android - 使用相机拍照的后台服务

Question

我知道有很多关于此的问题，但我认为我面临的问题没有在其中得到解决。从所有不同的问题我写了这个服务。问题是我在 onStartCommand 方法的所有 try-catch block 中都获得了“成功”，但是 Callback 方法(ShutterCallback 和 PictureCallback)中的日志没有得到处理。我认为这意味着已拍摄照片但未调用回调，这很奇怪。

Camera cam;
Parameters param;
PictureCallback rawCallback = new PictureCallback() {
    public void onPictureTaken(byte[] data, Camera camera) {
        Log.d("CAMERA", "onPictureTaken - raw");
    }
};

ShutterCallback shutterCallback = new ShutterCallback() {
    public void onShutter() {
        Log.i("CAMERA", "onShutter'd");
    }
};

@Override
public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    try {
        cam = Camera.open();
        Log.i("CAMERA", "Success");
    } catch (RuntimeException e) {
        Log.e("CAMERA", "Camera currently unavailable");
        e.printStackTrace();
    }
    try {
        param = cam.getParameters();
        cam.setParameters(param);
        Log.i("CAMERA", "Success");
    } catch (Exception e1) {
        Log.e("CAMERA", "Parameter problem");
        e1.printStackTrace();
    }
    try {
        SurfaceView view = new SurfaceView(this);
        cam.setPreviewDisplay(view.getHolder());
        cam.startPreview();
        Log.i("CAMERA", "Success");
    } catch (Exception e) {
        Log.e("CAMERA", "Surface Problem");
        e.printStackTrace();
    }
    try {
        cam.takePicture(shutterCallback, rawCallback, null);
        Log.i("CAMERA", "Success");
    } catch (Exception e) {
        Log.e("CAMERA", "Click Failure");
        e.printStackTrace();
    }
    cam.release();
    return super.onStartCommand(intent, flags, startId);
}

Answer 1

调用 takePicture 方法后不应立即释放相机。您需要给相机足够的时间来执行回调。顺便说一句，你最好也添加一个 JPG 回调。也可以在释放相机之前调用 stopPreview。您的代码可能如下所示:

Camera cam;
Parameters param;
PictureCallback rawCallback = new PictureCallback() {
    public void onPictureTaken(byte[] data, Camera camera) {
        Log.d("CAMERA", "onPictureTaken - raw");
        camera.stopPreview();
        camera.release();
    }
};

PictureCallback jpgCallback = new PictureCallback() {
    public void onPictureTaken(byte[] data, Camera camera) {
        Log.d("CAMERA", "onPictureTaken - jpg");
        camera.stopPreview();
        camera.release();
    }
};

ShutterCallback shutterCallback = new ShutterCallback() {
    public void onShutter() {
        Log.i("CAMERA", "onShutter'd");
    }
};

@Override
public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    try {
        cam = Camera.open();
        Log.i("CAMERA", "Success");
    } catch (RuntimeException e) {
        Log.e("CAMERA", "Camera currently unavailable");
        e.printStackTrace();
    }
    try {
        param = cam.getParameters();
        cam.setParameters(param);
        Log.i("CAMERA", "Success");
    } catch (Exception e1) {
        Log.e("CAMERA", "Parameter problem");
        e1.printStackTrace();
    }
    try {
        SurfaceView view = new SurfaceView(this);
        cam.setPreviewDisplay(view.getHolder());
        cam.startPreview();
        Log.i("CAMERA", "Success");
    } catch (Exception e) {
        Log.e("CAMERA", "Surface Problem");
        e.printStackTrace();
    }
    try {
        cam.takePicture(shutterCallback, rawCallback, null);
        Log.i("CAMERA", "Success");
    } catch (Exception e) {
        Log.e("CAMERA", "Click Failure");
        e.printStackTrace();
    }
    // Commented out following line and moved it into your callbacks
    //cam.release();
    return super.onStartCommand(intent, flags, startId);
}