保存图像文件太慢，无法立即在 Imageview 中显示

Question

在我的应用程序中，我保存了一个图像文件（从照相手机拍摄的照片），但如果我想立即在 Imageview 中显示其缩略图，有时会出现错误。为什么？保存过程是否太慢？我可以使用替代方法来保存我的图像文件吗？

我在这里调用我的相机：

        camera.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            if (intent.resolveActivity(getActivity().getPackageManager()) != null) {
                // Create the File where the photo should go
                File photoFile = null;
                try {
                    photoFile = createImageFile();
                } catch (IOException ex) {
                    // Error occurred while creating the File
                    Log.v("Crea file Immagine", "IOException");
                }
                // Continue only if the File was successfully created
                if (photoFile != null) {
                    Log.v("photofile",String.valueOf(photoFile));
                    Uri mSelectedImageUri= Uri.fromFile(photoFile);
                    Log.v("mSelectedImageUri", String.valueOf(mSelectedImageUri));
                    intent.putExtra(MediaStore.EXTRA_OUTPUT, mSelectedImageUri);
                    startActivityForResult(intent, CAMERA_REQUEST);
                }
            }
        }
    });

我在这里保存我的图像文件：

    private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    sharedPreference.save(context,"nomeFile",timeStamp);

    File storageDir = new File(Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_DCIM) + File.separator + "BottiglieDiVino");
    boolean success;
    if (!storageDir.exists()) {
        success = storageDir.mkdir();
        if (success) {
            // Do something on success
            Log.v("Crea /BottiglieDiVino", "Ho Creato nuova directory");
        } else {
            // Do something else on failure
            Log.v("Crea /BottiglieDiVino", "ERRORE nel creare nuova directory");
        }
    }

    File image = new File(storageDir, timeStamp + ".jpg");
    // Save a file: path for use with ACTION_VIEW intents
    percorso = image.getAbsolutePath();
    sharedPreference.save(context,"percorso", percorso);
    Log.v("percorso", percorso);
    return image;
}

在这里我得到了这个错误

java.io.FileNotFoundException: /: open failed: EISDIR (Is a directory)
libcore.io.IoBridge.open(IoBridge.java:409)
java.io.FileInputStream.<init>(FileInputStream.java:78)
java.io.FileInputStream.<init>(FileInputStream.java:105)
android.content.ContentResolver.openInputStream(ContentResolver.java:630) 

com.example.android.swipetabs.FragmentTab2.decodeSampledBitmapFromUri(FragmentTab2.java:

附言在最后一行:) 是错误。

    @Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == CAMERA_REQUEST && resultCode == Activity.RESULT_OK) {

        percorso = sharedPreference.getValue(context, "percorso");

        sharedPreference.save(context,"check23", "ok");
        Log.v("percorso", percorso);
        foto.setImageBitmap(display(percorso));

    }
}

    public Bitmap decodeSampledBitmapFromUri(Uri uri, int reqWidth, int reqHeight) {

    try {
        // First decode with inJustDecodeBounds=true to check dimensions
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;

        BitmapFactory.decodeStream(getActivity().getContentResolver().openInputStream(uri), null, options);

请帮帮我。

Answer 1

注意：为 marashmallow 或更高版本提供这些权限运行时间，并在您的其他设备上获得权限时放置您的代码，它可以正常工作

在主祭中

 <uses-permission android:name="android.permission.CAMERA" />
 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

运行时

 public static final int REQUEST_ID_MULTIPLE_PERMISSIONS = 10;

camera.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        permissions= new String[]{
                    Manifest.permission.CAMERA,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE};


            if (checkPermissions())
            {
                Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                if (intent.resolveActivity(demo.this.getPackageManager()) != null) {
                    // Create the File where the photo should go
                    File photoFile = null;
                    try {
                        photoFile = createImageFile();
                    } catch (IOException ex) {
                        // Error occurred while creating the File
                        Log.v("Crea file Immagine", "IOException");
                    }
                    // Continue only if the File was successfully created
                    if (photoFile != null) {
                        Log.v("photofile",String.valueOf(photoFile));
                        Uri mSelectedImageUri= Uri.fromFile(photoFile);
                        Log.v("mSelectedImageUri", String.valueOf(mSelectedImageUri));
                        intent.putExtra(MediaStore.EXTRA_OUTPUT, mSelectedImageUri);
                        startActivityForResult(intent, CAMERA_REQUEST);
                    }
                }



            }


        }

    });

 private  boolean checkPermissions() {
    int result;
    List<String> listPermissionsNeeded = new ArrayList<>();
    for (String p:permissions) {
        result = ContextCompat.checkSelfPermission(this,p);
        if (result != PackageManager.PERMISSION_GRANTED) {
            listPermissionsNeeded.add(p);
        }
    }
    if (!listPermissionsNeeded.isEmpty()) {
        ActivityCompat.requestPermissions(this, listPermissionsNeeded.toArray(new String[listPermissionsNeeded.size()]),REQUEST_ID_MULTIPLE_PERMISSIONS);
        return false;
    }
    return true;
}