建立Camera App，它无法拍照。返回“ D / [应用程序名称]：创建目录失败”

Question

我目前正在开发可以拍照的应用程序。我主要将其用作教程：https://developer.android.com/guide/topics/media/camera#capture-picture 应当指出，我不打算让它录制视频。

无论如何，每次我单击按钮拍照时，都会有些滞后，并且什么也没有发生。 Logcat会显示“ D / [应用程序名称]：创建目录失败”。是的，我确实搜索过该词，但是找不到真正对我有帮助的解决方案。

最奇怪的部分是，如果我再次单击捕获按钮，应用程序将崩溃并显示以下消息：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.assessment, PID: 13633
    java.lang.RuntimeException: takePicture failed
        at android.hardware.Camera.native_takePicture(Native Method)
        at android.hardware.Camera.takePicture(Camera.java:1551)
        at android.hardware.Camera.takePicture(Camera.java:1493)
        at com.example.assessment.MainActivity.onClick(MainActivity.java:113)
...

我将在下面的代码中标记第113行。

我希望解决方案是我忽略的简单事物。

我认为可能是导致问题的原因之一，但是我不确定方法的作用。我将在这些区域标记很多星号。

正如我所说，我曾尝试寻找解决方案，但据我所知，一切都是正确的。

主要活动：

package com.example.assessment;
//Imports are here

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    private Camera camera;
    private CameraPreview preview;

    public static final int MEDIA_TYPE_IMAGE = 1;

    //Skipped this code, it just declared buttons

    PictureCallback picture = new PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {

            File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
            if (pictureFile == null){
                   //Put error message here
                return;
            }

            try {
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
            } catch (FileNotFoundException e) {
                Log.d("Assessment", "File not Found");
            } catch (IOException e) {
                Log.d("Assessment", "Cannot access file");
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE); //These two lines hides the notification bar at the top of the screen
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_main);

        //Skipped code here, it just sets up the buttons

        //The following takes the user to a new activity if they lack permissions - I check for permissions for the camera, read externally, and write externally. Yes, I made sure they were all enabled when testing the app.
        if (!(PermissionsActivity.hasAllPermissions())) {
            Intent goToPermissionsIntent = new Intent(MainActivity.this, PermissionsActivity.class);
            startActivity(goToPermissionsIntent);
        }

        if(hasCamera(this)){
            camera = getCameraInstance();
            preview = new CameraPreview(this, camera);
            FrameLayout fl_preview = (FrameLayout)findViewById(R.id.flo_cameraPreview);
            fl_preview.addView(preview);
        }
    }

    /// Check if this device has a camera - from API
    private boolean hasCamera(Context context) {
        if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
            return true;
        } else {
            return false;
        }
    }

    // Gets an instance of the Camera object - from API
    public static Camera getCameraInstance(){
        Camera c = null;
        try {
            c = Camera.open(); // attempt to get a Camera instance
        }
        catch (Exception e){
            //Do something here
        }
        return c;
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_capture:
                //captures photo
//The line below is line 113
                camera.takePicture(null, null, picture);
                break;
            //I had two other switch cases here but they are irreverent for now - they just took you to other activities.
        }
    }

    //I took this from the API, it is never called though
    private static Uri getOutputMediaFileUri(int type){
        return Uri.fromFile(getOutputMediaFile(type));
    }

    /** Create a File for saving an image */
    private static File getOutputMediaFile(int type){

        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES), "Assessment");

//******* Below is where the log notification above is referenced.  I am not sure what to do.
        // Create the storage directory if it does not exist
        if (! mediaStorageDir.exists()){
            if (! mediaStorageDir.mkdirs()){
                Log.d("Assessment", "failed to create directory");
                return null;
            }
        }

        // Create a media file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile;
        if (type == MEDIA_TYPE_IMAGE){
            mediaFile = new File(mediaStorageDir.getPath() + File.separator + "IMG_"+ timeStamp + ".jpg");
        } else {
            return null;
        }
        return mediaFile;
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (camera != null){
            camera.release();        // release the camera for other applications
            camera = null;
        }
    }
}