android - 处理多个大位图时内存不足

Question

在我正在开发的应用程序中，部分用户输入是一系列图像。其中一些原始格式可能有 4MB 大。我调整它们的大小并旋转它们，然后将它们保存在设备内存的应用程序部分以供以后使用。我遇到的问题是，即使我在保存每个位图后对其进行回收，我似乎也用完了内存。

主要处理如下

private class SaveImagesTask extends AsyncTask<Long, Void, Void>{
    @Override
    protected Void doInBackground(Long... ids){
        long id = ids[0];
        Iterator<ImageButton> itImg = arrBtnImage.iterator();
        Iterator<TextView> itLbl = arrLblImage.iterator();
        while(itImg.hasNext() && itLbl.hasNext()){
            String imgPath = (String) itImg.next().getTag();
            String imgLbl = itLbl.next().getText().toString().trim();
            String imgName = imgLbl.replace(" ", "_").replace(",", "_");
            imgName += ".jpg";

            if(imgPath != null){
                /* Save resized version of image */
                File dir = getApplicationContext().getFilesDir();
                dir = new File(dir, "temp/" + Long.toString(plantId));
                boolean madeDir = dir.mkdirs();
                File path = new File(dir, imgName);
                Bitmap toSave = getScaledBitmap(imgPath, IMAGE_MAX_SIDE_LENGTH, IMAGE_MAX_SIDE_LENGTH);

                try{
                    BufferedOutputStream outStream = new BufferedOutputStream(new FileOutputStream(path));
                    boolean insertSuccess = toSave.compress(Bitmap.CompressFormat.JPEG, 90, outStream);
                    outStream.close();
                }
                catch(FileNotFoundException e){
                    e.printStackTrace();
                }
                catch(IOException e){
                    e.printStackTrace();
                }
                toSave.recycle();
            }//if
        }//while(more images to process)
    }// method: doInBackground(params)
}// inner class: saveImages extends AsyncTask

这里是我调整图片大小的地方

private Bitmap getScaledBitmap(String picturePath, int newWidth, int newHeight){
    /* Size */
    BitmapFactory.Options sizeOptions = new BitmapFactory.Options();
    sizeOptions.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(picturePath, sizeOptions);
    int sampleSize = 1;
    int rawHeight = sizeOptions.outHeight;
    int rawWidth = sizeOptions.outWidth;
    if(rawHeight > newHeight || rawWidth > newWidth){
        /* Find the dimension that needs to change the most */
        int heightRatio = Math.round((float) rawHeight / (float) newHeight);
        int widthRatio = Math.round((float) rawWidth / (float) newWidth);

        sampleSize = (heightRatio > widthRatio ? heightRatio : widthRatio);
    }//if(raw image is wider or taller than it should be){reduce size so neither is too large}

    sizeOptions.inJustDecodeBounds = false;//Load pixels for display.
    sizeOptions.inSampleSize = sampleSize;//Set shrink factor.
    Bitmap scaledBitmap = BitmapFactory.decodeFile(picturePath, sizeOptions);

    /* Rotation */
    int rotation = 1;
    try{
        ExifInterface exif = new ExifInterface(picturePath);
        rotation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
    }
    catch(IOException e){
        e.printStackTrace();
    }
    int rotationInDegrees = 0;
    if(rotation == ExifInterface.ORIENTATION_ROTATE_90)
        rotationInDegrees = 90;
    else if(rotation == ExifInterface.ORIENTATION_ROTATE_180)
        rotationInDegrees = 180;
    else if(rotation == ExifInterface.ORIENTATION_ROTATE_270)
        rotationInDegrees = 270;

    Matrix matrix = new Matrix();
    if(rotation != 0f)
        matrix.preRotate(rotationInDegrees);

    return Bitmap.createBitmap(scaledBitmap, 0, 0, 
                scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
}// method: getScaledBitmap(String, int, int)

在我开始收到关于这个问题如此普遍的评论之前，我会指出我没有显示这些图像，所以我并不是要将所有这些都保存在内存中。我需要保留大图像，因为用户希望能够放大图片，但我正在调整它们的大小，因为它们不需要大得离谱。我在 SO 上看到的关于图像和 OOM 错误的几乎所有其他解决方案都不适用于我对多个图像的背靠背访问。

所以就像我说的，我正在回收每个保存后的位图，但它们似乎仍在使用内存。知道我错过了什么吗？

Answer 1

您没有在 getScaledBitmap 中回收 scaledBitmap。解决这个问题应该有所帮助。更改此行:

return Bitmap.createBitmap(scaledBitmap, 0, 0, 
            scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);

类似于:

Bitmap newBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0, 
            scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
scaledBitmap.recycle();
return newBitmap;