建立遠端服務（通過 AIDL）

通過 .aidl 檔案描述你的服務訪問介面：

// IRemoteService.aidl
package com.example.android;

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

/** Example service interface */
interface IRemoteService {
    /** Request the process ID of this service, to do evil things with it. */
    int getPid();
}

現在，在構建應用程式之後，sdk 工具將生成適當的 .java 檔案。這個檔案將包含 Stub 類，它實現了我們的 aidl 介面，我們需要擴充套件它：

public class RemoteService extends Service {

    private final IRemoteService.Stub binder = new IRemoteService.Stub() {
        @Override
        public int getPid() throws RemoteException {
            return Process.myPid();
        }
    };

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

然後在活動中：

public class MainActivity extends AppCompatActivity {
    private final ServiceConnection connection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            IRemoteService service = IRemoteService.Stub.asInterface(iBinder);
            Toast.makeText(this, "Activity process: " + Process.myPid + ", Service process: " + getRemotePid(service), LENGTH_SHORT).show();
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {}
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    protected void onStart() {
        super.onStart();
        Intent intent = new Intent(this, RemoteService.class);
        bindService(intent, connection, Context.BIND_AUTO_CREATE);
    }

    @Override
    protected void onStop() {
        super.onStop();
        unbindService(connection);
    }

    private int getRemotePid(IRemoteService service) {
        int result = -1;

        try {
            result = service.getPid();
        } catch (RemoteException e) {
            e.printStackTrace();
        }

        return result;
    }
}