Android BitmapFactory.decodeFile返回null

Question

我调用Activity.requestPermissions（READ_EXTERNAL_STORAGE），并在用户单击允许后尝试使用BitmapFactory.decodeFile（path），但它返回null。当已经授予的权限都可以。怎么了？

ImageChooser类

public class ImageChooser { 

    private final static int GET_IMAGE_REQUEST = 1; 

    private final static int PERMISSIONS_REQUEST = 2; 

    public interface Callback { 
     void onImageChosen(Bitmap image); 
    } 

    private Activity activity; 
    private Fragment fragment; 
    private Callback callback; 

    private String capturedImagePath; 

    public ImageChooser(Activity activity, Fragment fragment, Callback callback) { 
     this.activity = activity; 
     this.fragment = fragment; 
     this.callback = callback; 
    } 

    public void choose() { 
     boolean readStorageGranted = PermissionsManager 
       .isPermissionGrantedReal(activity, Permission.READ_EXTERNAL_STORAGE); 
     boolean cameraGranted = PermissionsManager 
       .isPermissionGrantedReal(activity, Permission.CAMERA); 

     if (readStorageGranted && cameraGranted) { 
      chooseImage(); 
     } else { 
      fragment.requestPermissions(new String[] { 
        Permission.CAMERA.permission, 
        Permission.READ_EXTERNAL_STORAGE.permission 
      }, PERMISSIONS_REQUEST); 
     } 
    } 

    private void chooseImage() { 
     Intent pickIntent = new Intent(Intent.ACTION_PICK); 
     pickIntent.setType("image/*"); 

     String filename = "image.png"; 
     String dir = activity.getExternalCacheDir().getAbsolutePath(); 

     capturedImagePath = dir + "/" + filename; 
     File file = new File(capturedImagePath); 

     Intent captureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); 
     captureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(file)); 

     Intent chooserIntent = Intent.createChooser(pickIntent, 
       activity.getString(R.string.take_choose_photo)); 

     chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, new Intent[] { captureIntent }); 

     fragment.startActivityForResult(chooserIntent, GET_IMAGE_REQUEST); 
    } 

    public void handleOnActivityResult(int requestCode, int resultCode, Intent data) { 
     if (requestCode == GET_IMAGE_REQUEST && resultCode == Activity.RESULT_OK) { 
      Bitmap image = null; 

      String picturePath = null; 

      if (data == null) { // From Camera. 
       File imageFile = new File(capturedImagePath); 
       if (imageFile.exists()) { 
        image = BitmapFactory.decodeFile(imageFile.getAbsolutePath()); 
       } 
      } else { // From Gallery. 
       Uri selectedImage = data.getData(); 

       String[] filePathColumn = { MediaStore.Images.Media.DATA }; 

       Cursor cursor = activity.getContentResolver().query(selectedImage, filePathColumn, 
         null, null, null); 

       if (cursor != null) { 
        cursor.moveToFirst(); 

        int columnIndex = cursor.getColumnIndex(filePathColumn[0]); 
        picturePath = cursor.getString(columnIndex); 
        cursor.close(); 

        image = BitmapFactory.decodeFile(picturePath); 
       } 
      } 

      if (image != null) { 
       callback.onImageChosen(image); 

      } 
     } 
    } 

    public void handleOnRequestPermissionsResult(int requestCode, String[] permissions, 
               int[] grantResults) { 
     if (grantResults.length > 0 && 
       grantResults[0] == PackageManager.PERMISSION_GRANTED && 
       grantResults[1] == PackageManager.PERMISSION_GRANTED) { 

      chooseImage(); 
     } 
    } 
} 

使用

public class CustomizeFragment extends Fragment { 

    @Bind(R.id.add_image) 
    View addImageView; 

    @Bind(R.id.switch_button_off) 
    Button switchOffButton; 

    @Bind(R.id.switch_button_on) 
    Button switchOnButton; 

    @Bind(R.id.mb_image) 
    RoundedImageView imageView; 

    private ImageChooser imageChooser; 

    @Nullable 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View v = inflater.inflate(R.layout.fragment_customize, container, false); 

     ButterKnife.bind(this, v); 

     return v; 
    } 

    @Override 
    public void onActivityCreated(@Nullable Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 

     imageChooser = new ImageChooser(getActivity(), this, image -> { 
      addImageView.setVisibility(View.GONE); 
      imageView.setVisibility(View.VISIBLE); 

      imageView.setImageBitmap(image); 
     }); 
    } 

    @Override 
    public void onDestroyView() { 
     super.onDestroyView(); 

     ButterKnife.unbind(this); 
    } 

    @OnClick({R.id.add_image, R.id.mb_image}) 
    void onAddImageClick() { 
     imageChooser.choose(); 
    } 


    @Override 
    public void onActivityResult(int requestCode, int resultCode, Intent data) { 
     super.onActivityResult(requestCode, resultCode, data); 

     imageChooser.handleOnActivityResult(requestCode, resultCode, data); 
    } 

    @Override 
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { 
     super.onRequestPermissionsResult(requestCode, permissions, grantResults); 

     imageChooser.handleOnRequestPermissionsResult(requestCode, permissions, grantResults); 
    } 
} 

Answer 1

晴BitmapFactory.decodeFile（）返回null的实例是.JPG图像具有这样的分辨率作出了位图用于它需要比操作系统可以提供更多的内存。尝试缩小它。