Java实现生产者和消费者的5种方式
转自https://blog.csdn.net/wowwilliam0/article/details/80875673
面试的时候会让手撕，生产者消费者模式，生产者消费者模式，涉及线程同步与通信的问题。
实现方式有
wait/notify|notifyAll
ReetrantLock锁
阻塞队列
信号量Semaphore
管道输入输出流
wait()和notify()方法的实现
package cn.yu.test;
public class Main {
private static Integer count = 0;
private static final Integer full = 10;
private static Object obj = new Object();
public static void main(String [] args){
}
class Producer implements Runnable{
@Override
public void run() {
for(int i = 0;i<10;i++) {
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized(obj) {
while(count == full) {
try {
obj.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
count ++;
obj.notifyAll();
}
}
}
}
class Consumer implements Runnable{
@Override
public void run() {
for(int i = 0;i<10;i++) {
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized(obj) {
while(count == 0) {
try {
obj.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
count --;
obj.notifyAll();
}
}
}
}
可重入锁ReentrantLock实现
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* 生产者和消费者，ReentrantLock的实现
*
* @author ZGJ
* @date 2017年6月22日
*/
public class Test2 {
private static Integer count = 0;
private static final Integer FULL = 10;
//创建一个锁对象
private Lock lock = new ReentrantLock();
//创建两个条件变量，一个为缓冲区非满，一个为缓冲区非空
private final Condition notFull = lock.newCondition();
private final Condition notEmpty = lock.newCondition();
public static void main(String[] args) {
Test2 test2 = new Test2();
new Thread(test2.new Producer()).start();
new Thread(test2.new Consumer()).start();
new Thread(test2.new Producer()).start();
new Thread(test2.new Consumer()).start();
new Thread(test2.new Producer()).start();
new Thread(test2.new Consumer()).start();
new Thread(test2.new Producer()).start();
new Thread(test2.new Consumer()).start();
}
class Producer implements Runnable {
@Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep(3000);
} catch (Exception e) {
e.printStackTrace();
}
//获取锁
lock.lock();
try {
while (count == FULL) {
try {
notFull.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
count++;
System.out.println(Thread.currentThread().getName()
+ "生产者生产，目前总共有" + count);
//唤醒消费者
notEmpty.signal();
} finally {
//释放锁
lock.unlock();
}
}
}
}
class Consumer implements Runnable {
@Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep(3000);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
lock.lock();
try {
while (count == 0) {
try {
notEmpty.await();
} catch (Exception e) {
e.printStackTrace();
}
}
count--;
System.out.println(Thread.currentThread().getName()
+ "消费者消费，目前总共有" + count);
notFull.signal();
} finally {
lock.unlock();
}
}
}
}
}
阻塞队列BlockingQueue的实现
public class Main {
private static Integer count = 0;
//创建一个阻塞队列
final BlockingQueue bolckingQueue = new ArrayBlockingQueue<>(10);
public static void main(String []args) {
}
class Producer implements Runnable{
@Override
public void run() {
for(int i = 0;i<10;i++) {
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
try {
bolckingQueue.put(1);
count ++;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
class Consumer implements Runnable{
@Override
public void run() {
for(int i = 0;i<10;i++) {
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
try {
bolckingQueue.take();
count --;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
信号量Semaphore的实现
import java.util.concurrent.Semaphore;
/**
* 使用semaphore信号量实现
* @author ZGJ
* @date 2017年6月29日
*/
public class Test4 {
private static Integer count = 0;
//创建三个信号量
final Semaphore notFull = new Semaphore(10);
final Semaphore notEmpty = new Semaphore(0);
final Semaphore mutex = new Semaphore(1);
public static void main(String[] args) {
Test4 test4 = new Test4();
new Thread(test4.new Producer()).start();
new Thread(test4.new Consumer()).start();
new Thread(test4.new Producer()).start();
new Thread(test4.new Consumer()).start();
new Thread(test4.new Producer()).start();
new Thread(test4.new Consumer()).start();
new Thread(test4.new Producer()).start();
new Thread(test4.new Consumer()).start();
}
class Producer implements Runnable {
@Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
try {
notFull.acquire();
mutex.acquire();
count++;
System.out.println(Thread.currentThread().getName()
+ "生产者生产，目前总共有" + count);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
mutex.release();
notEmpty.release();
}
}
}
}
class Consumer implements Runnable {
@Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep(3000);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
try {
notEmpty.acquire();
mutex.acquire();
count--;
System.out.println(Thread.currentThread().getName()
+ "消费者消费，目前总共有" + count);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
mutex.release();
notFull.release();
}
}
}
}
}
管道输入输出流PipedInputStream 和PipedOutputStream实现
/**
* 使用管道实现生产者消费者模型
* @author ZGJ
* @date 2017年6月30日
*/
public class Test5 {
final PipedInputStream pis = new PipedInputStream();
final PipedOutputStream pos = new PipedOutputStream();
{
try {
pis.connect(pos);
} catch (IOException e) {
e.printStackTrace();
}
}
class Producer implements Runnable {
@Override
public void run() {
try {
while(true) {
Thread.sleep(1000);
int num = (int) (Math.random() * 255);
System.out.println(Thread.currentThread().getName() + "生产者生产了一个数字，该数字为： " + num);
pos.write(num);
pos.flush();
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
pos.close();
pis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
class Consumer implements Runnable {
@Override
public void run() {
try {
while(true) {
Thread.sleep(1000);
int num = pis.read();
System.out.println("消费者消费了一个数字，该数字为：" + num);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
pos.close();
pis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public static void main(String[] args) {
Test5 test5 = new Test5();
new Thread(test5.new Producer()).start();
new Thread(test5.new Consumer()).start();
}
}