如何从Uri中获得位图对象(如果我成功地将它存储在 /data/data/MYFOLDER/myimage.png或文件///data/data/MYFOLDER/myimage.png)在我的应用程序中使用它?

有人知道怎么做到吗?


当前回答

(芬兰湾的科特林) 所以,截至2020年4月7日,上述选项都没用,但以下是对我有效的:

如果你想在val中存储位图,并设置一个imageView,使用这个: val bitmap = BitmapFactory.decodeFile(currentPhotoPath).also {bitmap -> imageView.setImageBitmap(bitmap)} 如果你只是想设置位图为和imageView,使用这个: BitmapFactory.decodeFile(currentPhotoPath).also {bitmap -> imageView.setImageBitmap(bitmap)}

其他回答

private fun setImage(view: ImageView, uri: Uri) {
        val stream = contentResolver.openInputStream(uri)
        val bitmap = BitmapFactory.decodeStream(stream)
        view.setImageBitmap(bitmap)
}

下面是正确的做法:

protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
    super.onActivityResult(requestCode, resultCode, data);
    if (resultCode == RESULT_OK)
    {
        Uri imageUri = data.getData();
        Bitmap bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), imageUri);
    }
}

如果你需要加载非常大的图像,下面的代码将以tile的形式加载它(避免大的内存分配):

BitmapRegionDecoder decoder = BitmapRegionDecoder.newInstance(myStream, false);  
Bitmap region = decoder.decodeRegion(new Rect(10, 10, 50, 50), null);

点击这里查看答案

下面是正确的方法,同时也要注意内存的使用情况:

protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
  super.onActivityResult(requestCode, resultCode, data);
  if (resultCode == RESULT_OK)
  {
    Uri imageUri = data.getData();
    Bitmap bitmap = getThumbnail(imageUri);
  }
}

public static Bitmap getThumbnail(Uri uri) throws FileNotFoundException, IOException{
  InputStream input = this.getContentResolver().openInputStream(uri);

  BitmapFactory.Options onlyBoundsOptions = new BitmapFactory.Options();
  onlyBoundsOptions.inJustDecodeBounds = true;
  onlyBoundsOptions.inDither=true;//optional
  onlyBoundsOptions.inPreferredConfig=Bitmap.Config.ARGB_8888;//optional
  BitmapFactory.decodeStream(input, null, onlyBoundsOptions);
  input.close();

  if ((onlyBoundsOptions.outWidth == -1) || (onlyBoundsOptions.outHeight == -1)) {
    return null;
  }

  int originalSize = (onlyBoundsOptions.outHeight > onlyBoundsOptions.outWidth) ? onlyBoundsOptions.outHeight : onlyBoundsOptions.outWidth;

  double ratio = (originalSize > THUMBNAIL_SIZE) ? (originalSize / THUMBNAIL_SIZE) : 1.0;

  BitmapFactory.Options bitmapOptions = new BitmapFactory.Options();
  bitmapOptions.inSampleSize = getPowerOfTwoForSampleRatio(ratio);
  bitmapOptions.inDither = true; //optional
  bitmapOptions.inPreferredConfig=Bitmap.Config.ARGB_8888;//
  input = this.getContentResolver().openInputStream(uri);
  Bitmap bitmap = BitmapFactory.decodeStream(input, null, bitmapOptions);
  input.close();
  return bitmap;
}

private static int getPowerOfTwoForSampleRatio(double ratio){
  int k = Integer.highestOneBit((int)Math.floor(ratio));
  if(k==0) return 1;
  else return k;
}

Mark Ingram的文章中的getBitmap()调用也调用decodeStream(),因此不会丢失任何功能。

引用:

Android:在SD卡上获取图像的缩略图,给定原始图像的Uri 处理大位图

现在我在Kotlin中使用下面的方法

PICK_IMAGE_REQUEST ->
    data?.data?.let {
        val bitmap = BitmapFactory.decodeStream(contentResolver.openInputStream(it))
        imageView.setImageBitmap(bitmap)
    }

使用startActivityForResult方法,如下所示

        startActivityForResult(new Intent(Intent.ACTION_PICK).setType("image/*"), PICK_IMAGE);

你可以得到这样的结果:

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (resultCode != RESULT_OK) {
        return;
    }
    switch (requestCode) {
        case PICK_IMAGE:
            Uri imageUri = data.getData();
            try {
                Bitmap bitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), imageUri);
            } catch (IOException e) {
                e.printStackTrace();
            }
         break;
    }
}