Android应用从图库中选择不显示的照片

Question

我正在创建一个Android应用程序，我有一个按钮，当用户点击它时会弹出一个弹出窗口，询问用户是否要拍照，从库中选择或取消。当用户拍摄新照片时，它会将活动中的占位符图像替换为刚刚拍摄的图像。每当用户尝试从库中进行选择时，图像都不会显示，并且占位符图像正在消失。下面是处理单击照片按钮的代码部分，下面是分配给按钮和图像的属性。

/** Called when the user clicks the photo button */
private void selectImage() {
    final CharSequence[] items = { "Take Photo", "Choose from Library",
            "Cancel" };

    AlertDialog.Builder builder = new AlertDialog.Builder(NewDogActivity.this);
    builder.setTitle("Add Photo!");
    builder.setItems(items, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int item) {
            if (items[item].equals("Take Photo")) {
                Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                startActivityForResult(intent, REQUEST_CAMERA);
            } else if (items[item].equals("Choose from Library")) {
                Intent intent = new Intent(
                        Intent.ACTION_PICK,
                        android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
                intent.setType("image/*");
                startActivityForResult(
                        Intent.createChooser(intent, "Select File"),
                        SELECT_FILE);
            } else if (items[item].equals("Cancel")) {
                dialog.dismiss();
            }
        }
    });
    builder.show();
}

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

    if (resultCode == Activity.RESULT_OK) {
        if (requestCode == SELECT_FILE)
            onSelectFromGalleryResult(data);
        else if (requestCode == REQUEST_CAMERA)
            onCaptureImageResult(data);
    }
}


private void onCaptureImageResult(Intent data) {
    Bitmap thumbnail = (Bitmap) data.getExtras().get("data");
    ByteArrayOutputStream bytes = new ByteArrayOutputStream();
    thumbnail.compress(Bitmap.CompressFormat.JPEG, 90, bytes);

    File destination = new File(Environment.getExternalStorageDirectory(),
            System.currentTimeMillis() + ".jpg");

    FileOutputStream fo;
    try {
        destination.createNewFile();
        fo = new FileOutputStream(destination);
        fo.write(bytes.toByteArray());
        fo.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    ivImage.setImageBitmap(thumbnail);
}

@SuppressWarnings("deprecation")
private void onSelectFromGalleryResult(Intent data) {
    Uri selectedImageUri = data.getData();
    String[] projection = { MediaStore.MediaColumns.DATA };
    Cursor cursor = managedQuery(selectedImageUri, projection, null, null,
            null);
    int column_index = cursor.getColumnIndexOrThrow(MediaStore.MediaColumns.DATA);
    cursor.moveToFirst();

    String selectedImagePath = cursor.getString(column_index);

    Bitmap bm;
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(selectedImagePath, options);
    final int REQUIRED_SIZE = 200;
    int scale = 1;
    while (options.outWidth / scale / 2 >= REQUIRED_SIZE
            && options.outHeight / scale / 2 >= REQUIRED_SIZE)
        scale *= 2;
    options.inSampleSize = scale;
    options.inJustDecodeBounds = false;
    bm = BitmapFactory.decodeFile(selectedImagePath, options);

    ivImage.setImageBitmap(bm);

这是按钮和图像的属性。

<Button
    style="?android:attr/buttonStyleSmall"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Select Photo"
    android:id="@+id/selectImgButton"
    android:layout_alignBottom="@+id/ImageText"
    android:layout_alignStart="@+id/BreededitText"
    android:layout_alignEnd="@+id/BreededitText"
    android:clickable="true"
    android:background="#2c7134"
    android:enabled="true"
    android:focusable="true"
    android:textColor="#f3ca83"
    android:onClick="choosePicture"/>

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/ivImage"
    android:layout_below="@+id/ImageText"
    android:src="@drawable/ddlogo"
    android:layout_above="@+id/NewSubmitButton"
    android:layout_alignStart="@+id/selectImgButton"
    android:layout_alignEnd="@+id/selectImgButton" />