android - Android共享的首选项更改侦听器即使在全局引用侦听器的情况下也不起作用

我有一个注册共享的首选项更改侦听器的服务。共享的首选项属于另一个应用程序，并且可以在世界范围内读取。尽管按照建议的here保留了侦听器的全局实例，但并未调用My onSharedPreferenceChanged（）。
该服务的代码如下：

public class ClientService extends Service {
public static FileObserver observer;
public static final String addr = "127.0.0.1";
public static final int port = 5001;
public Socket socket = null;
InputStream inputStream;
OutputStream outputStream;
String buffer = new String();
OnSharedPreferenceChangeListener listener;


@Override
public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub
    return null;
}
@Override
public void onDestroy() {
    // TODO Auto-generated method stub
    Log.d(MainActivity.TAG, "killing service");
    super.onDestroy();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    // TODO Auto-generated method stub
    Log.d(MainActivity.TAG, "Starting Activity");
    Context context = null;
    /*try {
        socket = new Socket(addr, port);
        inputStream = socket.getInputStream();
        outputStream = socket.getOutputStream();
    } catch (Exception e) {
        // TODO: handle exception
        e.printStackTrace();
        Log.e(MainActivity.TAG, "Error in opening Socket");
    }*/
    Log.d(MainActivity.TAG,"Carrying on...");

    final MyClientTask clientTask = new MyClientTask(addr, port);
    SharedPreferences sp = null;
    try {
        context = getApplicationContext().createPackageContext("net.osmand.plus", Context.MODE_WORLD_WRITEABLE);
    } catch (Exception e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
        Log.e(MainActivity.TAG,"OSMAnd Package not found");
    }

    if(context != null) {
        sp = context.getSharedPreferences("net.osmand.settings", Context.MODE_WORLD_READABLE);
        Log.d(MainActivity.TAG, ""+sp.getFloat("last_known_map_lat", 0));

        listener = new SharedPreferences.OnSharedPreferenceChangeListener() {

            @Override
            public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
                    String key) {
                // TODO Auto-generated method stub
                Log.d(MainActivity.TAG,"Shared preference "+key+" changed");
                if(key == "last_known_map_lat" || key == "last_known_map_lon") {
                    /* Send this via socket */
                    float data = sharedPreferences.getFloat(key, 0);

                    Log.d(MainActivity.TAG, "Sending data: "+data);
                    clientTask.execute(""+data);

                }
            }
        };
        sp.registerOnSharedPreferenceChangeListener(listener);
    }


    observer = new FileObserver("/data/data/net.osmand.plus/shared_prefs/net.osmand.settings.xml" ) {

        @Override
        public void onEvent(int event, String path) {
            // TODO Auto-generated method stub
            if(event  == FileObserver.MODIFY) {
                Log.d(MainActivity.TAG, "Changed");
            }
        }
    };

    return super.onStartCommand(intent, flags, startId);
}



public class MyClientTask extends AsyncTask<String, Void, Void> {

    String dstAddress;
    int dstPort;
    String response = "";

    MyClientTask(String addr, int port){
        dstAddress = addr;
        dstPort = port;
    }

    @Override
    protected Void doInBackground(String... buffer) {
        try {
            byte[] bytes = buffer[0].getBytes();
            //outputStream.write(bytes);
            Log.d(MainActivity.TAG, "blah");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;

    }

    @Override
    protected void onPostExecute(Void result) {

        super.onPostExecute(result);
    }

}

}

共享的首选项相关代码位于onStartCommand（）中。
任何人有任何线索怎么了？
请注意，在实际的Sharedpreferences文件中，当我看到使用adb shell时，可以观察到值的变化

最佳答案

context = getApplicationContext().createPackageContext("net.osmand.plus", Context.MODE_WORLD_WRITEABLE);

您的上下文为空
您的骗局仅使用“此”服务本身就是一个上下文
或者您可以尝试getSharedPreferences("net.osmand.settings", Context.MODE_WORLD_READABLE);