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CyC2018 2018-04-09 12:32:53 +08:00
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@ -813,7 +813,7 @@ public class SemaphoreExample {
## FutureTask
在介绍 Callable 时我们知道它可以有返回值,返回值通过 Future 进行封装。FutureTask 实现了 RunnableFuture 接口,该接口继承自 Runnable 和 Future<V> 接口,这使得 FutureTask 既可以当做一个任务执行,也可以有返回值。
在介绍 Callable 时我们知道它可以有返回值,返回值通过 Future<V> 进行封装。FutureTask 实现了 RunnableFuture 接口,该接口继承自 Runnable 和 Future<V> 接口,这使得 FutureTask 既可以当做一个任务执行,也可以有返回值。
```java
public class FutureTask<V> implements RunnableFuture<V>
@ -823,7 +823,7 @@ public class FutureTask<V> implements RunnableFuture<V>
public interface RunnableFuture<V> extends Runnable, Future<V>
```
当一个计算任务需要执行很长时间,那么就可以用 FutureTask 来封装这个任务,用一个线程去执行该任务,然后执行其它任务。当需要该任务的计算结果时,再通过 FutureTask 的 get() 方法获取。
当一个计算任务需要执行很长时间,那么就可以用 FutureTask 来封装这个任务,用一个线程去执行该任务,然后其它线程继续执行其它任务。当需要该任务的计算结果时,再通过 FutureTask 的 get() 方法获取。
```java
public class FutureTaskExample {
@ -874,79 +874,54 @@ java.util.concurrent.BlockingQueue 接口有以下阻塞队列的实现:
**使用 BlockingQueue 实现生产者消费者问题**
```java
// 生产者
public class Producer implements Runnable {
private BlockingQueue<String> queue;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
public Producer(BlockingQueue<String> queue) {
this.queue = queue;
}
public class ProducerConsumer {
@Override
public void run() {
System.out.println(Thread.currentThread().getName() + " is making product.");
String product = "Made By " + Thread.currentThread().getName();
try {
queue.put(product);
} catch (InterruptedException e) {
e.printStackTrace();
private static BlockingQueue<String> queue = new ArrayBlockingQueue<>(5);
private static class Producer extends Thread {
@Override
public void run() {
queue.add("product");
System.out.print("produce..");
}
}
}
```
```java
// 消费者
public class Consumer implements Runnable {
private BlockingQueue<String> queue;
private static class Consumer extends Thread {
public Consumer(BlockingQueue<String> queue) {
this.queue = queue;
}
@Override
public void run() {
try {
String product = queue.take();
System.out.println(Thread.currentThread().getName() + " is consuming product." + "( " + product + " )");
} catch (InterruptedException e) {
e.printStackTrace();
@Override
public void run() {
try {
queue.take();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.print("consume..");
}
}
}
```
```java
// 客户端
public class Client {
public static void main(String[] args) {
BlockingQueue<String> queue = new LinkedBlockingQueue<>(5);
for (int i = 0; i < 2; i++) {
new Thread(new Consumer(queue), "Consumer-" + i).start();
Producer producer = new Producer();
producer.start();
}
for (int i = 0; i < 5; i++) {
// 只有两个 Product因此只能消费两个其它三个消费者被阻塞
new Thread(new Producer(queue), "Producer-" + i).start();
Consumer consumer = new Consumer();
consumer.start();
}
for (int i = 2; i < 5; i++) {
new Thread(new Consumer(queue), "Consumer-" + i).start();
for (int i = 0; i < 3; i++) {
Producer producer = new Producer();
producer.start();
}
}
}
```
```html
// 运行结果
Producer-0 is making product.
Consumer-0 is consuming product.( Made By Producer-0 )
Producer-1 is making product.
Consumer-1 is consuming product.( Made By Producer-1 )
Producer-2 is making product.
Producer-3 is making product.
Producer-4 is making product.
Consumer-2 is consuming product.( Made By Producer-2 )
Consumer-3 is consuming product.( Made By Producer-3 )
Consumer-4 is consuming product.( Made By Producer-4 )
produce..produce..consume..consume..produce..consume..produce..consume..produce..consume..
```