生产者-消费者java
2015-09-10 11:24
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生产者-消费者(producer-consumer)问题,也称作有界缓冲区(bounded-buffer)问题,两个进程共享一个公共的固定大小的缓冲区。其中一个是生产者,用于将消息放入缓冲区;另外一个是消费者,用于从缓冲区中取出消息。问题出现在当缓冲区已经满了,而此时生产者还想向其中放入一个新的数据项的情形,其解决方法是让生产者此时进行休眠,等待消费者从缓冲区中取走了一个或者多个数据后再去唤醒它。同样地,当缓冲区已经空了,而消费者还想去取消息,此时也可以让消费者进行休眠,等待生产者放入一个或者多个数据时再唤醒它。
一,首先定义公共资源类,其中的变量number是保存的公共数据。并且定义两个方法,增加number的值和减少number的值。由于多线程的原因,必须加上synchronized关键字,注意while判断的条件。
Java代码
/**
* 公共资源类
*/
public class PublicResource {
private int number = 0;
/**
* 增加公共资源
*/
public synchronized void increace() {
while (number != 0) {
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
number++;
System.out.println(number);
notify();
}
/**
* 减少公共资源
*/
public synchronized void decreace() {
while (number == 0) {
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
number--;
System.out.println(number);
notify();
}
}
二,分别定义生产者线程和消费者线程,并模拟多次生产和消费,即增加和减少公共资源的number值
Java代码
/**
* 生产者线程,负责生产公共资源
*/
public class ProducerThread implements Runnable {
private PublicResource resource;
public ProducerThread(PublicResource resource) {
this.resource = resource;
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep((long) (Math.random() * 1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
resource.increace();
}
}
}
/**
* 消费者线程,负责消费公共资源
*/
public class ConsumerThread implements Runnable {
private PublicResource resource;
public ConsumerThread(PublicResource resource) {
this.resource = resource;
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep((long) (Math.random() * 1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
resource.decreace();
}
}
}
三,模拟多个生产者和消费者操作公共资源的情形,结果须保证是在允许的范围内。
Java代码
public class ProducerConsumerTest {
public static void main(String[] args) {
PublicResource resource = new PublicResource();
new Thread(new ProducerThread(resource)).start();
new Thread(new ConsumerThread(resource)).start();
new Thread(new ProducerThread(resource)).start();
new Thread(new ConsumerThread(resource)).start();
new Thread(new ProducerThread(resource)).start();
new Thread(new ConsumerThread(resource)).start();
}
}
一,首先定义公共资源类,其中的变量number是保存的公共数据。并且定义两个方法,增加number的值和减少number的值。由于多线程的原因,必须加上synchronized关键字,注意while判断的条件。
Java代码
/**
* 公共资源类
*/
public class PublicResource {
private int number = 0;
/**
* 增加公共资源
*/
public synchronized void increace() {
while (number != 0) {
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
number++;
System.out.println(number);
notify();
}
/**
* 减少公共资源
*/
public synchronized void decreace() {
while (number == 0) {
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
number--;
System.out.println(number);
notify();
}
}
/** * 公共资源类 */ public class PublicResource { private int number = 0; /** * 增加公共资源 */ public synchronized void increace() { while (number != 0) { try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } } number++; System.out.println(number); notify(); } /** * 减少公共资源 */ public synchronized void decreace() { while (number == 0) { try { wait(); } catch (InterruptedException e) { e.printStackTrace(); } } number--; System.out.println(number); notify(); } }
二,分别定义生产者线程和消费者线程,并模拟多次生产和消费,即增加和减少公共资源的number值
Java代码
/**
* 生产者线程,负责生产公共资源
*/
public class ProducerThread implements Runnable {
private PublicResource resource;
public ProducerThread(PublicResource resource) {
this.resource = resource;
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep((long) (Math.random() * 1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
resource.increace();
}
}
}
/**
* 消费者线程,负责消费公共资源
*/
public class ConsumerThread implements Runnable {
private PublicResource resource;
public ConsumerThread(PublicResource resource) {
this.resource = resource;
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep((long) (Math.random() * 1000));
} catch (InterruptedException e) {
e.printStackTrace();
}
resource.decreace();
}
}
}
/** * 生产者线程,负责生产公共资源 */ public class ProducerThread implements Runnable { private PublicResource resource; public ProducerThread(PublicResource resource) { this.resource = resource; } @Override public void run() { for (int i = 0; i < 10; i++) { try { Thre 4000 ad.sleep((long) (Math.random() * 1000)); } catch (InterruptedException e) { e.printStackTrace(); } resource.increace(); } } } /** * 消费者线程,负责消费公共资源 */ public class ConsumerThread implements Runnable { private PublicResource resource; public ConsumerThread(PublicResource resource) { this.resource = resource; } @Override public void run() { for (int i = 0; i < 10; i++) { try { Thread.sleep((long) (Math.random() * 1000)); } catch (InterruptedException e) { e.printStackTrace(); } resource.decreace(); } } }
三,模拟多个生产者和消费者操作公共资源的情形,结果须保证是在允许的范围内。
Java代码
public class ProducerConsumerTest {
public static void main(String[] args) {
PublicResource resource = new PublicResource();
new Thread(new ProducerThread(resource)).start();
new Thread(new ConsumerThread(resource)).start();
new Thread(new ProducerThread(resource)).start();
new Thread(new ConsumerThread(resource)).start();
new Thread(new ProducerThread(resource)).start();
new Thread(new ConsumerThread(resource)).start();
}
}
public class ProducerConsumerTest { public static void main(String[] args) { PublicResource resource = new PublicResource(); new Thread(new ProducerThread(resource)).start(); new Thread(new ConsumerThread(resource)).start(); new Thread(new ProducerThread(resource)).start(); new Thread(new ConsumerThread(resource)).start(); new Thread(new ProducerThread(resource)).start(); new Thread(new ConsumerThread(resource)).start(); } }http://tanlan.iteye.com/blog/1158154
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