Android 线程池（Android开发艺术探索）

最新推荐文章于 2024-04-22 00:53:34 发布

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本文详细介绍了Android中自定义线程池的实现方式，并列举了四种常见线程池：FixedThreadPool、CachedThreadPool、ScheduledThreadPool及SingleThreadExecutor的功能特性。通过具体代码展示了线程池参数配置与任务执行流程。

private static final int CORE_POOL_SIZE = CPU_COUNT + 1;//核心线程数
private static final int MAXIMUM_POOL_SIZE = CPU_COUNT * 2 + 1;//最大线程数
private static final long KEEP_ALIVE = 10L;//非核心线程超时时长

private static final ThreadFactory sThreadFactory = new ThreadFactory() {
    private final AtomicInteger mCount = new AtomicInteger(1);

    public Thread newThread(Runnable r) {
        return new Thread(r, "ImageLoader#" + mCount.getAndIncrement());
    }
};

public static final Executor THREAD_POOL_EXECUTOR = new ThreadPoolExecutor(
        CORE_POOL_SIZE, MAXIMUM_POOL_SIZE,
        KEEP_ALIVE, TimeUnit.SECONDS,
        new LinkedBlockingQueue<Runnable>(), sThreadFactory);

private Handler mMainHandler = new Handler(Looper.getMainLooper()) {
    @Override
    public void handleMessage(Message msg) {
        LoaderResult result = (LoaderResult) msg.obj;
        ImageView imageView = result.imageView;
        String uri = (String) imageView.getTag(TAG_KEY_URI);
        if (uri.equals(result.uri)) {
            imageView.setImageBitmap(result.bitmap);
        } else {
            Log.w(TAG, "set image bitmap,but url has changed, ignored!");
        }
    }
};

Runnable loadBitmapTask = new Runnable() {

    @Override
    public void run() {
        Bitmap bitmap = loadBitmap(uri, reqWidth, reqHeight);
        if (bitmap != null) {
            LoaderResult result = new LoaderResult(imageView, uri, bitmap);
            mMainHandler.obtainMessage(MESSAGE_POST_RESULT, result).sendToTarget();
        }
    }
};
THREAD_POOL_EXECUTOR.execute(loadBitmapTask);

Android中最常见的四类具有不同功能特性的线程池,它们都直接或间接地通过配置Thread poolexecutor来实现自己的功能特性,这四类线程池分别是 FixedThreadpoolCached，Cached ThreadPool, Scheduled Pool以及 SingleThreadExecutor。

public static ExecutorService newFixedThreadPool(int nThreads){
    return new ThreadPoolExecutor(nThreads, nThreads, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingDeque<Runnable>());
}