AsyncTask使用总结

概述

AsyncTask是由Android封装的一个轻量级异步抽象类，可以在线程池中执行后台任务，然后把执行的进度和最终结果传递给主线程并在主线程中更新UI。AsynTask的源码如下：

public abstract class AsyncTask<Params, Progress, Result> {
    private static final String LOG_TAG = "AsyncTask";
    private static final int CPU_COUNT = Runtime.getRuntime().availableProcessors();
    private static final int CORE_POOL_SIZE = Math.max(2, Math.min(CPU_COUNT - 1, 4));
    private static final int MAXIMUM_POOL_SIZE = CPU_COUNT * 2 + 1;
    private static final int KEEP_ALIVE_SECONDS = 30;

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

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

    private static final BlockingQueue<Runnable> sPoolWorkQueue = new LinkedBlockingQueue<Runnable>(128);

    public static final Executor THREAD_POOL_EXECUTOR;

    static {
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(
                CORE_POOL_SIZE, MAXIMUM_POOL_SIZE, KEEP_ALIVE_SECONDS, TimeUnit.SECONDS,
                sPoolWorkQueue, sThreadFactory);
        threadPoolExecutor.allowCoreThreadTimeOut(true);
        THREAD_POOL_EXECUTOR = threadPoolExecutor;
    }


    public static final Executor SERIAL_EXECUTOR = new SerialExecutor();
    private static final int MESSAGE_POST_RESULT = 0x1;
    private static final int MESSAGE_POST_PROGRESS = 0x2;
    private static volatile Executor sDefaultExecutor = SERIAL_EXECUTOR;
    private static InternalHandler sHandler;
    private final WorkerRunnable<Params, Result> mWorker;
    private final FutureTask<Result> mFuture;
    private volatile Status mStatus = Status.PENDING;
    private final AtomicBoolean mCancelled = new AtomicBoolean();
    private final AtomicBoolean mTaskInvoked = new AtomicBoolean();
    private static