java concurrent Exchanger的例子

class DataBuffer {<br />private int count;<br />public static int MAX_SIZE = 100;</p><p>public DataBuffer(int count) {<br />this.count = count;<br />}</p><p>public synchronized boolean isFull() {<br />return count == MAX_SIZE;<br />}</p><p>public synchronized boolean isEmpty() {<br />return count == 0;<br />}</p><p>public void add(int offset) {<br />count += offset;<br />}</p><p>public void sub(int offset) {<br />count -= offset;<br />}</p><p>public int size() {<br />return count;<br />}</p><p>}</p><p>public class FillAndEmpty {<br />private Exchanger<DataBuffer> exchanger = new Exchanger<DataBuffer>();<br />private DataBuffer initialEmptyBuffer = new DataBuffer(0);<br />private DataBuffer initialFullBuffer = new DataBuffer(DataBuffer.MAX_SIZE);<br />private static final int step = 2;</p><p>private void addToBuffer(DataBuffer dataBuffer) {<br />dataBuffer.add(step);<br />}</p><p>private void takeFromBuffer(DataBuffer dataBuffer) {<br />dataBuffer.sub(step);<br />}</p><p>class FillingLoop implements Runnable {<br />public void run() {<br />DataBuffer currentBuffer = initialEmptyBuffer;<br />try {<br />while (currentBuffer != null) {<br />addToBuffer(currentBuffer);<br />if (currentBuffer.isFull()) {<br />currentBuffer = exchanger.exchange(currentBuffer);<br />System.out.println(currentBuffer + "/t"<br />+ "currentBuffer.isFull()");<br />}<br />}<br />} catch (InterruptedException ex) {<br />Thread.currentThread().interrupt();<br />}<br />}<br />}</p><p>class EmptyingLoop implements Runnable {<br />public void run() {<br />DataBuffer currentBuffer = initialFullBuffer;<br />try {<br />while (currentBuffer != null) {<br />takeFromBuffer(currentBuffer);<br />if (currentBuffer.isEmpty()) {<br />Thread.sleep(5000);<br />currentBuffer = exchanger.exchange(currentBuffer);<br />System.out.println(currentBuffer + "/t"<br />+ "currentBuffer.isEmpty()");<br />}<br />}<br />} catch (InterruptedException ex) {<br />Thread.currentThread().interrupt();<br />}<br />}<br />}</p><p>void start() {<br />new Thread(new FillingLoop()).start();<br />new Thread(new EmptyingLoop()).start();<br />}</p><p>public static void main(String[] args) {<br />new FillAndEmpty().start();<br />}<br />}<br />