Java tutorial
/* * 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.binoy.vibhinna; import java.io.File; import android.app.Service; import android.content.ContentValues; import android.content.Intent; import android.os.Handler; import android.os.HandlerThread; import android.os.IBinder; import android.os.Looper; import android.os.Message; import android.provider.BaseColumns; import android.support.v4.content.LocalBroadcastManager; /** * IntentService is a base class for {@link Service}s that handle asynchronous * requests (expressed as {@link Intent}s) on demand. Clients send requests * through {@link android.content.Context#startService(Intent)} calls; the * service is started as needed, handles each Intent in turn using a worker * thread, and stops itself when it runs out of work. * <p> * This "work queue processor" pattern is commonly used to offload tasks from an * application's main thread. The IntentService class exists to simplify this * pattern and take care of the mechanics. To use it, extend IntentService and * implement {@link #onHandleIntent(Intent)}. IntentService will receive the * Intents, launch a worker thread, and stop the service as appropriate. * <p> * All requests are handled on a single worker thread -- they may take as long * as necessary (and will not block the application's main loop), but only one * request will be processed at a time. <div class="special reference"> * <h3>Developer Guides</h3> * <p> * For a detailed discussion about how to create services, read the <a * href="{@docRoot}guide/topics/fundamentals/services.html">Services</a> * developer guide. * </p> * </div> * * @see android.os.AsyncTask */ public abstract class CustomIntentService extends Service { private volatile Looper mServiceLooper; private volatile ServiceHandler mServiceHandler; private String mName; private boolean mRedelivery; static LocalBroadcastManager mLocalBroadcastManager; static Intent vfsListUpdatedIntent; static Intent tasksUpdatedIntent; private final class ServiceHandler extends Handler { // int intentId = 0; public ServiceHandler(Looper looper) { super(looper); } @Override public void handleMessage(Message msg) { Intent intent = (Intent) msg.obj; intent.putExtra("start_id", msg.arg1); onHandleIntent(intent); stopSelf(msg.arg1); } } /** * Creates an IntentService. Invoked by your subclass's constructor. * * @param name * Used to name the worker thread, important only for debugging. */ public CustomIntentService(String name) { super(); mName = name; } /** * Sets intent redelivery preferences. Usually called from the constructor * with your preferred semantics. * <p> * If enabled is true, {@link #onStartCommand(Intent, int, int)} will return * {@link Service#START_REDELIVER_INTENT}, so if this process dies before * {@link #onHandleIntent(Intent)} returns, the process will be restarted * and the intent redelivered. If multiple Intents have been sent, only the * most recent one is guaranteed to be redelivered. * <p> * If enabled is false (the default), * {@link #onStartCommand(Intent, int, int)} will return * {@link Service#START_NOT_STICKY}, and if the process dies, the Intent * dies along with it. */ public void setIntentRedelivery(boolean enabled) { mRedelivery = enabled; } @Override public void onCreate() { // TODO: It would be nice to have an option to hold a partial wakelock // during processing, and to have a static startService(Context, Intent) // method that would launch the service & hand off a wakelock. super.onCreate(); HandlerThread thread = new HandlerThread("IntentService[" + mName + "]"); thread.start(); mServiceLooper = thread.getLooper(); mServiceHandler = new ServiceHandler(mServiceLooper); } @Override public void onStart(Intent intent, int startId) { Message msg = mServiceHandler.obtainMessage(); msg.arg1 = startId; msg.obj = intent; mServiceHandler.sendMessage(msg); } /** * You should not override this method for your IntentService. Instead, * override {@link #onHandleIntent}, which the system calls when the * IntentService receives a start request. * * @see android.app.Service#onStartCommand */ @Override public int onStartCommand(Intent intent, int flags, int startId) { ContentValues values = new ContentValues(); if (intent.getIntExtra(VibhinnaService.TASK_TYPE, -1) == VibhinnaService.TASK_TYPE_NEW_VFS) values.put(DatabaseHelper.TASK_VS, VibhinnaUtils .avoidDuplicateFile(new File(intent.getStringExtra(VibhinnaService.FOLDER_PATH))).getName()); else values.put(DatabaseHelper.TASK_VS, new File(intent.getStringExtra(VibhinnaService.FOLDER_PATH)).getName()); values.put(DatabaseHelper.TASK_TYPE, intent.getIntExtra(VibhinnaService.TASK_TYPE, -1)); values.put(DatabaseHelper.TASK_STATUS, TasksAdapter.TASK_STATUS_WAITING); values.put(DatabaseHelper.TASK_MESSAGE, getString(R.string.task_message_waiting)); mLocalBroadcastManager = LocalBroadcastManager.getInstance(this); tasksUpdatedIntent = new Intent(); tasksUpdatedIntent.setAction(VibhinnaService.ACTION_TASK_QUEUE_UPDATED); mLocalBroadcastManager.sendBroadcast(tasksUpdatedIntent); vfsListUpdatedIntent = new Intent(VibhinnaService.ACTION_VFS_LIST_UPDATED); long id = Long .parseLong(getContentResolver().insert(TasksProvider.CONTENT_URI, values).getLastPathSegment()); intent.putExtra(BaseColumns._ID, id); onStart(intent, startId); return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY; } @Override public void onDestroy() { mServiceLooper.quit(); } /** * Unless you provide binding for your service, you don't need to implement * this method, because the default implementation returns null. * * @see android.app.Service#onBind */ @Override public IBinder onBind(Intent intent) { return null; } /** * This method is invoked on the worker thread with a request to process. * Only one Intent is processed at a time, but the processing happens on a * worker thread that runs independently from other application logic. So, * if this code takes a long time, it will hold up other requests to the * same IntentService, but it will not hold up anything else. When all * requests have been handled, the IntentService stops itself, so you should * not call {@link #stopSelf}. * * @param intent * The value passed to * {@link android.content.Context#startService(Intent)}. */ protected abstract void onHandleIntent(Intent intent); }