多线程-生产者消费者（BlockingQueue实现）

标签：排序containsempty实现类nullexceptioncerrup导致

三、采用BlockingQueue实现

BlockingQueue也是java.util.concurrent下的主要用来控制线程同步的工具。

BlockingQueue有四个具体的实现类,根据不同需求,选择不同的实现类1、ArrayBlockingQueue：一个由数组支持的有界阻塞队列，规定大小的BlockingQueue,其构造函数必须带一个int参数来指明其大小.其所含的对象是以FIFO(先入先出)顺序排序的。

2、LinkedBlockingQueue：大小不定的BlockingQueue,若其构造函数带一个规定大小的参数,生成的BlockingQueue有大小限制,若不带大小参数,所生成的BlockingQueue的大小由Integer.MAX_VALUE来决定.其所含的对象是以FIFO(先入先出)顺序排序的。

3、PriorityBlockingQueue：类似于LinkedBlockQueue,但其所含对象的排序不是FIFO,而是依据对象的自然排序顺序或者是构造函数的Comparator决定的顺序。

4、SynchronousQueue：特殊的BlockingQueue,对其的操作必须是放和取交替完成的。

LinkedBlockingQueue 可以指定容量，也可以不指定，不指定的话，默认最大是Integer.MAX_VALUE,其中主要用到put和take方法，put方法在队列满的时候会阻塞直到有队列成员被消费，take方法在队列空的时候会阻塞，直到有队列成员被放进来。

import java.util.concurrent.BlockingQueue;

public class Producer implements Runnable {
BlockingQueue<String> queue;

public Producer(BlockingQueue<String> queue) {
this.queue = queue;
}

@Override
public void run() {
try {
String temp = \”A Product, 生产线程：\”
+ Thread.currentThread().getName();
System.out.println(\”I have made a product:\”
+ Thread.currentThread().getName());
queue.put(temp);//如果队列是满的话，会阻塞当前线程
} catch (InterruptedException e) {
e.printStackTrace();
}
}

}

import java.util.concurrent.BlockingQueue;

public class Consumer implements Runnable{
BlockingQueue<String> queue;

public Consumer(BlockingQueue<String> queue){
this.queue = queue;
}

@Override
public void run() {
try {
String temp = queue.take();//如果队列为空，会阻塞当前线程
System.out.println(temp);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

public class Test3 {

public static void main(String[] args) {
BlockingQueue<String> queue = new LinkedBlockingQueue<String>(2);
// BlockingQueue<String> queue = new LinkedBlockingQueue<String>();
//不设置的话，LinkedBlockingQueue默认大小为Integer.MAX_VALUE

// BlockingQueue<String> queue = new ArrayBlockingQueue<String>(2);

Consumer consumer = new Consumer(queue);
Producer producer = new Producer(queue);
for (int i = 0; i < 5; i++) {
new Thread(producer, \”Producer\” + (i + 1)).start();

new Thread(consumer, \”Consumer\” + (i + 1)).start();
}
}
}

BlockingQueue接口，扩展了Queue接口

package java.util.concurrent;

import java.util.Collection;
import java.util.Queue;

public interface BlockingQueue<E> extends Queue<E> {
boolean add(E e);

boolean offer(E e);

void put(E e) throws InterruptedException;

boolean offer(E e, long timeout, TimeUnit unit)
throws InterruptedException;
E take() throws InterruptedException;

E poll(long timeout, TimeUnit unit)
throws InterruptedException;

int remainingCapacity();

boolean remove(Object o);

public boolean contains(Object o);

int drainTo(Collection<? super E> c);

int drainTo(Collection<? super E> c, int maxElements);
}

我们用到的take() 和put(E e)

两个方法，在ArrayBlockingQueue中的实现

public void put(E e) throws InterruptedException {
if (e == null) throw new NullPointerException();
final E[] items = this.items;
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
try {
while (count == items.length)
notFull.await();
} catch (InterruptedException ie) {
notFull.signal(); // propagate to non-interrupted thread
throw ie;
}
insert(e);
} finally {
lock.unlock();
}
}