MediaStore.Images.Thumbnails.getThumbnail返回错误的缩略图而不是NULL

Question

考虑如下图所示的场景:

三张照片,其中一张是大型GIF文件(3MP).

我正在查询MediaStore以检索相应的缩略图.如果我使用此sortOrder通过CursorLoader初始化Cursor:

MediaStore.Images.Media.DATE_ADDED + " DESC""

会发生什么: MediaStore返回先前成功检索的缩略图:

预期的行为:当MediaStore由于某种原因无法检索给定图像的缩略图时,它必须返回NULL,根据其Javadoc:"...返回一个Bitmap实例.如果与origId关联的原始图像不是,则它可以为null存在或记忆不够."

如果我用这个sortOrder初始化Cursor:

MediaStore.Images.Media.DATE_ADDED + " ASC""

它运行得很好:

但是我不能简单地改变sortOrder,因为要求是先显示最新的图片.

下面是我的示例代码,这里是完整的示例项目以及用于重现的三个图像.

package com.example.getimagefrommediastore;

import android.app.Activity;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.provider.MediaStore;
import android.support.v4.content.CursorLoader;
import android.widget.ImageView;
import android.widget.TextView;

public class GetThumbnailsFromMediaStoreSampleActivity extends Activity {

TextView mThumb_id_01;
TextView mThumb_id_02;
TextView mThumb_id_03;
ImageView mImg_01;
ImageView mImg_02;
ImageView mImg_03;
boolean isThumb01 = true; // Simple flag to control this example
boolean isThumb02 = true;
Cursor mCursorLoader;
int mColumnIndex;
long mOrigId; // Original image id associated with thumbnail of interest

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // Just initializing views
    mThumb_id_01 = (TextView) findViewById(R.id.thumb_id_01);
    mThumb_id_02 = (TextView) findViewById(R.id.thumb_id_02);
    mThumb_id_03 = (TextView) findViewById(R.id.thumb_id_03);
    mImg_01 = (ImageView) findViewById(R.id.thumb_01);
    mImg_02 = (ImageView) findViewById(R.id.thumb_02);
    mImg_03 = (ImageView) findViewById(R.id.thumb_03);

    // Initializing CursorLoader
    mCursorLoader = initializeCursorLoader();
    mColumnIndex = mCursorLoader.getColumnIndex(MediaStore.Images.Media._ID);

    // Go thru all the images in the device (EXTERNAL_CONTENT_URI)
    // In this example there are only three images
    for (int i = 0; i < mCursorLoader.getCount(); i++) {
        mCursorLoader.moveToPosition(i);
        mOrigId = mCursorLoader.getInt(mColumnIndex);

        // Update views
        chooseViewToUpdate();
    }
}

private Cursor initializeCursorLoader() {
    String[] COLUMNS = {
            MediaStore.Images.Thumbnails._ID, MediaStore.Images.Media.DATA
    };

    CursorLoader cursorLoader = new CursorLoader(
    GetThumbnailsFromMediaStoreSampleActivity.this, // Context
    MediaStore.Images.Media.EXTERNAL_CONTENT_URI, // Uri
    COLUMNS, // Projection
    null, // Selection
    null, // Selection Args

    // Sort Order: DESC = newest first
    // Sort Order: ASC = oldest first

    MediaStore.Images.Media.DATE_ADDED + " DESC");

    // *** NOTE ***
    // With:
    //
    // MediaStore.Images.Media.DATE_ADDED + " ASC"
    //
    // It runs just fine (MediaStore returns 'null' for invalid thumbnails)
    // The problem seems to reside on the " DESC" tag.
    //
    // How bizarre is that?

    return cursorLoader.loadInBackground();
}

private void chooseViewToUpdate() {
    if (isThumb01) {
        updateUI(mThumb_id_01, mImg_01);
        isThumb01 = false;
    } else if (isThumb02) {
        updateUI(mThumb_id_02, mImg_02);
        isThumb02 = false;
    } else {
        updateUI(mThumb_id_03, mImg_03);
    }
}

private void updateUI(TextView textView, ImageView imgView) {
    textView.setText("ID:" + String.valueOf(mOrigId));

    Bitmap mediaStoreThumbmail = MediaStore.Images.Thumbnails.getThumbnail(
            this.getContentResolver(),
            mOrigId,
            MediaStore.Images.Thumbnails.MICRO_KIND, null);

    if (mediaStoreThumbmail != null) {
        imgView.setImageBitmap(mediaStoreThumbmail);
    }
}

我错过了什么吗？有谁知道可能有什么问题？

无论如何,我填补了一个针对Android的错误.

编辑

似乎这个问题在Lollipop中已得到修复.(该线程的最后评论).

Answer 1

三年后，这个问题似乎在 Lollipop 中得到了解决。（该线程的最后评论）。
因此我正在回答我自己的问题。