/** * Load an image specified by the data parameter into an ImageView (override {@link * ImageWorker#processBitmap(Object)} to define the processing logic). A memory and disk cache * will be used if an {@link ImageCache} has been set using {@link ImageWorker#addImageCache}. If * the image is found in the memory cache, it is set immediately, otherwise an {@link AsyncTask} * will be created to asynchronously load the bitmap. * * @param data The URL of the image to download. * @param imageView The ImageView to bind the downloaded image to. */ public void loadImage(Object data, ImageView imageView, Bitmap loadingBitmap) { if (data == null) { return; } Bitmap bitmap = null; if (mImageCache != null) { bitmap = mImageCache.getBitmapFromMemCache(String.valueOf(data)); } if (bitmap != null) { // Bitmap found in memory cache imageView.setImageBitmap(bitmap); } else if (cancelPotentialWork(data, imageView)) { final BitmapWorkerTask task = new BitmapWorkerTask(imageView); final AsyncDrawable asyncDrawable = new AsyncDrawable(mResources, loadingBitmap, task); imageView.setImageDrawable(asyncDrawable); if (UIUtils.hasHoneycomb()) { // On HC+ we execute on a dual thread executor. There really isn't much extra // benefit to having a really large pool of threads. Having more than one will // likely benefit network bottlenecks though. task.executeOnExecutor(DUAL_THREAD_EXECUTOR, data); } else { // Otherwise pre-HC the default is a thread pool executor (not ideal, serial // execution or a smaller number of threads would be better). task.execute(data); } } }
@TargetApi(Build.VERSION_CODES.HONEYCOMB) public static Set<String> getStringSet( final SharedPreferences pref, final String key, final Set<String> defaultValue) { if (UIUtils.hasHoneycomb()) { return pref.getStringSet(key, defaultValue); } else { final Set<String> set = new HashSet<String>(); int i = 0; Set<String> keySet = pref.getAll().keySet(); while (keySet.contains(key + i)) { set.add(pref.getString(key + i, "")); i++; } if (set.isEmpty()) { return defaultValue; } else { return set; } } }
/** * ************************************* Copied from JB release framework: * https://android.googlesource.com/platform/frameworks/base/+/jb-release/core/java/android/os/AsyncTask.java * * <p>so that threading behavior on all OS versions is the same and we can tweak behavior by using * executeOnExecutor() if needed. * * <p>There are 3 changes in this copy of AsyncTask: -pre-HC a single thread executor is used for * serial operation (Executors.newSingleThreadExecutor) and is the default -the default * THREAD_POOL_EXECUTOR was changed to use DiscardOldestPolicy -a new fixed thread pool called * DUAL_THREAD_EXECUTOR was added ************************************* * * <p> * * <p>AsyncTask enables proper and easy use of the UI thread. This class allows to perform * background operations and publish results on the UI thread without having to manipulate threads * and/or handlers. * * <p> * * <p>AsyncTask is designed to be a helper class around {@link Thread} and {@link * android.os.Handler} and does not constitute a generic threading framework. AsyncTasks should * ideally be used for short operations (a few seconds at the most.) If you need to keep threads * running for long periods of time, it is highly recommended you use the various APIs provided by * the <code>java.util.concurrent</code> pacakge such as {@link java.util.concurrent.Executor}, * {@link java.util.concurrent.ThreadPoolExecutor} and {@link java.util.concurrent.FutureTask}. * * <p> * * <p>An asynchronous task is defined by a computation that runs on a background thread and whose * result is published on the UI thread. An asynchronous task is defined by 3 generic types, called * <code>Params</code>, <code>Progress</code> and <code>Result</code>, and 4 steps, called <code> * onPreExecute</code>, <code>doInBackground</code>, <code>onProgressUpdate</code> and <code> * onPostExecute</code>. * * <p><div class="special reference"> * * <h3>Developer Guides</h3> * * <p>For more information about using tasks and threads, read the <a * href="{@docRoot}guide/topics/fundamentals/processes-and-threads.html">Processes and Threads</a> * developer guide. </div> * * <p> * * <h2>Usage</h2> * * <p>AsyncTask must be subclassed to be used. The subclass will override at least one method * ({@link #doInBackground}), and most often will override a second one ({@link #onPostExecute}.) * * <p> * * <p>Here is an example of subclassing: * * <pre class="prettyprint"> private class * DownloadFilesTask extends AsyncTask<URL, Integer, Long> { protected Long * doInBackground(URL... urls) { int count = urls.length; long totalSize = 0; for (int i = 0; i < * count; i++) { totalSize += Downloader.downloadFile(urls[i]); publishProgress((int) ((i / (float) * count) * 100)); // Escape early if cancel() is called if (isCancelled()) break; } return * totalSize; } * <p/> * protected void onProgressUpdate(Integer... progress) { setProgressPercent(progress[0]); } * <p/> * protected void onPostExecute(Long result) { showDialog("Downloaded " + result + " bytes"); } } * </pre> * * <p> * * <p>Once created, a task is executed very simply: * * <pre class="prettyprint"> new * DownloadFilesTask().execute(url1, url2, url3); </pre> * * <p> * * <h2>AsyncTask's generic types</h2> * * <p>The three types used by an asynchronous task are the following: * * <ol> * <li><code>Params</code>, the type of the parameters sent to the task upon execution. * <li><code>Progress</code>, the type of the progress units published during the background * computation. * <li><code>Result</code>, the type of the result of the background computation. * </ol> * * <p>Not all types are always used by an asynchronous task. To mark a type as unused, simply use * the type {@link Void}: * * <pre> private class MyTask extends * AsyncTask<Void, Void, Void> { ... } </pre> * * <p> * * <h2>The 4 steps</h2> * * <p>When an asynchronous task is executed, the task goes through 4 steps: * * <ol> * <li>{@link #onPreExecute()}, invoked on the UI thread immediately after the task is executed. * This step is normally used to setup the task, for instance by showing a progress bar in the * user interface. * <li>{@link #doInBackground}, invoked on the background thread immediately after {@link * #onPreExecute()} finishes executing. This step is used to perform background computation * that can take a long time. The parameters of the asynchronous task are passed to this step. * The result of the computation must be returned by this step and will be passed back to the * last step. This step can also use {@link #publishProgress} to publish one or more units of * progress. These values are published on the UI thread, in the {@link #onProgressUpdate} * step. * <li>{@link #onProgressUpdate}, invoked on the UI thread after a call to {@link * #publishProgress}. The timing of the execution is undefined. This method is used to display * any form of progress in the user interface while the background computation is still * executing. For instance, it can be used to animate a progress bar or show logs in a text * field. * <li>{@link #onPostExecute}, invoked on the UI thread after the background computation finishes. * The result of the background computation is passed to this step as a parameter. * </ol> * * <p> * * <h2>Cancelling a task</h2> * * <p>A task can be cancelled at any time by invoking {@link #cancel(boolean)}. Invoking this method * will cause subsequent calls to {@link #isCancelled()} to return true. After invoking this method, * {@link #onCancelled(Object)}, instead of {@link #onPostExecute(Object)} will be invoked after * {@link #doInBackground(Object[])} returns. To ensure that a task is cancelled as quickly as * possible, you should always check the return value of {@link #isCancelled()} periodically from * {@link #doInBackground(Object[])}, if possible (inside a loop for instance.) * * <p> * * <h2>Threading rules</h2> * * <p>There are a few threading rules that must be followed for this class to work properly: * * <ul> * <li>The AsyncTask class must be loaded on the UI thread. This is done automatically as of * {@link android.os.Build.VERSION_CODES#JELLY_BEAN}. * <li>The task instance must be created on the UI thread. * <li>{@link #execute} must be invoked on the UI thread. * <li>Do not call {@link #onPreExecute()}, {@link #onPostExecute}, {@link #doInBackground}, * {@link #onProgressUpdate} manually. * <li>The task can be executed only once (an exception will be thrown if a second execution is * attempted.) * </ul> * * <p> * * <h2>Memory observability</h2> * * <p>AsyncTask guarantees that all callback calls are synchronized in such a way that the following * operations are safe without explicit synchronizations. * * <ul> * <li>Set member fields in the constructor or {@link #onPreExecute}, and refer to them in {@link * #doInBackground}. * <li>Set member fields in {@link #doInBackground}, and refer to them in {@link * #onProgressUpdate} and {@link #onPostExecute}. * </ul> * * <p> * * <h2>Order of execution</h2> * * <p>When first introduced, AsyncTasks were executed serially on a single background thread. * Starting with {@link android.os.Build.VERSION_CODES#DONUT}, this was changed to a pool of threads * allowing multiple tasks to operate in parallel. Starting with {@link * android.os.Build.VERSION_CODES#HONEYCOMB}, tasks are executed on a single thread to avoid common * application errors caused by parallel execution. * * <p>If you truly want parallel execution, you can invoke {@link * #executeOnExecutor(java.util.concurrent.Executor, Object[])} with {@link #THREAD_POOL_EXECUTOR}. */ public abstract class AsyncTask<Params, Progress, Result> { private static final String LOG_TAG = "AsyncTask"; private static final int CORE_POOL_SIZE = 5; private static final int MAXIMUM_POOL_SIZE = 128; private static final int KEEP_ALIVE = 1; 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>(10); /** An {@link java.util.concurrent.Executor} that can be used to execute tasks in parallel. */ public static final Executor THREAD_POOL_EXECUTOR = new ThreadPoolExecutor( CORE_POOL_SIZE, MAXIMUM_POOL_SIZE, KEEP_ALIVE, TimeUnit.SECONDS, sPoolWorkQueue, sThreadFactory, new ThreadPoolExecutor.DiscardOldestPolicy()); /** * An {@link java.util.concurrent.Executor} that executes tasks one at a time in serial order. * This serialization is global to a particular process. */ public static final Executor SERIAL_EXECUTOR = UIUtils.hasHoneycomb() ? new SerialExecutor() : Executors.newSingleThreadExecutor(sThreadFactory); public static final Executor DUAL_THREAD_EXECUTOR = Executors.newFixedThreadPool(2, sThreadFactory); private static final int MESSAGE_POST_RESULT = 0x1; private static final int MESSAGE_POST_PROGRESS = 0x2; private static final InternalHandler sHandler = new InternalHandler(); private static volatile Executor sDefaultExecutor = SERIAL_EXECUTOR; 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(); @TargetApi(11) private static class SerialExecutor implements Executor { final ArrayDeque<Runnable> mTasks = new ArrayDeque<Runnable>(); Runnable mActive; public synchronized void execute(final Runnable r) { mTasks.offer( new Runnable() { public void run() { try { r.run(); } finally { scheduleNext(); } } }); if (mActive == null) { scheduleNext(); } } protected synchronized void scheduleNext() { if ((mActive = mTasks.poll()) != null) { THREAD_POOL_EXECUTOR.execute(mActive); } } } /** * Indicates the current status of the task. Each status will be set only once during the lifetime * of a task. */ public enum Status { /** Indicates that the task has not been executed yet. */ PENDING, /** Indicates that the task is running. */ RUNNING, /** Indicates that {@link uk.org.ngo.squeezer.util.AsyncTask#onPostExecute} has finished. */ FINISHED, } /** @hide Used to force static handler to be created. */ public static void init() { sHandler.getLooper(); } /** @hide */ public static void setDefaultExecutor(Executor exec) { sDefaultExecutor = exec; } /** Creates a new asynchronous task. This constructor must be invoked on the UI thread. */ public AsyncTask() { mWorker = new WorkerRunnable<Params, Result>() { public Result call() throws Exception { mTaskInvoked.set(true); Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND); //noinspection unchecked return postResult(doInBackground(mParams)); } }; mFuture = new FutureTask<Result>(mWorker) { @Override protected void done() { try { postResultIfNotInvoked(get()); } catch (InterruptedException e) { android.util.Log.w(LOG_TAG, e); } catch (ExecutionException e) { throw new RuntimeException( "An error occured while executing doInBackground()", e.getCause()); } catch (CancellationException e) { postResultIfNotInvoked(null); } } }; } private void postResultIfNotInvoked(Result result) { final boolean wasTaskInvoked = mTaskInvoked.get(); if (!wasTaskInvoked) { postResult(result); } } private Result postResult(Result result) { @SuppressWarnings("unchecked") Message message = sHandler.obtainMessage(MESSAGE_POST_RESULT, new AsyncTaskResult<Result>(this, result)); message.sendToTarget(); return result; } /** * Returns the current status of this task. * * @return The current status. */ public final Status getStatus() { return mStatus; } /** * Override this method to perform a computation on a background thread. The specified parameters * are the parameters passed to {@link #execute} by the caller of this task. * * <p>This method can call {@link #publishProgress} to publish updates on the UI thread. * * @param params The parameters of the task. * @return A result, defined by the subclass of this task. * @see #onPreExecute() * @see #onPostExecute * @see #publishProgress */ protected abstract Result doInBackground(Params... params); /** * Runs on the UI thread before {@link #doInBackground}. * * @see #onPostExecute * @see #doInBackground */ @SuppressWarnings("EmptyMethod") protected void onPreExecute() {} /** * Runs on the UI thread after {@link #doInBackground}. The specified result is the value returned * by {@link #doInBackground}. * * <p> * * <p>This method won't be invoked if the task was cancelled. * * @param result The result of the operation computed by {@link #doInBackground}. * @see #onPreExecute * @see #doInBackground * @see #onCancelled(Object) */ @SuppressWarnings({"UnusedDeclaration"}) protected void onPostExecute(Result result) {} /** * Runs on the UI thread after {@link #publishProgress} is invoked. The specified values are the * values passed to {@link #publishProgress}. * * @param values The values indicating progress. * @see #publishProgress * @see #doInBackground */ @SuppressWarnings({"UnusedDeclaration"}) protected void onProgressUpdate(Progress... values) {} /** * Runs on the UI thread after {@link #cancel(boolean)} is invoked and {@link * #doInBackground(Object[])} has finished. * * <p> * * <p>The default implementation simply invokes {@link #onCancelled()} and ignores the result. If * you write your own implementation, do not call <code>super.onCancelled(result)</code>. * * @param result The result, if any, computed in {@link #doInBackground(Object[])}, can be null * @see #cancel(boolean) * @see #isCancelled() */ @SuppressWarnings({"UnusedParameters"}) protected void onCancelled(Result result) { onCancelled(); } /** * Applications should preferably override {@link #onCancelled(Object)}. This method is invoked by * the default implementation of {@link #onCancelled(Object)}. * * <p> * * <p>Runs on the UI thread after {@link #cancel(boolean)} is invoked and {@link * #doInBackground(Object[])} has finished. * * @see #onCancelled(Object) * @see #cancel(boolean) * @see #isCancelled() */ @SuppressWarnings("EmptyMethod") protected void onCancelled() {} /** * Returns <tt>true</tt> if this task was cancelled before it completed normally. If you are * calling {@link #cancel(boolean)} on the task, the value returned by this method should be * checked periodically from {@link #doInBackground(Object[])} to end the task as soon as * possible. * * @return <tt>true</tt> if task was cancelled before it completed * @see #cancel(boolean) */ public final boolean isCancelled() { return mCancelled.get(); } /** * Attempts to cancel execution of this task. This attempt will fail if the task has already * completed, already been cancelled, or could not be cancelled for some other reason. If * successful, and this task has not started when <tt>cancel</tt> is called, this task should * never run. If the task has already started, then the <tt>mayInterruptIfRunning</tt> parameter * determines whether the thread executing this task should be interrupted in an attempt to stop * the task. * * <p> * * <p>Calling this method will result in {@link #onCancelled(Object)} being invoked on the UI * thread after {@link #doInBackground(Object[])} returns. Calling this method guarantees that * {@link #onPostExecute(Object)} is never invoked. After invoking this method, you should check * the value returned by {@link #isCancelled()} periodically from {@link * #doInBackground(Object[])} to finish the task as early as possible. * * @param mayInterruptIfRunning <tt>true</tt> if the thread executing this task should be * interrupted; otherwise, in-progress tasks are allowed to complete. * @return <tt>false</tt> if the task could not be cancelled, typically because it has already * completed normally; <tt>true</tt> otherwise * @see #isCancelled() * @see #onCancelled(Object) */ public final boolean cancel(boolean mayInterruptIfRunning) { mCancelled.set(true); return mFuture.cancel(mayInterruptIfRunning); } /** * Waits if necessary for the computation to complete, and then retrieves its result. * * @return The computed result. * @throws java.util.concurrent.CancellationException If the computation was cancelled. * @throws java.util.concurrent.ExecutionException If the computation threw an exception. * @throws InterruptedException If the current thread was interrupted while waiting. */ public final Result get() throws InterruptedException, ExecutionException { return mFuture.get(); } /** * Waits if necessary for at most the given time for the computation to complete, and then * retrieves its result. * * @param timeout Time to wait before cancelling the operation. * @param unit The time unit for the timeout. * @return The computed result. * @throws java.util.concurrent.CancellationException If the computation was cancelled. * @throws java.util.concurrent.ExecutionException If the computation threw an exception. * @throws InterruptedException If the current thread was interrupted while waiting. * @throws java.util.concurrent.TimeoutException If the wait timed out. */ public final Result get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException { return mFuture.get(timeout, unit); } /** * Executes the task with the specified parameters. The task returns itself (this) so that the * caller can keep a reference to it. * * <p> * * <p>Note: this function schedules the task on a queue for a single background thread or pool of * threads depending on the platform version. When first introduced, AsyncTasks were executed * serially on a single background thread. Starting with {@link * android.os.Build.VERSION_CODES#DONUT}, this was changed to a pool of threads allowing multiple * tasks to operate in parallel. Starting {@link android.os.Build.VERSION_CODES#HONEYCOMB}, tasks * are back to being executed on a single thread to avoid common application errors caused by * parallel execution. If you truly want parallel execution, you can use the {@link * #executeOnExecutor} version of this method with {@link #THREAD_POOL_EXECUTOR}; however, see * commentary there for warnings on its use. * * <p> * * <p>This method must be invoked on the UI thread. * * @param params The parameters of the task. * @return This instance of AsyncTask. * @throws IllegalStateException If {@link #getStatus()} returns either {@link * uk.org.ngo.squeezer.util.AsyncTask.Status#RUNNING} or {@link * uk.org.ngo.squeezer.util.AsyncTask.Status#FINISHED}. * @see #executeOnExecutor(java.util.concurrent.Executor, Object[]) * @see #execute(Runnable) */ public final AsyncTask<Params, Progress, Result> execute(Params... params) { return executeOnExecutor(sDefaultExecutor, params); } /** * Executes the task with the specified parameters. The task returns itself (this) so that the * caller can keep a reference to it. * * <p> * * <p>This method is typically used with {@link #THREAD_POOL_EXECUTOR} to allow multiple tasks to * run in parallel on a pool of threads managed by AsyncTask, however you can also use your own * {@link java.util.concurrent.Executor} for custom behavior. * * <p> * * <p><em>Warning:</em> Allowing multiple tasks to run in parallel from a thread pool is generally * <em>not</em> what one wants, because the order of their operation is not defined. For example, * if these tasks are used to modify any state in common (such as writing a file due to a button * click), there are no guarantees on the order of the modifications. Without careful work it is * possible in rare cases for the newer version of the data to be over-written by an older one, * leading to obscure data loss and stability issues. Such changes are best executed in serial; to * guarantee such work is serialized regardless of platform version you can use this function with * {@link #SERIAL_EXECUTOR}. * * <p> * * <p>This method must be invoked on the UI thread. * * @param exec The executor to use. {@link #THREAD_POOL_EXECUTOR} is available as a convenient * process-wide thread pool for tasks that are loosely coupled. * @param params The parameters of the task. * @return This instance of AsyncTask. * @throws IllegalStateException If {@link #getStatus()} returns either {@link * uk.org.ngo.squeezer.util.AsyncTask.Status#RUNNING} or {@link * uk.org.ngo.squeezer.util.AsyncTask.Status#FINISHED}. * @see #execute(Object[]) */ public final AsyncTask<Params, Progress, Result> executeOnExecutor( Executor exec, Params... params) { if (mStatus != Status.PENDING) { switch (mStatus) { case RUNNING: throw new IllegalStateException("Cannot execute task:" + " the task is already running."); case FINISHED: throw new IllegalStateException( "Cannot execute task:" + " the task has already been executed " + "(a task can be executed only once)"); } } mStatus = Status.RUNNING; onPreExecute(); mWorker.mParams = params; exec.execute(mFuture); return this; } /** * Convenience version of {@link #execute(Object...)} for use with a simple Runnable object. See * {@link #execute(Object[])} for more information on the order of execution. * * @see #execute(Object[]) * @see #executeOnExecutor(java.util.concurrent.Executor, Object[]) */ public static void execute(Runnable runnable) { sDefaultExecutor.execute(runnable); } /** * This method can be invoked from {@link #doInBackground} to publish updates on the UI thread * while the background computation is still running. Each call to this method will trigger the * execution of {@link #onProgressUpdate} on the UI thread. * * <p>{@link #onProgressUpdate} will note be called if the task has been canceled. * * @param values The progress values to update the UI with. * @see #onProgressUpdate * @see #doInBackground */ protected final void publishProgress(Progress... values) { if (!isCancelled()) { sHandler .obtainMessage(MESSAGE_POST_PROGRESS, new AsyncTaskResult<Progress>(this, values)) .sendToTarget(); } } private void finish(Result result) { if (isCancelled()) { onCancelled(result); } else { onPostExecute(result); } mStatus = Status.FINISHED; } private static class InternalHandler extends Handler { @SuppressWarnings({"unchecked", "RawUseOfParameterizedType"}) @Override public void handleMessage(Message msg) { AsyncTaskResult result = (AsyncTaskResult) msg.obj; switch (msg.what) { case MESSAGE_POST_RESULT: // There is only one result result.mTask.finish(result.mData[0]); break; case MESSAGE_POST_PROGRESS: result.mTask.onProgressUpdate(result.mData); break; } } } private abstract static class WorkerRunnable<Params, Result> implements Callable<Result> { Params[] mParams; } @SuppressWarnings({"RawUseOfParameterizedType"}) private static class AsyncTaskResult<Data> { final AsyncTask mTask; final Data[] mData; AsyncTaskResult(AsyncTask task, Data... data) { mTask = task; mData = data; } } }