LocationClient auto reconnect at `onDisconnect`

问题

I tried to reconnect to LocationClient when the connection gets lost (When user clear the RAM).

I tried to use this code:

private final GooglePlayServicesClient.ConnectionCallbacks mConnectionCallback = new GooglePlayServicesClient.ConnectionCallbacks() {

    @Override
    public void onDisconnected() {
        mLocationClient.removeLocationUpdates(mLocationListener);
        mLocationClient.disconnect();
        mLocationClient= null;

        mLocationClient= new LocationClient(mContext, mConnectionCallback, mConnectionFailedCallback);
        mLocationClient.connect(); // NULL POINTER EXCEPTION
    }

    @Override
    public void onConnected(Bundle bundle) {
          ...
    }
};

But I get NullPointerException inside mLocaitonClient.connect().

10-15 08:33:26.478: E/AndroidRuntime(19572): FATAL EXCEPTION: main
10-15 08:33:26.478: E/AndroidRuntime(19572): java.lang.NullPointerException
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.internal.bh.a(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.internal.k.f(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.internal.k$e.onServiceConnected(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.internal.l.a(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.internal.k.connect(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.location.LocationClient.connect(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.myapp.MyLocationClient$1.onDisconnected(MyLocationClient.java:92)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.internal.k.A(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.internal.k$e.onServiceDisconnected(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.google.android.gms.internal.l$a$a.onServiceDisconnected(Unknown Source)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at android.app.LoadedApk$ServiceDispatcher.doDeath(LoadedApk.java:1102)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at android.app.LoadedApk$ServiceDispatcher$RunConnection.run(LoadedApk.java:1116)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at android.os.Handler.handleCallback(Handler.java:615)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at android.os.Handler.dispatchMessage(Handler.java:92)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at android.os.Looper.loop(Looper.java:137)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at android.app.ActivityThread.main(ActivityThread.java:4898)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at java.lang.reflect.Method.invokeNative(Native Method)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at java.lang.reflect.Method.invoke(Method.java:511)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
10-15 08:33:26.478: E/AndroidRuntime(19572):    at dalvik.system.NativeStart.main(Native Method)

How can I fix it and reconnect?

回答1:

an even simpler solution is to do nothing in the OnDisconnect.

public void onDisconnect(){
     //do nothing to client
}

when need to use the client simply check if is connected

if(mLocationClient.isconnected()){
     mLocationClient.connect();
}

the Google Play Services seems to reconnect nicely with out fuss.

i have used this on 4.0.4 and 4.2.2 successfully.

回答2:

I found the solution! Just use Handler.

@Override
public void onDisconnected() {

    new Handler().post(new Runnable() {
        @Override
        public void run() {
            mLocationClient.removeLocationUpdates(mLocationListener);
            mLocationClient.disconnect();
            mLocationClient = null;

            mLocationClient = new LocationClient(mContext, mConnectionCallback, mConnectionFailedCallback);
            mLocationClient.connect(); // NOW WORKING
        }
    }
}

回答3:

In the official documentation (http://developer.android.com/reference/com/google/android/gms/location/LocationClient.html), it's written that:

public void disconnect ()

"Closes the connection to Google Play services. No calls can be made on this object after calling this method."

So you cannot call a connect() just after, you have to recreate the LocationClient object like you did the first time in order to connect again.

来源：https://stackoverflow.com/questions/19373972/locationclient-auto-reconnect-at-ondisconnect