Question

我从服务器上获取了大量图片，我想要获取一些优先级高于其他图片的图片，所以我实现了自己的ThreadPoolExecutor，它返回了一个实现的FutureTask Comparable但它似乎不起作用。这些任务或多或少按照我将它们添加到队列的顺序进行处理。我调试了BlockingQueue的{{1}}，发现当我添加ThreadPoolExecutor优先级更高时，它不会在队列顶部一直向上移动。这是代码

Runnable

我以这种方式将任务添加到池中：

public class PriorityThreadPoolExecutor extends ThreadPoolExecutor {

    public PriorityThreadPoolExecutor(int corePoolSize, int maximumPoolSize,
            long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
    }

    protected <T> RunnableFuture<T> newTaskForValue(Runnable runnable, T value) {
        return new ComparableFutureTask<T>(runnable, value);
    }

    protected class ComparableFutureTask<T> 
    extends FutureTask<T> implements Comparable<ComparableFutureTask<T>> {

        private Object object;

        public ComparableFutureTask(Runnable runnable, T result) {
            super(runnable, result);
            object = runnable;
        }

        @Override
        @SuppressWarnings({ "unchecked", "rawtypes" })
        public int compareTo(ComparableFutureTask<T> o) {
            if (this == o) {
                return 0;
            }
            if (o == null) {
                return -1; // this has higher priority than null
            }
            if (object != null && o.object != null) {
                if (object.getClass().equals(o.object.getClass())) {
                    if (object instanceof Comparable) {
                        return ((Comparable) object).compareTo(o.object);
                    }
                }
            }
            return 0;
        }
    }

}

我的public BitmapLoader(Context context){ mThreadPoolExecutor = new PriorityThreadPoolExecutor(10, Integer.MAX_VALUE,//corepool and maxpool 1L, TimeUnit.SECONDS,//keep alive idle threads new PriorityBlockingQueue<Runnable>());//priority queue for jobs } public void queuePhoto(String url, ImageView imageView, int priority) { BitmapToLoad p = new BitmapToLoad(url, imageView, priority); final RunnableFuture<Object> futureTask = mThreadPoolExecutor.newTaskForValue(new BitmapLoaderRunnable(p), null); Log.d("BitmapLoader", "Scheduling job with priority " + priority); mThreadPoolExecutor.execute(futureTask); }实现了BitmapLoaderRunnable，当我调试正在调用Comparable方法时。我究竟做错了什么？感谢

编辑：下面是我的runnables的代码

compareTo

Answer 1

PriorityQueue的头部是最少元素。因此，如果您首先需要最高优先级，则需要撤消比较。

    @Override
    public int compareTo(BitmapLoaderRunnable other) {
        return other.bitmapToLoad.priority - this.bitmapToLoad.priority;
    }

由PriorityBlockingQueue支持的ThreadPoolExecutor似乎不起作用

1 个答案: