使用回调从远程服务向 IPC 客户端发送数据时，Android AIDL 空指针异常

如何解决使用回调从远程服务向 IPC 客户端发送数据时，Android AIDL 空指针异常

我正在尝试通过 AIDL 将从 Rest API 调用获得的数据传递到另一个应用程序。当我将客户端配置为进行本地调用（相同的包名称）时，它可以工作，但是当我尝试将它与另一个应用程序包名称远程使用时，它返回一个空指针异常。如日志中所示，这两个服务有界并连接，但它仍然不起作用。我不确定我错过了什么。

更新：调试服务器端后，我知道它发送的回复错误来自 parceble 类。这是什么意思？

服务器代码：

package Aidl.Services;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

import java.lang.reflect.Type;
import java.util.ArrayList;

import Aidl.Library.ResultCallback;
import Aidl.Library.ServicesInterface;
import Main.MainActivity;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class AIDLServices extends Service {
    private static final String TAG = "AIDLServices";
    Gson gson;

    public AIDLServices() {
    }

    @Override
    public void onCreate() {
        super.onCreate();
        gson = new Gson();
        Log.d(TAG,"onCreate: Server Created");
    }

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

    private final ServicesInterface.Stub sBinder = new ServicesInterface.Stub() {

        /**
         * Checks services of main ambient and converts them into an jsonArray
         *
         * @param callback holds jsonArray of Services on callback
         * @return
         * @throws RemoteException
         */
        @Override
        public void getServices(ResultCallback callback) throws RemoteException {
            callback.onResult("CinemaAPP services");
        }

        @Override
        public void callService(String ServiceJsonString,ResultCallback callback) throws RemoteException {
            callback.onResult("CinemaAPP services");
        }
    };
}

客户代码：

public class AidlServicesUi extends AppCompatActivity {
    TextView getServices_txt;
    TextView getFriends_txt;
    TextView getVideo_txt;
    TextView getRestaurant_txt;
    private ServicesInterface ServicesInt;
    private AdditionServiceConnection connection;
    Gson gson;
    boolean mBound;
    private static final String TAG = "AidlServicesUi";

    class AdditionServiceConnection implements ServiceConnection {
        @Override
        public void onServiceConnected(ComponentName name,IBinder boundservice) {
            ServicesInt = ServicesInterface.Stub.asInterface((IBinder) boundservice);
            Log.d(TAG,"onServiceConnected() connected");
            mBound = true;
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            ServicesInt = null;
            Log.d(TAG,"onServiceDisconnected() disconnected");
            mBound=false;
        }
    }

    public void initService(String PackageName) {
        connection = new AdditionServiceConnection();
        Intent i = new Intent();
        i.setClassName(PackageName,"Aidl.Services.AIDLServices");
        boolean ret = bindService(i,connection,Context.BIND_AUTO_CREATE);
        mBound = ret;
        Log.d(TAG,"initService() bound with " + ret);
    }

    /**
     * Unbinds this activity from the AIDL Mobility service.
     */
    public void releaseService() {
        unbindService(connection);
        connection = null;
        Log.d(TAG,"releaseService() unbound.");
        mBound = false;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_aidl_services_ui);
        getServices_txt = findViewById(R.id.txt_get_services_respone_aidl);
        getFriends_txt = findViewById(R.id.txt_get_friends_services_respone_aidl);
        getVideo_txt = findViewById(R.id.txt_get_video_services_respone_aidl);
        getRestaurant_txt = findViewById(R.id.txt_get_restaurant_services_respone_aidl4);
        gson = new Gson();
        initService("com.muneeb.fypsaa.device");
    }

    @Override
    protected void onStart() {
        initService("com.muneeb.fypsaa.device");
        super.onStart();
    }

    @Override
    protected void onDestroy() {
        releaseService();
        super.onDestroy();
    }

    public void getServices(View view) throws RemoteException {
        ServicesInt.getServices(new ResultCallback() {
            @Override
            public void onResult(String result) throws RemoteException {
                MainActivity.parentServices = gson.fromJson(result,new TypeToken<ArrayList<Service>>(){}.getType());
            }

            @Override
            public IBinder asBinder() {
                return null;
            }
        });
    }

    public void FriendsService (View view) throws RemoteException {
        boolean found=false;
        for (int i =0;i<MainActivity.parentServices.size();i++){
            Service serv = MainActivity.parentServices.get(i);
            if(serv.ServiceName.equals("Friends Service")){
                found=true;
                String jsonFriendsService = gson.toJson(ServicesInt);
                ServicesInt.callService(jsonFriendsService,new ResultCallback(){
                    @Override
                    public void onResult(String result) throws RemoteException {
                        Type tp = new  TypeToken<ArrayList<String>>(){}.getType();
                        ArrayList<String> FriendsOnline = gson.fromJson(result,tp);
                        getFriends_txt.setText(FriendsOnline.toString());
                    }
                    @Override
                    public IBinder asBinder() {
                        return null;
                    }
                });
            }
        }
        if (found==false){
            getFriends_txt.setText("Service is not availible right now");
        }
    }

    public void VideoService (View view) throws RemoteException {
        boolean found=false;
        for (int i =0;i<MainActivity.parentServices.size();i++){
            Service serv = MainActivity.parentServices.get(i);
            if(serv.ServiceName.equals("Video Streaming Service")){
                found=true;
                String jsonFriendsService = gson.toJson(ServicesInt);
                ServicesInt.callService(jsonFriendsService,tp);
                        getFriends_txt.setText(FriendsOnline.toString());
                    }
                    @Override
                    public IBinder asBinder() {
                        return null;
                    }
                });
            }
        }
        if (found==false){
            getVideo_txt.setText("Service is not availible right now");
        }
    }

    public void RestaurantService (View view) throws RemoteException {
        boolean found=false;
        for (int i =0;i<MainActivity.parentServices.size();i++){
            Service serv = MainActivity.parentServices.get(i);
            if(serv.ServiceName.equals("Restaurant Service")){
                found=true;
                String jsonFriendsService = gson.toJson(ServicesInt);
                ServicesInt.callService(jsonFriendsService,tp);
                        getFriends_txt.setText(FriendsOnline.toString());
                    }
                    @Override
                    public IBinder asBinder() {
                        return null;
                    }
                });
            }
        }
        if (found==false){
            getRestaurant_txt.setText("Service is not availible right now");
        }
    }


}

AIDL 服务接口

import Aidl.Library.ResultCallback;

// Declare any non-default types here with import statements

interface ServicesInterface {
    /**
     * Demonstrates some basic types that you can use as parameters
     * and return values in AIDL.
     */
    void getServices(ResultCallback callback);
    void callService(String ServiceJsonString,ResultCallback callback);
}

AIDL 结果回调接口

interface ResultCallback {
    
    void onResult(String result);
}

错误日志

D/AidlMobilityUi: initService() bound with true
D/AidlMobilityUi: initService() bound with true
D/AidlMobilityUi: onServiceConnected() connected
D/AidlMobilityUi: onServiceConnected() connected
D/EGL_emulation: eglMakeCurrent: 0xec285360: ver 2 0 (tinfo 0xec283330)
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.muneeb.fypsaa.cinema,PID: 3116
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
        at android.view.View.performClick(View.java:6597)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
        at android.view.View.performClick(View.java:6597) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
     Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'void Aidl.Library.ResultCallback.onResult(java.lang.String)' on a null object reference
        at android.os.Parcel.createException(Parcel.java:1948)
        at android.os.Parcel.readException(Parcel.java:1910)
        at android.os.Parcel.readException(Parcel.java:1860)
        at Aidl.Library.MobilityInterface$Stub$Proxy.getSiblings(MobilityInterface.java:176)
        at Main.AidlMobilityUi.SendgetSiblingsRequest(AidlMobilityUi.java:130)
        at java.lang.reflect.Method.invoke(Native Method) 
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385) 
        at android.view.View.performClick(View.java:6597) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

使用回调从远程服务向 IPC 客户端发送数据时，Android AIDL 空指针异常

如何解决使用回调从远程服务向 IPC 客户端发送数据时，Android AIDL 空指针异常

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