Java tutorial
/* * Copyright (C) 2014 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 android.app.job; import android.app.Service; import android.content.Intent; import android.os.IBinder; /** * <p>Entry point for the callback from the {@link android.app.job.JobScheduler}.</p> * <p>This is the base class that handles asynchronous requests that were previously scheduled. You * are responsible for overriding {@link JobService#onStartJob(JobParameters)}, which is where * you will implement your job logic.</p> * <p>This service executes each incoming job on a {@link android.os.Handler} running on your * application's main thread. This means that you <b>must</b> offload your execution logic to * another thread/handler/{@link android.os.AsyncTask} of your choosing. Not doing so will result * in blocking any future callbacks from the JobManager - specifically * {@link #onStopJob(android.app.job.JobParameters)}, which is meant to inform you that the * scheduling requirements are no longer being met.</p> */ public abstract class JobService extends Service { private static final String TAG = "JobService"; /** * Job services must be protected with this permission: * * <pre class="prettyprint"> * <service android:name="MyJobService" * android:permission="android.permission.BIND_JOB_SERVICE" > * ... * </service> * </pre> * * <p>If a job service is declared in the manifest but not protected with this * permission, that service will be ignored by the system. */ public static final String PERMISSION_BIND = "android.permission.BIND_JOB_SERVICE"; private JobServiceEngine mEngine; /** @hide */ public final IBinder onBind(Intent intent) { if (mEngine == null) { mEngine = new JobServiceEngine(this) { @Override public boolean onStartJob(JobParameters params) { return JobService.this.onStartJob(params); } @Override public boolean onStopJob(JobParameters params) { return JobService.this.onStopJob(params); } }; } return mEngine.getBinder(); } /** * Call this to inform the JobScheduler that the job has finished its work. When the * system receives this message, it releases the wakelock being held for the job. * <p> * You can request that the job be scheduled again by passing {@code true} as * the <code>wantsReschedule</code> parameter. This will apply back-off policy * for the job; this policy can be adjusted through the * {@link android.app.job.JobInfo.Builder#setBackoffCriteria(long, int)} method * when the job is originally scheduled. The job's initial * requirements are preserved when jobs are rescheduled, regardless of backed-off * policy. * <p class="note"> * A job running while the device is dozing will not be rescheduled with the normal back-off * policy. Instead, the job will be re-added to the queue and executed again during * a future idle maintenance window. * </p> * * @param params The parameters identifying this job, as supplied to * the job in the {@link #onStartJob(JobParameters)} callback. * @param wantsReschedule {@code true} if this job should be rescheduled according * to the back-off criteria specified when it was first scheduled; {@code false} * otherwise. */ public final void jobFinished(JobParameters params, boolean wantsReschedule) { mEngine.jobFinished(params, wantsReschedule); } /** * Called to indicate that the job has begun executing. Override this method with the * logic for your job. Like all other component lifecycle callbacks, this method executes * on your application's main thread. * <p> * Return {@code true} from this method if your job needs to continue running. If you * do this, the job remains active until you call * {@link #jobFinished(JobParameters, boolean)} to tell the system that it has completed * its work, or until the job's required constraints are no longer satisfied. For * example, if the job was scheduled using * {@link JobInfo.Builder#setRequiresCharging(boolean) setRequiresCharging(true)}, * it will be immediately halted by the system if the user unplugs the device from power, * the job's {@link #onStopJob(JobParameters)} callback will be invoked, and the app * will be expected to shut down all ongoing work connected with that job. * <p> * The system holds a wakelock on behalf of your app as long as your job is executing. * This wakelock is acquired before this method is invoked, and is not released until either * you call {@link #jobFinished(JobParameters, boolean)}, or after the system invokes * {@link #onStopJob(JobParameters)} to notify your job that it is being shut down * prematurely. * <p> * Returning {@code false} from this method means your job is already finished. The * system's wakelock for the job will be released, and {@link #onStopJob(JobParameters)} * will not be invoked. * * @param params Parameters specifying info about this job, including the optional * extras configured with {@link JobInfo.Builder#setExtras(android.os.PersistableBundle). * This object serves to identify this specific running job instance when calling * {@link #jobFinished(JobParameters, boolean)}. * @return {@code true} if your service will continue running, using a separate thread * when appropriate. {@code false} means that this job has completed its work. */ public abstract boolean onStartJob(JobParameters params); /** * This method is called if the system has determined that you must stop execution of your job * even before you've had a chance to call {@link #jobFinished(JobParameters, boolean)}. * * <p>This will happen if the requirements specified at schedule time are no longer met. For * example you may have requested WiFi with * {@link android.app.job.JobInfo.Builder#setRequiredNetworkType(int)}, yet while your * job was executing the user toggled WiFi. Another example is if you had specified * {@link android.app.job.JobInfo.Builder#setRequiresDeviceIdle(boolean)}, and the phone left its * idle maintenance window. You are solely responsible for the behavior of your application * upon receipt of this message; your app will likely start to misbehave if you ignore it. * <p> * Once this method returns, the system releases the wakelock that it is holding on * behalf of the job.</p> * * @param params The parameters identifying this job, as supplied to * the job in the {@link #onStartJob(JobParameters)} callback. * @return {@code true} to indicate to the JobManager whether you'd like to reschedule * this job based on the retry criteria provided at job creation-time; or {@code false} * to end the job entirely. Regardless of the value returned, your job must stop executing. */ public abstract boolean onStopJob(JobParameters params); }