Android必知必会的四大组件--Service

// 第一步：在AndroidManifest.xml中进行注册
<service android:name=".LocalService"/>

// 第二步：启动
① startService(Intent);
② bindService(Intent, ServiceConnection, Int);

// 第三步：解绑(使用方法② 启动时操作)
unBindService(ServiceConnection);

// 第四步：暂停
stopService(Intent);

/**
 * Service方法继承
 * onBind()是一个抽象方法。
 */
public class LocalService extends Service {
    private final IBinder binder = new ServiceBinder();

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return binder;
    }

    public class ServiceBinder extends Binder {
        LocalService getLocalService(){
            return LocalService.this;
        }
    }
}

/**
 * bindService()方法中的参数之一。
 * 用于对service进行操作
 */
ServiceConnection connection = new ServiceConnection() {
           // Activity和Service绑定时调用
            @Override
            public void onServiceConnected(ComponentName name, IBinder binder) {
                // 基于Binder拿到我们要的Service
                service = ((LocalService.ServiceBinder)binder).getLocalService();
                // 干你需要干的事情
            }
            // Activity和Service解绑时调用
            @Override
            public void onServiceDisconnected(ComponentName name) {
                service = null;
            }
        };

public class LocalIntentService extends IntentService {
    /**
     * Creates an IntentService.  Invoked by your subclass's constructor.
     *
     * @param name Used to name the worker thread, important only for debugging.
     */
    public LocalIntentService(String name) {
        super(name);
    }

    @Override
    protected void onHandleIntent(@Nullable Intent intent) {
        
    }
}

public abstract class IntentService extends Service {
    private volatile Looper mServiceLooper;
    @UnsupportedAppUsage
    private volatile ServiceHandler mServiceHandler;
    private String mName;
    private boolean mRedelivery;
    
    private final class ServiceHandler extends Handler {
        public ServiceHandler(Looper looper) {
            super(looper);
        }

        @Override
        public void handleMessage(Message msg) {
            onHandleIntent((Intent)msg.obj);
            stopSelf(msg.arg1);
        }
    }
}

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);
    }

public int onStartCommand(@Nullable Intent intent, int flags, int startId) {
        onStart(intent, startId); // 1 -->
        return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY; // 2 -->
    }

public void onStart(@Nullable Intent intent, int startId) {
        Message msg = mServiceHandler.obtainMessage();
        msg.arg1 = startId;
        msg.obj = intent;
        mServiceHandler.sendMessage(msg);
    }

/**
     * Constant to return from {@link #onStartCommand}: if this service's
     * process is killed while it is started (after returning from
     * {@link #onStartCommand}), and there are no new start intents to
     * deliver to it, then take the service out of the started state and
     * don't recreate until a future explicit call to
     * {@link Context#startService Context.startService(Intent)}.  The
     * service will not receive a {@link #onStartCommand(Intent, int, int)}
     * call with a null Intent because it will not be restarted if there
     * are no pending Intents to deliver.
     *
     * <p>This mode makes sense for things that want to do some work as a
     * result of being started, but can be stopped when under memory pressure
     * and will explicit start themselves again later to do more work.  An
     * example of such a service would be one that polls for data from
     * a server: it could schedule an alarm to poll every N minutes by having
     * the alarm start its service.  When its {@link #onStartCommand} is
     * called from the alarm, it schedules a new alarm for N minutes later,
     * and spawns a thread to do its networking.  If its process is killed
     * while doing that check, the service will not be restarted until the
     * alarm goes off.
     */
    public static final int START_NOT_STICKY = 2;

    /**
     * Constant to return from {@link #onStartCommand}: if this service's
     * process is killed while it is started (after returning from
     * {@link #onStartCommand}), then it will be scheduled for a restart
     * and the last delivered Intent re-delivered to it again via
     * {@link #onStartCommand}.  This Intent will remain scheduled for
     * redelivery until the service calls {@link #stopSelf(int)} with the
     * start ID provided to {@link #onStartCommand}.  The
     * service will not receive a {@link #onStartCommand(Intent, int, int)}
     * call with a null Intent because it will only be restarted if
     * it is not finished processing all Intents sent to it (and any such
     * pending events will be delivered at the point of restart).
     */
    public static final int START_REDELIVER_INTENT = 3;