Java 如何使用锁定和一个条件暂停/恢复？

我正在尝试实现一个图像缓存系统，它将在向缓存中插入5个图像后暂停

public void run() {
    int index = 0;
    lock.lock();
    try {
        while (index < list.getJpegCount() && !bCancel) {
            String file = list.getJpeg(index);
            images.put(file,
                    ImageUtils.getThumbNail(list.getJpeg(index), size));
            index++;
            batchCount++;
            Console.writeLine("Object cached: " + file);
            if (batchCount > 5) {
                try {
                    batchCount = 0;
                    Console.writeLine("Waiting for next batch...");
                    bufferEmpty.await();
                    Console.writeLine("We are back...");
                } catch (InterruptedException ex) {
                    Logger.getLogger(JpegCache.class.getName()).log(
                            Level.SEVERE, null, ex);
                }
            }
        }
    } finally {
        lock.unlock();
    }
}

怎么了？

解决方案：

我忘记开锁了：

public Image getNext()
{        
    lock.lock();
    currentIndex++; 
    String filename=list.getJpeg(currentIndex);
    if (!images.containsKey(filename))
    {
        bufferEmpty.signalAll();
        lock.unlock();
        Console.writeLine("Start next batch...");
        return ImageUtils.getThumbNail(filename, size);           

    }else
    {
        lock.unlock();
        return images.get(filename);
    }
}

---

如何获得

bufferEmpty

条件？如：final Lock=new ReentrantLock（）；最终条件bufferEmpty=lock.newCondition（）；我最近在这里发布了一个机制。这可能很有趣。你的代码太复杂了。应该有一种更简单的方法使用监视器唤醒线程。您应该始终在finally块中解锁！

public Image getNext()
{        
    lock.lock();
    currentIndex++; 
    String filename=list.getJpeg(currentIndex);
    if (!images.containsKey(filename))
    {
        bufferEmpty.signalAll();
        lock.unlock();
        Console.writeLine("Start next batch...");
        return ImageUtils.getThumbNail(filename, size);           

    }else
    {
        lock.unlock();
        return images.get(filename);
    }
}