无法获得对我的Service实例的引用以成功将其传递给处理程序

编程问答 2022-04-26

问题描述

|| 我将继续在Pro Android 2的此Service示例（第304页）上继续前进，该Service示例又由两个类组成：MainActivity.java和BackgroundService.java都如下所示。我最近的障碍是获取并使用对Service实例的引用，以成功将其传递给处理程序。 从网络搜索中，我发现了将处理程序传递给Service实例的丑陋方法，但这种方法不起作用。在此过程的下一步中，我将不胜感激-使它正常工作。请查看我在该文档下面的注释和代码，我试图通过绑定按钮（bindBtn）将处理程序传递给Service实例。 
    public class MainActivity extends Activity {
        private static final String TAG = \"MainActivity\";

        @Override
        public void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);

            Log.d(TAG,\"starting service\");

            Button bindBtn = (Button)findViewById(R.id.bindBtn);
            bindBtn.setonClickListener(new OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    Intent backgroundService = new Intent(MainActivity.this,com.marie.mainactivity.BackgroundService.class);
                    startService(backgroundService);

                    // wait until BackgroundService has started
                    while (BackgroundService.getInstance() == null);
                    // get instance of BackgroundService
                    BackgroundService sInstance = BackgroundService.getInstance();

                    // Now finally pass the handler to the Service              
                    sInstance.setHandler(handler);
                }
            });

            Button unbindBtn = (Button)findViewById(R.id.unbindBtn);
            unbindBtn.setonClickListener(new OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    stopService(new Intent(MainActivity.this,BackgroundService.class));
                }
            });
        }
    }

    // The handler to be passed to the Service
    private final Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            String msgObj = (String) msg.obj;
            int arg1 = msg.arg1;
            int arg2 = msg.arg2;
            int what = msg.what;
            Log.i(\"handleMessge\",\"msgObj: \" + msgObj + \",\" + \"arg1: \" + arg1 + \",\" + \"arg2: \" + arg2 + \",\" + \"what: \" + what);  
        }
    };
现在BackgroundService： 
    public class BackgroundService extends Service {
        private notificationmanager notificationMgr;

        private Handler mHandler;
        private static Service sInstance = null;

        @Override
        public void onCreate() {
            super.onCreate();

            notificationMgr = notificationmanager)getSystemService(NOTIFICATION_SERVICE);

            displayNotificationMessage(\"starting Background Service\");

            Thread thr = new Thread(null,new ServiceWorker(),\"BackgroundService\");
            thr.start();
        }   

        class ServiceWorker implements Runnable
        {
            public void run() {
                //Use the handler to send a message
                Message msg = new Message();
                msg.obj = \"msg obj\";
                msg.arg1 = 1;
                msg.arg2 = 2;
                msg.what = 3;
                mHandler.sendMessage(msg);

                //stop when done
                BackgroundService.this.stopSelf();
            }
        }

        @Override
        public void onDestroy()
        {
            displayNotificationMessage(\"stopping Background Service\");
            super.onDestroy();
        }

        @Override
        public void onStart(Intent intent,int startId) {
            super.onStart(intent,startId);
        }

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

        private void displayNotificationMessage(String message)
        {
            Notification notification = new Notification(R.drawable.note,message,System.currentTimeMillis());

            PendingIntent contentIntent = PendingIntent.getActivity(this,new Intent(this,MainActivity.class),0);

            notification.setLatestEventInfo(this,\"Background Service\",contentIntent);

            notificationMgr.notify(R.id.app_notification_id,notification);
        }
    }
我的目标是在使用绑定按钮（bindBtn）绑定到服务后，将处理程序传递给服务，并向处理程序发送一条消息。但是我在com.marie.mainactivity中得到了一个ANR：ERROR / ActivityManager（96）：ANR。显然，这似乎是将处理程序传递给Service的错误方法，因为它不起作用。 我正尝试在下面发布ANR的Logcat： 
D/MainActivity(24622): starting service

I/ActivityManager(   96): displayed com.marie.mainactivity/.MainActivity: +434ms

D/dalvikvm(23879): GC_EXPLICIT freed 5K,50% free 2740K/5379K,external 1625K/2137K,paused 79ms

D/dalvikvm(18736): GC_EXPLICIT freed 28K,49% free 2793K/5379K,paused 740ms

D/dalvikvm(18551): GC_EXPLICIT freed 32K,49% free 2967K/5767K,paused 583ms

D/dalvikvm(  192): GC_EXPLICIT freed 42K,53% free 3950K/8327K,external 12167K/12379K,paused 1000ms

W/ActivityManager(   96): Timeout executing service: ServiceRecord{4078d160 com.marie.mainactivity/.BackgroundService}

I/Process (   96): Sending signal. PID: 24622 SIG: 3

I/dalvikvm(24622): threadid=4: reacting to signal 3

I/dalvikvm(24622): Wrote stack traces to \'/data/anr/traces.txt\'

I/Process (   96): Sending signal. PID: 96 SIG: 3

I/dalvikvm(   96): threadid=4: reacting to signal 3

I/dalvikvm(   96): Wrote stack traces to \'/data/anr/traces.txt\'

I/Process (   96): Sending signal. PID: 184 SIG: 3

I/dalvikvm(  184): threadid=4: reacting to signal 3

I/dalvikvm(  184): Wrote stack traces to \'/data/anr/traces.txt\'

I/Process (   96): Sending signal. PID: 158 SIG: 3

I/dalvikvm(  158): threadid=4: reacting to signal 3

I/dalvikvm(  158): Wrote stack traces to \'/data/anr/traces.txt\'

D/dalvikvm(   96): GC_EXPLICIT freed 1045K,41% free 6408K/10759K,external 2855K/3554K,paused 126ms

E/ActivityManager(   96): ANR in com.marie.mainactivity

E/ActivityManager(   96): Reason: Executing service com.marie.mainactivity/.BackgroundService

E/ActivityManager(   96): Load: 2.86 / 2.27 / 1.69

E/ActivityManager(   96): cpu usage from 20840ms to 0ms ago:

E/ActivityManager(   96):   93% 24622/com.marie.mainactivity: 93% user + 0% kernel / faults: 536 minor

E/ActivityManager(   96):   1.4% 73/akmd: 0% user + 1.4% kernel

E/ActivityManager(   96):   0.5% 96/system_server: 0.2% user + 0.2% kernel / faults: 9 minor

E/ActivityManager(   96):   0.1% 23879/com.google.android.apps.uploader: 0.1% user + 0% kernel / faults: 49 minor

E/ActivityManager(   96):   0.1% 192/com.android.launcher: 0.1% user + 0% kernel / faults: 69 minor

E/ActivityManager(   96):   0.1% 18551/android.process.acore: 0.1% user + 0% kernel / faults: 54 minor

E/ActivityManager(   96):   0.1% 18736/android.process.media: 0.1% user + 0% kernel / faults: 49 minor

E/ActivityManager(   96):   0% 158/com.android.systemUI: 0% user + 0% kernel

E/ActivityManager(   96):   0% 5/events/0: 0% user + 0% kernel

E/ActivityManager(   96):   0% 48/synaptics_wq: 0% user + 0% kernel

E/ActivityManager(   96):   0% 56/ds2784-battery: 0% user + 0% kernel

E/ActivityManager(   96): 96% TOTAL: 96% user + 0.3% kernel

E/ActivityManager(   96): cpu usage from 378ms to 893ms later:

E/ActivityManager(   96):   94% 24622/com.marie.mainactivity: 94% user + 0% kernel

E/ActivityManager(   96):     94% 24622/ie.mainactivity: 94% user + 0% kernel

E/ActivityManager(   96):   3.8% 96/system_server: 1.9% user + 1.9% kernel

E/ActivityManager(   96):     3.8% 115/ActivityManager: 1.9% user + 1.9% kernel

E/ActivityManager(   96):   1.3% 73/akmd: 0% user + 1.3% kernel

E/ActivityManager(   96):     1.3% 24209/akmd: 0% user + 1.3% kernel

E/ActivityManager(   96): 100% TOTAL: 98% user + 1.9% kernel

I/Process (   96): Sending signal. PID: 24622 SIG: 9

W/ActivityManager(   96):   Force finishing activity com.marie.mainactivity/.MainActivity

I/ActivityManager(   96): Killing com.marie.mainactivity (pid=24622): user\'s request

I/ActivityManager(   96): Process com.marie.mainactivity (pid 24622) has died.

W/ActivityManager(   96): Service crashed 2 times,stopping: ServiceRecord{4078d160 com.marie.mainactivity/.BackgroundService}

I/WindowManager(   96): WIN DEATH: Window{407b7a70 com.marie.mainactivity/com.marie.mainactivity.MainActivity paused=true}

V/RenderScript_jni(  192): surfaceCreated

V/RenderScript_jni(  192): surfaceChanged

W/InputManagerService(   96): Got remoteexception sending setActive(false) notification to pid 24622 uid 10081

I/ActivityManager(   96): Start proc com.amazon.mp3 for service com.amazon.mp3/.service.DownloadService: pid=24632 uid=10055 gids={3003,1015}

I/ActivityThread(24632): Pub com.amazon.mp3.client.SearchSuggestionProvider: com.amazon.mp3.client.SearchSuggestionProvider

D/Configuration(24632): active site = local

D/FREESPACE(24632): Bytes to fill: 107900928

D/Configuration(24632): active site = remote

I/Gmail   (24587): calculateUnkNownSyncRationalesAndPurgeInBackground: queueing

I/Gmail   (24587): calculateUnkNownSyncRationalesAndPurgeInBackground: running

I/Gmail   (24587): MainSyncRequestProto: lowestBkwdConvoId: 0,highestHandledServerOp: 687539,normalSync: true

D/dalvikvm(24587): GC_CONCURRENT freed 1165K,54% free 3133K/6727K,paused 3ms+4ms

D/dalvikvm(24587): GC_CONCURRENT freed 617K,55% free 3081K/6727K,paused 11ms+2ms

D/dalvikvm(24587): GC_EXPLICIT freed 160K,55% free 3083K/6727K,paused 54ms

I/Gmail   (24587): MainSyncRequestProto: lowestBkwdConvoId: 0,highestHandledServerOp: 687616,normalSync: true

D/Gmail   (24587): Inserting message 1371513932623117837. synced=true

D/dalvikvm(24587): GC_EXPLICIT freed 123K,54% free 3127K/6727K,paused 63ms

I/Gmail   (24587): MainSyncRequestProto: lowestBkwdConvoId: 0,highestHandledServerOp: 687618,normalSync: true

I/Gmail   (24587): Sending notification intent: Intent { act=android.intent.action.PROVIDER_CHANGED dat=content://gmail-ls/unread/^i (has extras) }

I/AudioService(   96):  AudioFocus  requestAudioFocus() from android.media.AudioManager@4074e410

W/audioflinger(   68): write blocked for 167 msecs,27 delayed writes,thread 0xea00

I/AudioService(   96):  AudioFocus  abandonAudioFocus() from android.media.AudioManager@4074e410

D/AudioHardwareQSD(   68): AudioHardware pcm playback is going to standby.

D/dalvikvm(24587): GC_EXPLICIT freed 88K,54% free 3138K/6727K,paused 98ms

I/ActivityManager(   96): Start proc org.my_pod.mypod for service org.my_pod.mypod/net.robmunro.mypod.UpdateFeedsService: pid=24654 uid=10080 gids={3003,1015}

D/dalvikvm(   67): GC_EXPLICIT freed 11K,50% free 2717K/5379K,paused 68ms

D/dalvikvm(   67): GC_EXPLICIT freed <1K,paused 63ms

I/ActivityThread(24654): Pub org.my_pod.mypod: net.robmunro.mypod.util.MyPodContentProvider

D/dalvikvm(   67): GC_EXPLICIT freed <1K,paused 74ms
关于创建服务实例时我做错了什么的任何建议，以便我可以像处理程序一样传递给它，将不胜感激。     

解决方法

        我建议将ѭ3传递给服务，并使用它向
Handler
发送ѭ4。这是一个演示此情况的示例应用程序。     
serviceservice处理处理处理实例实例实例将其成功成功无法用以程序程序程序递给