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Diffstat (limited to 'platform/android/src/com/artifex/mupdfdemo/AsyncTask.java')
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diff --git a/platform/android/src/com/artifex/mupdfdemo/AsyncTask.java b/platform/android/src/com/artifex/mupdfdemo/AsyncTask.java deleted file mode 100644 index b370794c..00000000 --- a/platform/android/src/com/artifex/mupdfdemo/AsyncTask.java +++ /dev/null @@ -1,670 +0,0 @@ -/* - * Copyright (C) 2008 The Android Open Source Project - * - * Licensed under the Apache License, Version 2.0 (the "License"); - * you may not use this file except in compliance with the License. - * You may obtain a copy of the License at - * - * http://www.apache.org/licenses/LICENSE-2.0 - * - * Unless required by applicable law or agreed to in writing, software - * distributed under the License is distributed on an "AS IS" BASIS, - * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - * See the License for the specific language governing permissions and - * limitations under the License. - */ - -package com.artifex.mupdfdemo; - -import java.util.concurrent.BlockingQueue; -import java.util.concurrent.Callable; -import java.util.concurrent.CancellationException; -import java.util.concurrent.ExecutionException; -import java.util.concurrent.Executor; -import java.util.concurrent.FutureTask; -import java.util.concurrent.LinkedBlockingQueue; -import java.util.concurrent.ThreadFactory; -import java.util.concurrent.ThreadPoolExecutor; -import java.util.concurrent.TimeUnit; -import java.util.concurrent.TimeoutException; -import java.util.concurrent.atomic.AtomicBoolean; -import java.util.concurrent.atomic.AtomicInteger; - -import android.os.Process; -import android.os.Handler; -import android.os.Message; - -/** - * <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 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 Executor}, - * {@link ThreadPoolExecutor} and {@link 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.</p> - * </div> - * - * <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:</p> - * <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; - * } - * - * protected void onProgressUpdate(Integer... progress) { - * setProgressPercent(progress[0]); - * } - * - * protected void onPostExecute(Long result) { - * showDialog("Downloaded " + result + " bytes"); - * } - * } - * </pre> - * - * <p>Once created, a task is executed very simply:</p> - * <pre class="prettyprint"> - * new DownloadFilesTask().execute(url1, url2, url3); - * </pre> - * - * <h2>AsyncTask's generic types</h2> - * <p>The three types used by an asynchronous task are the following:</p> - * <ol> - * <li><code>Params</code>, the type of the parameters sent to the task upon - * execution.</li> - * <li><code>Progress</code>, the type of the progress units published during - * the background computation.</li> - * <li><code>Result</code>, the type of the result of the background - * computation.</li> - * </ol> - * <p>Not all types are always used by an asynchronous task. To mark a type as unused, - * simply use the type {@link Void}:</p> - * <pre> - * private class MyTask extends AsyncTask<Void, Void, Void> { ... } - * </pre> - * - * <h2>The 4 steps</h2> - * <p>When an asynchronous task is executed, the task goes through 4 steps:</p> - * <ol> - * <li>{@link #onPreExecute()}, invoked on the UI thread before 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> - * <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> - * <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> - * <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.</li> - * </ol> - * - * <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:</p> - * <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> - * <li>The task instance must be created on the UI thread.</li> - * <li>{@link #execute} must be invoked on the UI thread.</li> - * <li>Do not call {@link #onPreExecute()}, {@link #onPostExecute}, - * {@link #doInBackground}, {@link #onProgressUpdate} manually.</li> - * <li>The task can be executed only once (an exception will be thrown if - * a second execution is attempted.)</li> - * </ul> - * - * <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.</p> - * <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> - * - * <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> - * <p>If you truly want parallel execution, you can invoke - * {@link #executeOnExecutor(java.util.concurrent.Executor, Object[])} with - * {@link #THREAD_POOL_EXECUTOR}.</p> - */ -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 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); - - /** - * An {@link 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 = new SerialExecutor(); - - 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(); - - 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 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. - * - * 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 - */ - protected void onPreExecute() { - } - - /** - * <p>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.</p> - * - * @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) { - } - - /** - * <p>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>.</p> - * - * @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(); - } - - /** - * <p>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.</p> - * - * @see #onCancelled(Object) - * @see #cancel(boolean) - * @see #isCancelled() - */ - 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(); - } - - /** - * <p>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.</p> - * - * @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 CancellationException If the computation was cancelled. - * @throws 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 CancellationException If the computation was cancelled. - * @throws ExecutionException If the computation threw an exception. - * @throws InterruptedException If the current thread was interrupted - * while waiting. - * @throws 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>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>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 AsyncTask.Status#RUNNING} or {@link 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>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 Executor} for custom - * behavior. - * - * <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>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 AsyncTask.Status#RUNNING} or {@link 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. - * - * {@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 static abstract 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; - } - } -} |