android - 删除图像文件后刷新图库？

Question

我的问题总能找到以下答案:

context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"
            + Environment.getExternalStorageDirectory())));

但它不适用于我的系统(Nexus4 Android 4. ...)

我可以创建一个文件并将其添加到带有此代码的 Media-DB

Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
    Uri contentUri = Uri.fromFile(file);
    mediaScanIntent.setData(contentUri);
    context.sendBroadcast(mediaScanIntent);

"file"是我要添加的新图像文件。

删除文件后，我尝试通过以下方式刷新图库

Intent intent = new Intent(Intent.ACTION_MEDIA_MOUNTED);
    Uri contentUri = Uri.parse("file://" + Environment.getExternalStorageDirectory());
    intent.setData(contentUri);
    context.sendBroadcast(intent);

或

context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"
            + Environment.getExternalStorageDirectory()))); 

但画廊中仍然有空的占位符。

我不知道为什么？...

为了安全起见，我也在 AndroidManifest.xml 中添加了我的 Activity

<intent-filter>
            <action android:name="android.intent.action.MEDIA_MOUNTED" />
            <data android:scheme="file" /> 
        </intent-filter>

但结果是一样的。有解决问题的想法吗？

Answer 1

在 KitKat 之后，您无法发送 Intent 以在整个设备的存储上运行 MediaScanner，因为这是一个 CPU I\O 密集型任务，如果每个应用程序下载图像或删除第一，称 Intent 电池很容易耗尽，因此他们决定阻止该操作。以下是您的选择:

对 pre-KitKat 使用旧方法

传递你的文件路径:

if(Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
    mContext.sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
                Uri.parse("file://" + Environment.getExternalStorageDirectory())));
} else{


    MediaScannerConnection.scanFile(mContext,  filePath, null, new MediaScannerConnection.OnScanCompletedListener() {
        /*
         *   (non-Javadoc)
         * @see android.media.MediaScannerConnection.OnScanCompletedListener#onScanCompleted(java.lang.String, android.net.Uri)
         */
        public void onScanCompleted(String path, Uri uri) 
        {
        Log.i("ExternalStorage", "Scanned " + path + ":");
        Log.i("ExternalStorage", "-> uri=" + uri);
        }
    });

}

更可靠的方法是直接更新MediaStore:

// Set up the projection (we only need the ID)
String[] projection = { MediaStore.Images.Media._ID };

// Match on the file path
String selection = MediaStore.Images.Media.DATA + " = ?";
String[] selectionArgs = new String[] { file.getAbsolutePath() };

// Query for the ID of the media matching the file path
Uri queryUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
ContentResolver contentResolver = getContentResolver();
Cursor c = contentResolver.query(queryUri, projection, selection, selectionArgs, null);
if (c.moveToFirst()) {
    // We found the ID. Deleting the item via the content provider will also remove the file
    long id = c.getLong(c.getColumnIndexOrThrow(MediaStore.Images.Media._ID));
    Uri deleteUri = ContentUris.withAppendedId(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, id);
    contentResolver.delete(deleteUri, null, null);
} else {
    // File not found in media store DB
}
c.close();