在同步块中调用 wait() 和 notify()方法，如果阻塞，通过循环来测试等待条件。请参考答案中的示例代码。
【生产者】
import java.util.Vector;
import java.util.logging.Level;
import java.util.logging.Logger; public class Producer implements Runnable { private final Vector sharedQueue;
private final int SIZE; public Producer(Vector sharedQueue, int size) {
this.sharedQueue = sharedQueue;
this.SIZE = size;
} @Override
public void run() {
// 生产数据
for (int i = 0; i < 7; i++) {
System.out.println("Produced:" + i);
try {
produce(i);
} catch (InterruptedException ex) {
Logger.getLogger(Producer.class.getName()).log(Level.SEVERE, null, ex);
}
}
} private void produce(int i) throws InterruptedException { // wait if queue is full
while (sharedQueue.size() == SIZE) {
synchronized (sharedQueue) {
System.out.println("Queue is full " + Thread.currentThread().getName()
+ " is waiting , size: " + sharedQueue.size());
sharedQueue.wait();
}
} // producing element and notify consumers
synchronized (sharedQueue) {
sharedQueue.add(i);
sharedQueue.notifyAll();
}
}
}
【消费者】
import java.util.Vector;
import java.util.logging.Level;
import java.util.logging.Logger; public class Consumer implements Runnable { private final Vector sharedQueue;
private final int SIZE; public Consumer(Vector sharedQueue, int size) {
this.sharedQueue = sharedQueue;
this.SIZE = size;
} @Override
public void run() {
// 消费数据
while (true) {
try {
System.out.println("Consumer: " + consume());
Thread.sleep(50);
} catch (InterruptedException ex) {
Logger.getLogger(Consumer.class.getName()).log(Level.SEVERE, null, ex);
}
}
} private int consume() throws InterruptedException { // wait if queue is empty
while (sharedQueue.isEmpty()) {
synchronized (sharedQueue) {
System.out.println("Queue is empty " + Thread.currentThread().getName()
+ " is waiting , size: " + sharedQueue.size());
sharedQueue.wait();
}
} //otherwise consume element and notify waiting producer
synchronized (sharedQueue) {
sharedQueue.notifyAll();
return (Integer) sharedQueue.remove(0);
}
}
}
【测试函数】
import java.util.Vector;
public class ProducerConsumerSolution {
public static void main(String[] args) {
Vector sharedQueue = new Vector();
int size = 4;
Thread prodThread = new Thread(new Producer(sharedQueue, size), "Producer");
Thread consThread = new Thread(new Consumer(sharedQueue, size), "Consumer");
prodThread.start();
consThread.start();
}
}
运行结果：
Produced:0
Queue is empty Consumer is waiting , size: 0
Produced:1
Consumer: 0
Produced:2
Produced:3
Produced:4
Produced:5
Queue is full Producer is waiting , size: 4
Consumer: 1
Produced:6
Queue is full Producer is waiting , size: 4
Consumer: 2
Consumer: 3
Consumer: 4
Consumer: 5
Consumer: 6
Queue is empty Consumer is waiting , size: 0