Android 相机拍照函数不调用回调函数

Question

我正在为我的应用程序处理自定义相机活动。我在这里按照Android开发人员网站上的说明进行操作：http://developer.android.com/guide/topics/media/camera.html一切似乎都很好，除了不调用回调函数并且没有保存图片。这是我的代码：

public class CameraActivity extends Activity {
private Camera mCamera;
private CameraPreview mPreview;
private static final String TAG = "CameraActivity";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.camera);
    // Create an instance of Camera
    mCamera = getCameraInstance();
    // Create our Preview view and set it as the content of our activity.
    mPreview = new CameraPreview(this, mCamera);
    FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
    preview.addView(mPreview);
    Button captureButton = (Button) findViewById(R.id.button_capture);
    captureButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            Log.v(TAG, "will now take picture");
            mCamera.takePicture(null, null, mPicture);
            Log.v(TAG, "will now release camera");
            mCamera.release();
            Log.v(TAG, "will now call finish()");
            finish();
        }
    });        
}
private PictureCallback mPicture = new PictureCallback() {
    @Override
    public void onPictureTaken(byte[] data, Camera camera) {
        Log.v(TAG, "Getting output media file");
        File pictureFile = getOutputMediaFile();
        if (pictureFile == null) {
            Log.v(TAG, "Error creating output file");
            return;
        }
        try {
            FileOutputStream fos = new FileOutputStream(pictureFile);
            fos.write(data);
            fos.close();
        } catch (FileNotFoundException e) {
            Log.v(TAG, e.getMessage());
        } catch (IOException e) {
            Log.v(TAG, e.getMessage());
        }
    }
};
private static File getOutputMediaFile() {
    String state = Environment.getExternalStorageState();
    if (!state.equals(Environment.MEDIA_MOUNTED)) {
        return null;
    }
    else {
        File folder_gui = new File(Environment.getExternalStorageDirectory() + File.separator + "GUI");
        if (!folder_gui.exists()) {
            Log.v(TAG, "Creating folder: " + folder_gui.getAbsolutePath());
            folder_gui.mkdirs();
        }
        File outFile = new File(folder_gui, "temp.jpg");
        Log.v(TAG, "Returnng file: " + outFile.getAbsolutePath());
        return outFile;
    }
}

单击按钮后，我得到日志："现在将拍照"，"现在将释放相机"和"现在将呼叫完成"。活动成功完成，但在

mCamera.takePicture(null, null, mPicture);

函数（没有来自 mPicture 回调或 getMediaOutputFile 函数的日志），并且指定的位置中没有文件。

有什么想法吗？:)非常感谢！

Answer 1

对mCamera.takePicture()的调用是异步的。这意味着调用会立即完成，但实际的拍照和处理会在稍后的某个时间进行。但是，您在从呼叫返回后立即执行此操作 mCamera.takePicture()：

Log.v(TAG, "will now release camera");
mCamera.release();
Log.v(TAG, "will now call finish()");
finish();

这意味着您已经释放了相机资源并完成了活动，然后相机才有机会实际拍照并给您回电。

您需要将该代码移动到回调方法onPictureTaken()中，以便在回调发生后释放资源并完成 Activity。

Answer 2

这样做是为了使用 SurfaceView 自定义相机单击拍摄多个图像

clickbtn.setOnClickListener(new OnClickListener() {
        @SuppressWarnings("deprecation")
        @Override
        public void onClick(View v) {
            for (int i = 0; i < 5; i++) {
                mcamera = mPreview.getCamera();
                getimage(mcamera);
                Toast.makeText(getApplicationContext(),
                        "multiple image count=" + i, 1000).show();
            }
            if (mPreview == null) {
                mPreview = new CamLayer(MainActivity.this);
            }

        }
    });

和

    public static void getimage(Camera mcamera) {

    PictureCallback mPicture = new PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            pictureFile = getOutputMediaFile();
            Log.e("path file 11111111", ""+pictureFile);
            if (pictureFile == null) {
                return;
            }
            try {
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
            } catch (FileNotFoundException e) {
            } catch (Exception e) {
            }
        }
    };
    try {
        mcamera.startPreview();
        mcamera.takePicture(null, null, mPicture);
        Thread.sleep(2000);
    } catch (Exception exception) {
        exception.printStackTrace();
    }
}
private static File getOutputMediaFile() {
    File mediaStorageDir = new File(
            Environment
                    .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
            "Sunil3");
    if (!mediaStorageDir.exists()) {
        if (!mediaStorageDir.mkdirs()) {
            return null;
        }
    }

    File mediaFile = new File(String.format(mediaStorageDir+File.separator+"%d.jpg", System.currentTimeMillis()));
    return mediaFile;
}