将图片添加到媒体库 - Android

Question

我正在尝试向画廊添加一张新图像。我通过意图选择了一张已经存在的图片，然后对其进行了缩放和压缩。

接着，我将处理后得到的位图存储起来：

public static File compressAndSaveImage(Context ctx, Uri imageUri) throws FileNotFoundException {
    File file = null;

    if (imageUri != null) {
        ContextWrapper cw = new ContextWrapper(ctx);
        File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
        file = new File(directory, imageUri.getLastPathSegment());
        System.out.println("storing to " + file);

        InputStream input = ctx.getContentResolver().openInputStream(imageUri);
        Bitmap b = ImageManager.resize(BitmapFactory.decodeStream(input),
                ctx.getResources().getDimension(R.dimen.player_thumb_w),
                ctx.getResources().getDimension(R.dimen.player_thumb_h));

        FileOutputStream fos = new FileOutputStream(file);
        if (b.compress(Bitmap.CompressFormat.PNG, 100, fos)) {
            System.out.println("Compression success");// bmp is your Bitmap instance
        }
        addPictureToGallery(ctx, file);
    }
    return file;
}

但是当我尝试将图片添加到画廊时，没有出现任何错误，但图片也未被添加。我已经尝试了以下两种方法：

private static void addPictureToGallery(Context ctx, File filepath) {
//        Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
//        System.out.println("Publish: " + filepath.exists());
//        System.out.println("Publish: " + filepath.getAbsolutePath());
//        Uri contentUri = Uri.fromFile(filepath);
//        mediaScanIntent.setData(contentUri);
//        ctx.sendBroadcast(mediaScanIntent);
    MediaScannerConnection.scanFile(
            ctx,
            new String[]{filepath.getAbsolutePath()},
            null,
            new MediaScannerConnection.OnScanCompletedListener() {
                @Override
                public void onScanCompleted(String path, Uri uri) {
                    Log.w("mydebug", "file " + path + " was scanned successfully: " + uri);
                }
            });
    }
}

回调函数打印以下行：

file /data/data/test.myapps.appname/app_imageDir/6045564126748266738 was scanned successfully: content://media/external/file/7838

我错过了什么？

- parakmiakos

---

如果图像存储在目录中，例如 getExternalFilesDir，会怎样呢？ - iCantC

Answer 1

感谢 @zgc7009，你给了我正确的方向。我使用了你的一些代码，这是最终结果，供其他想解决这个问题的人参考。

问题确实是我将图像存储在应用的本地存储中。

File storedImagePath = generateImagePath("player", "png");
if (!compressAndSaveImage(storedImagePath, bitmap)) {
    return null;
}
Uri url = addImageToGallery(context.getContentResolver(), "png", storedImagePath);

三种方法的使用如下：

生成路径

private static File getImagesDirectory() {
    File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES) + File.separator + IMAGE_DIR);//Environment.getExternalStorageDirectory()
    if (!file.mkdirs() && !file.isDirectory()) {
        Log.e("mkdir", "Directory not created");
    }
    return file;
}

public static File generateImagePath(String title, String imgType) {
    SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy-hh-mm-ss");
    return new File(getImagesDirectory(), title + "_" + sdf.format(new Date()) + "." + imgType);
}

压缩并保存

public boolean compressAndSaveImage(File file, Bitmap bitmap) {
    boolean result = false;
    try {
        FileOutputStream fos = new FileOutputStream(file);
        if (result = bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos)) {
            Log.w("image manager", "Compression success");
        }
        fos.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return result;
}

添加到画廊

public Uri addImageToGallery(ContentResolver cr, String imgType, File filepath) {
    ContentValues values = new ContentValues();
    values.put(MediaStore.Images.Media.TITLE, "player");
    values.put(MediaStore.Images.Media.DISPLAY_NAME, "player");
    values.put(MediaStore.Images.Media.DESCRIPTION, "");
    values.put(MediaStore.Images.Media.MIME_TYPE, "image/" + imgType);
    values.put(MediaStore.Images.Media.DATE_ADDED, System.currentTimeMillis());
    values.put(MediaStore.Images.Media.DATE_TAKEN, System.currentTimeMillis());
    values.put(MediaStore.Images.Media.DATA, filepath.toString());
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
        values.put(MediaStore.MediaColumns.RELATIVE_PATH, Environment.DIRECTORY_PICTURES + "/YourAppFolder");
        values.put(MediaStore.MediaColumns.IS_PENDING, 1);
        Uri uri = cr.insert(MediaStore.Images.Media.getContentUri(MediaStore.VOLUME_EXTERNAL), values);
        values.clear();
        values.put(MediaStore.Images.Media.IS_PENDING, 0);
        cr.update(uri, values, null, null);
        return uri;
    } else {
        return cr.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
    }
}

- parakmiakos

Answer 2

我会把这个作为一条评论，因为我没有时间详细解释，但是它明显太长了。尝试像这样做（我用这个将位图存储到图库中）。注意，您似乎只是在扫描图像。目前，您似乎正在将文件存储到内部存储而不是手机内容（图库）。

假设我们从ActivityA.class运行此代码，该类扩展自Activity

 /**
 * Will save our card (currently set as a bitmap) as a jpeg and save it into our devices
 * native photo gallery. Unfortunately, the default method for this will add the image to the bottom
 * of the gallery by default, that is no good. This more complex method that utilizes Android's
 * native methods will allow us to store the bitmap at the top of the gallery by setting it's
 * meta data to today's date.
 */
public class SaveBitmapToDevice extends AsyncTask<Bitmap, Void, String>{

    private final ShareType type;

    public SaveBitmapToDevice(ShareType type){
        this.type = type;
    }

    @Override
    protected String doInBackground(Bitmap... cards) {
        return insertImageIntoGallery(getContentResolver(), cards[0], getString(R.string.card_gallery_title),
                getString(R.string.card_gallery_label));
    }

    /**
     * A copy of the Android internals insertImage method, this method populates the
     * meta data with DATE_ADDED and DATE_TAKEN. This fixes a common problem where media
     * that is inserted manually gets saved at the end of the gallery (because date is not populated).
     * @see android.provider.MediaStore.Images.Media#insertImage(android.content.ContentResolver, Bitmap, String, String).
     * If the MediaStore not available, we will redirect the file to our alternative source, the SD card.
     */
    public String insertImageIntoGallery(ContentResolver cr, Bitmap source, String title, String description) {

        ContentValues values = new ContentValues();
        values.put(MediaStore.Images.Media.TITLE, title);
        values.put(MediaStore.Images.Media.DISPLAY_NAME, title);
        values.put(MediaStore.Images.Media.DESCRIPTION, description);
        values.put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg");
        // Add the date meta data to ensure the image is added at the front of the gallery
        values.put(MediaStore.Images.Media.DATE_ADDED, System.currentTimeMillis());
        values.put(MediaStore.Images.Media.DATE_TAKEN, System.currentTimeMillis());

        Uri url = null;
        String stringUrl = null;    /* value to be returned */

        try {
            url = cr.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);

            if (source != null) {
                OutputStream imageOut = cr.openOutputStream(url);
                try {
                    source.compress(Bitmap.CompressFormat.JPEG, 50, imageOut);
                } finally {
                    imageOut.close();
                }

                long id = ContentUris.parseId(url);
                // Wait until MINI_KIND thumbnail is generated.
                Bitmap miniThumb = MediaStore.Images.Thumbnails.getThumbnail(cr, id, MediaStore.Images.Thumbnails.MINI_KIND, null);
                // This is for backward compatibility.
                storeThumbnail(cr, miniThumb, id, 50F, 50F, MediaStore.Images.Thumbnails.MICRO_KIND);
            } else {
                cr.delete(url, null, null);
                return storeToAlternateSd(source, title);
                // url = null;
            }
        } catch (Exception e) {
            if (url != null) {
                cr.delete(url, null, null);
                return storeToAlternateSd(source, title);
                // url = null;
            }
        }

        savedOnSD = false;
        if (url != null) {
            stringUrl = url.toString();
        }

        return stringUrl;
    }

    /**
     * A copy of the Android internals StoreThumbnail method, it used with the insertImage to
     * populate the android.provider.MediaStore.Images.Media#insertImage with all the correct
     * meta data. The StoreThumbnail method is private so it must be duplicated here.
     * @see android.provider.MediaStore.Images.Media (StoreThumbnail private method).
     */
    private Bitmap storeThumbnail(
            ContentResolver cr,
            Bitmap source,
            long id,
            float width,
            float height,
            int kind) {

        // create the matrix to scale it
        Matrix matrix = new Matrix();

        float scaleX = width / source.getWidth();
        float scaleY = height / source.getHeight();

        matrix.setScale(scaleX, scaleY);

        Bitmap thumb = Bitmap.createBitmap(source, 0, 0,
                source.getWidth(),
                source.getHeight(), matrix,
                true
        );

        ContentValues values = new ContentValues(4);
        values.put(MediaStore.Images.Thumbnails.KIND,kind);
        values.put(MediaStore.Images.Thumbnails.IMAGE_ID,(int)id);
        values.put(MediaStore.Images.Thumbnails.HEIGHT,thumb.getHeight());
        values.put(MediaStore.Images.Thumbnails.WIDTH,thumb.getWidth());

        Uri url = cr.insert(MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI, values);

        try {
            OutputStream thumbOut = cr.openOutputStream(url);
            thumb.compress(Bitmap.CompressFormat.JPEG, 100, thumbOut);
            thumbOut.close();
            return thumb;
        } catch (FileNotFoundException ex) {
            Log.e("IMAGE_COMPRESSION_ERROR", "File not found");
            ex.printStackTrace();
            return null;
        } catch (IOException ex) {
            Log.e("IMAGE_COMPRESSION_ERROR", "IO Exception");
            ex.printStackTrace();
            return null;
        }
    }

    /**
     * If we have issues saving into our MediaStore, save it directly to our SD card. We can then interact with this file
     * directly, opposed to pulling from the MediaStore. Again, this is a backup method if things don't work out as we
     * would expect (seeing as most devices will have a MediaStore).
     *
     * @param src
     * @param title
     * @return - the file's path
     */
    private String storeToAlternateSd(Bitmap src, String title){
        if(src == null)
            return null;

        File sdCardDirectory = new File(Environment.getExternalStorageDirectory() + File.separator + "My Cards");
        if(!sdCardDirectory.exists())
            sdCardDirectory.mkdir();

        SimpleDateFormat sdf = new SimpleDateFormat("MM-dd-yyyy - (hh.mm.a)", Locale.US);
        File image = new File(sdCardDirectory, title + " -- [" + sdf.format(new Date()) + "].jpg");
        try {
            FileOutputStream imageOut = new FileOutputStream(image);
            src.compress(Bitmap.CompressFormat.JPEG, 100, imageOut);
            imageOut.close();
            savedOnSD = true;
            return image.getAbsolutePath();
        } catch (FileNotFoundException ex) {
            ex.printStackTrace();
            return null;
        } catch (IOException ex) {
            ex.printStackTrace();
            return null;
        }
    }

    @Override
    public void onPostExecute(String url){
        if(url != null){
            Intent intent = new Intent();
            intent.setAction(Intent.ACTION_VIEW);
            if(savedOnSD){
                File file = new File(url);
                if(file.exists())
                    intent.setDataAndType(Uri.fromFile(file), "image/jpeg");
                else
                    return;
            }
            else
                intent.setDataAndType(Uri.parse(url), "image/jpeg");

            ActivityA.this.startActivity(intent);
        }
        else
            Toast.makeText(ActivityA.this, getString(R.string.error_compressing), Toast.LENGTH_SHORT).show();
    }

}

- zgc7009

---

感谢提供有用的代码片段。不过最后还是没搞清楚"imageUrl"是什么意思... - rommex

非常欢迎。它应该只是一个URL。编辑了响应。请看下面parakmiakos的答案，它似乎是最终解决方案。 - zgc7009

"insertImage"方法在API级别29中已被弃用。 应该使用MediaColumns#IS_PENDING来执行图片的插入，这样可以更好地控制其生命周期。 https://developer.android.com/reference/android/provider/MediaStore.Images.Media#insertImage(android.content.ContentResolver,%20java.lang.String,%20java.lang.String,%20java.lang.String) - undefined

Answer 3

Android 10引入了作用域存储，因此在这些文件夹中尝试写入时，您将会收到文件未找到EACCESS错误。以下是一种Kotlin解决方案，遵循当前的Android文档。

fun addImageToGallery(b: Bitmap): Uri {
    val resolver = context.applicationContext.contentResolver

    val pictureCollection = MediaStore.Images.Media
        .getContentUri(MediaStore.VOLUME_EXTERNAL_PRIMARY)

    val pictureDetails = ContentValues().apply {
        put(MediaStore.Images.Media.DISPLAY_NAME, "CurrentAlbumArt.png")
        put(MediaStore.Audio.Media.IS_PENDING, 1)
    }

    val pictureContentUri = resolver.insert(pictureCollection, pictureDetails)!!

    resolver.openFileDescriptor(pictureContentUri, "w", null).use { pfd ->
        try {
            pfd?.let {
                val fos = FileOutputStream(it.fileDescriptor)
                b.compress(Bitmap.CompressFormat.PNG, 100, fos)
                fos.close()
            }
        } catch (e: IOException) {
            e.printStackTrace()
        }
    }

    pictureDetails.clear()
    pictureDetails.put(MediaStore.Images.Media.IS_PENDING, 0)
    resolver.update(pictureContentUri, pictureDetails, null, null)
    return pictureContentUri
}

注意：我覆盖旧文件（相同文件名）并插入工作以替换我需要的内容。

- AndrewBloom

Answer 4

你还可以使用MediaStore的静态方法...

public String addImageToGallery(ContentResolver cr, File filepath) {
    try {
       return MediaStore.Images.Media.insertImage(cr, filepath.toString(), 
                                                  filepath.getName(), "Image Description");
    } catch (FileNotFoundException e) {
       e.printStackTrace();
       return e.getMessage();
    }
}

insertImage返回的String与接受答案中Uri对象上调用toString()的结果相同。

我知道这是一个比较旧的帖子，但我希望这可以帮助其他仍在寻找答案的人。

- Don Shrout