享变量的访问只能发生在监控器内定义的过程中。

import java.util.Vector;class CP{Vector pool;int product = 0; // 产品数量public static int EMPTY = 0;public static int FULL = 25;public CP() {pool = new Vector();}public synchronized void produce() {try {if(pool.size() == FULL)wait();product++;pool.addElement(new Integer(product));// 把产品放到产品池中System.out.println("Produce: " + product);if(pool.size() == EMPTY + 1)notify();}catch(InterruptedException e) {e.printStackTrace();}}public synchronized void consume() {try {if(pool.size() == EMPTY)wait();System.out.println("Consume: " + pool.firstElement().toString());pool.removeElementAt(0);if(pool.size() == FULL - 1)notify();}catch(InterruptedException e) {e.printStackTrace();}}
}class Producer extends Thread{CP cp;public Producer(CP cp) {super();this.cp = cp;}public void run() {while(true) {cp.produce();//模拟做其他工作try {Thread.sleep((long)(Math.random()* 1000));}catch(InterruptedException e) {e.printStackTrace();}}}
}class Consumer extends Thread{CP cp;public Consumer(CP cp) {super();this.cp = cp;}public void run() {while(true) {cp.consume();//模拟做其他事情try {Thread.sleep((long)(Math.random() * 1000));}catch(InterruptedException e) {e.printStackTrace();}}}
}public class ProducerConsumer{public static void main(String[] args) {CP cp = new CP();Producer producer = new Producer(cp);Consumer consumer = new Consumer(cp);producer.start();consumer.start();}
}

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java实现的PV操作经典例子：读者写者、贪睡的理发师、生产者消费者。

读者写者

贪睡的理发师

监控器实现的是生产者消费者

java实现的PV操作经典例子：读者写者、贪睡的理发师、生产者消费者。相关推荐

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