gecko/mobile/android/base/UiAsyncTask.java

87 lines
2.6 KiB
Java

/* -*- Mode: Java; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil; -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.gecko.util;
import android.os.Handler;
import android.os.Looper;
/**
* Executes a background task and publishes the result on the UI thread.
*
* The standard {@link android.os.AsyncTask} only runs onPostExecute on the
* thread it is constructed on, so this is a convenience class for creating
* tasks off the UI thread.
*/
public abstract class UiAsyncTask<Params, Progress, Result> {
private volatile boolean mCancelled = false;
private final Handler mBackgroundThreadHandler;
private static Handler sHandler;
/**
* Creates a new asynchronous task.
*
* @param backgroundThreadHandler the handler to execute the background task on
*/
public UiAsyncTask(Handler backgroundThreadHandler) {
mBackgroundThreadHandler = backgroundThreadHandler;
}
private static synchronized Handler getUiHandler() {
if (sHandler == null) {
sHandler = new Handler(Looper.getMainLooper());
}
return sHandler;
}
private final class BackgroundTaskRunnable implements Runnable {
private Params[] mParams;
public BackgroundTaskRunnable(Params... params) {
mParams = params;
}
@Override
public void run() {
final Result result = doInBackground(mParams);
getUiHandler().post(new Runnable() {
@Override
public void run() {
if (mCancelled)
onCancelled();
else
onPostExecute(result);
}
});
}
}
public final void execute(final Params... params) {
getUiHandler().post(new Runnable() {
@Override
public void run() {
onPreExecute();
mBackgroundThreadHandler.post(new BackgroundTaskRunnable(params));
}
});
}
@SuppressWarnings({"UnusedParameters"})
public final boolean cancel(boolean mayInterruptIfRunning) {
mCancelled = true;
return mCancelled;
}
public final boolean isCancelled() {
return mCancelled;
}
protected void onPreExecute() { }
protected void onPostExecute(Result result) { }
protected void onCancelled() { }
protected abstract Result doInBackground(Params... params);
}