Android 意图 - 从图库中选择图像

Question

我正在关注此sample code 以发送获取图像的意图。

Intent i = new Intent();
i.setAction(Intent.ACTION_GET_CONTENT);

i.setType("image/*");

if (i.resolveActivity(getPackageManager()) != null) {
     startActivityForResult(i, 3);
}

在onActivityResult：

if(requestCode == 3 && resultCode == RESULT_OK) {
     Bitmap thumbnail = data.getParcelableExtra("data");

     if(thumbnail == null) {
        Toast.makeText(getApplicationContext(), "Thumbnail is null", Toast.LENGTH_SHORT).show();
        return;
     }

     ImageView iv = (ImageView) findViewById(R.id.imageView);
     iv.setImageBitmap(thumbnail);
 }

发送意图后，图像选择器启动，我选择图库中的一张图像。但是在onActivityResult中，对应示例代码中的如下语句（我在Android 4.4中改为getParcelableExtra）：

Bitmap thumbnail = data.getParcelable("data");

我得到的缩略图为空。我正在 Genymotion VM 上进行测试。

我做错了什么？

Answer 1

        btnFromGallery.setOnClickListener(new OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        // TODO Auto-generated method stub

                        try {
                            Intent intent = new Intent();
                            intent.setType("image/*");
                            intent.setAction(Intent.ACTION_GET_CONTENT);
                            Log.i("after select", "get image");
                            startActivityForResult(Intent.createChooser(intent, ""), PICK_IMAGE);
                        } catch (Exception e) {
                            Toast.makeText(getApplicationContext(), R.string.imageException, Toast.LENGTH_LONG).show();
                            Log.e(e.getClass().getName(), e.getMessage(), e);
                        }
                    }
                });

    //onActivityResult code:

    @Override
        protected void onActivityResult(int requestCode, int resultCode, Intent data) {
            switch (requestCode) {

            case PICK_IMAGE:
                if (resultCode == Activity.RESULT_OK) {
                    Log.i("On onActivityResult", "on Activity Result");
                    Uri selectedImageUri = data.getData();
                    String filePath = null;

                    try {
                        String filemanagerstring = selectedImageUri.getPath();

                        selectedImagePath = getPath(selectedImageUri);
                        if (selectedImagePath != null) {
                            filePath = selectedImagePath;
                        } else if (filemanagerstring != null) {
                            filePath = filemanagerstring;
                        } else {
                            Toast.makeText(getApplicationContext(), R.string.unknownPath, Toast.LENGTH_LONG).show();
                        }

                        if (filePath != null) {
                            decodeFile(filePath);
                        } else {
                            bitmap = null;
                        }
                    } catch (Exception e) {
                        Toast.makeText(getApplicationContext(), R.string.dataException, Toast.LENGTH_LONG).show();
                    }
                }
                break;

            }
        }


//Get Path Method

    public String getPath(Uri uri) {
            String[] projection = { MediaColumns.DATA };
            Cursor cursor = managedQuery(uri, projection, null, null, null);
            if (cursor != null) {
                int column_index = cursor.getColumnIndexOrThrow(MediaColumns.DATA);
                cursor.moveToFirst();
                return cursor.getString(column_index);
            } else
                return null;
        }

//Decode File method

public void decodeFile(String filePath) {
        try {

            File f = new File(filePath);
            ExifInterface exif = new ExifInterface(f.getPath());
            int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);

            int angle = 0;

            if (orientation == ExifInterface.ORIENTATION_ROTATE_90) {
                angle = 90;
            } else if (orientation == ExifInterface.ORIENTATION_ROTATE_180) {
                angle = 180;
            } else if (orientation == ExifInterface.ORIENTATION_ROTATE_270) {
                angle = 270;
            }

            Matrix mat = new Matrix();
            mat.postRotate(angle);
            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inSampleSize = 2;

            Bitmap bmp = BitmapFactory.decodeStream(new FileInputStream(f), null, options);
            bitmap = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), mat, true);
            ByteArrayOutputStream outstudentstreamOutputStream = new ByteArrayOutputStream();
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, outstudentstreamOutputStream);
            imgEdit.setImageBitmap(bitmap);

Answer 2

你能试试他的答案吗？ How to pick an image from gallery (SD Card) for my app?

使用getData() 而不是getParcelableExtra()

它将返回一个 Uri，您需要使用 ContentResolver 来获取图像。

另外，使用Intent.ACTION_PICK 代替Intent.ACTION_GET_CONTENT。

Answer 3

不是获取位图，而是从数据中获取 URI 并自己加载位图。

           Uri selectedImageUri = data.getData();
           String selectedImagePath = getPath(selectedImageUri);

Answer 4

试试这个.. 对你有帮助

  /**
                     * Images uploaded through gallery
                     * 
                     */

                    btn_gallery.setOnClickListener(new OnClickListener()
                    {

                        @Override
                        public void onClick(View v)
                        {
                            if (v.getId() == R.id.btn_gallery)
                            {
                                upload = true;
                                gallery_upload();


                            }

                        }
                    });



     /**
             * By this method we can upload the image from gallery
             */
            public void gallery_upload()
            {
                Log.d("Upload", "inside gallery upload");
                Intent i = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

                startActivityForResult(i, RESULT_LOAD_IMAGE);

            }

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

            if (upload)
            {
                if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && null != data)
                {
                    Uri selectedImage = data.getData();
                    String[] filePathColumn = { MediaStore.Images.Media.DATA };

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

                    int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
                    picturePath = cursor.getString(columnIndex);
                    Log.e("", "" + picturePath);
                    cursor.close();

                    imageView = (ImageView) findViewById(R.id.upload_register_image);

                    File image = new File(picturePath);
                    if (image.exists())
                    {
                        File f = image.getAbsoluteFile();
                        decodeFile(f);
                    }
                    else
                    {
                        Log.d("VEHICLEREGISTERATION", "image doesnt exist");
                    }

                    upload = false;

                    imagePath(picturePath);

                }
    }
    }
/**
 * Helps to decode size of the image
 * */
private Bitmap decodeFile(File f)
{
    try
    {
        // Decode image size
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(new FileInputStream(f), null, o);

        // The new size we want to scale to
        final int REQUIRED_SIZE = 70;

        // Find the correct scale value. It should be the power of 2.
        int scale = 1;
        while (o.outWidth / scale / 2 >= REQUIRED_SIZE && o.outHeight / scale / 2 >= REQUIRED_SIZE)
            scale *= 2;

        // Decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        Bitmap bit_map = BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
        imageView.setImageBitmap(bit_map);

    }
    catch (FileNotFoundException e)
    {
    }
    return null;
}

public void imagePath(String Path)
{
    finalImgPath = Path;

}