为了支持Android 11存储,我已经成功实现了Scoped Storage - MediaStore API。然而,我遇到了一个场景,不确定如何解决。场景是:当应用程序第一次启动时,我们已经在Documents文件夹下创建了文件夹,并且能够读写该文件夹中的文件,而无需创建任何重复的文件夹。然而,如果我清除数据并重新登录应用程序,则无法获取已创建的文件夹,并且每次都会创建一个新的带有重复名称后缀为(2),(3)等的文件夹。
请查看我尝试过的代码以及截图。
清除应用程序数据后,在每个实例中,此方法getDataColumn()返回空字符串"",在调试期间我发现
请从文件管理器中查找下面的文档文件夹:
请查看我尝试过的代码以及截图。
File folder = null;
String folderName = "Duration";
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.Q) {
Uri contentUri = MediaStore.Files.getContentUri("external");
String filePath = FileUtils.readFileExternalStorage(contentUri,context,folderName).getPath();
if (!TextUtils.isEmpty(filePath) && FileUtils.isFileExisting(filePath)) {
folder = new File(filePath);
} else {
Uri uri = FileUtils.createFileExternalStorage(contentUri,context,folderName),Environment.DIRECTORY_DOCUMENTS);
Commons.print("URI "+uri.getPath());
folder = new File(FileUtils.getPath(context,uri));
}
if (!folder.exists()) {
folder.mkdirs();
}
} else {
folder = getStorageDir(folderName);
bmodel.deleteFiles(getStorageDir(folderName) + "/", filename);
}
File file = new File(folder, filename );
if(file.exists()) {
file.delete();
}
if (SynchronizationHelper.bcpJSONData != null) {
FileOutputStream outputStream;
try {
Commons.print("FilePath " + file.getPath());
outputStream = new FileOutputStream(file);//context.openFileOutput(filename, Context.MODE_PRIVATE);
outputStream.write(SynchronizationHelper.bcpJSONData.getBytes());
outputStream.close();
outputStream = null;
SynchronizationHelper.bcpJSONData = null;
} catch (Exception e) {
e.printStackTrace();
}
}
这是 FileUtils 类:
@RequiresApi(api = Build.VERSION_CODES.Q)
public static File readFileExternalStorage(Uri contentUri, Context context, String filename) {
final String selection = MediaStore.Files.FileColumns.DISPLAY_NAME + "=?";
final String[] selectionArgs = new String[] {filename};
return new File(getDataColumn(context,contentUri,selection,selectionArgs));
}
@RequiresApi(api = Build.VERSION_CODES.Q)
public static Uri createFileExternalStorage(Uri contentUri, Context context, String filename, String folder) {
ContentValues values = new ContentValues();
values.put(MediaStore.MediaColumns.DISPLAY_NAME, filename);
values.put(MediaStore.MediaColumns.RELATIVE_PATH, folder);
return context.getContentResolver().insert(contentUri, values);
}
public static String getDataColumn(Context context, Uri uri,
String selection, String[] selectionArgs) {
Cursor cursor = null;
final String column = "_data";
final String[] projection = { column };
try {
cursor = context.getContentResolver().query(uri, projection,
selection, selectionArgs, null);
if (cursor != null && cursor.moveToFirst()) {
final int index = cursor.getColumnIndexOrThrow(column);
return cursor.getString(index);
}
} finally {
if (cursor != null)
cursor.close();
}
return "";
}
@TargetApi(Build.VERSION_CODES.KITKAT)
@SuppressLint("NewApi")
public static String getPath(final Context context, final Uri uri) {
// check here to KITKAT or new version
final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
// DocumentProvider
if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
// ExternalStorageProvider
if (isExternalStorageDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];
if ("primary".equalsIgnoreCase(type)) {
return Environment.getExternalStorageDirectory() + "/"
+ split[1];
}
}
// DownloadsProvider
else if (isDownloadsDocument(uri)) {
final String id = DocumentsContract.getDocumentId(uri);
final Uri contentUri = ContentUris.withAppendedId(
Uri.parse("content://downloads/public_downloads"),
Long.valueOf(id));
return getDataColumn(context, contentUri, null, null);
}
// MediaProvider
else if (isMediaDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];
Uri contentUri = null;
if ("image".equals(type)) {
contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
} else if ("video".equals(type)) {
contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
} else if ("audio".equals(type)) {
contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
}
final String selection = "_id=?";
final String[] selectionArgs = new String[] { split[1] };
return getDataColumn(context, contentUri, selection,
selectionArgs);
}
}
// MediaStore (and general)
else if ("content".equalsIgnoreCase(uri.getScheme())) {
// Return the remote address
if (isGooglePhotosUri(uri))
return uri.getLastPathSegment();
return getDataColumn(context, uri, null, null);
}
// File
else if ("file".equalsIgnoreCase(uri.getScheme())) {
return uri.getPath();
}
return "";
}
清除应用程序数据后,在每个实例中,此方法getDataColumn()返回空字符串"",在调试期间我发现
try
块内的游标未从中获取任何内容。请从文件管理器中查找下面的文档文件夹: