如何在 Android 10 (Android Q) 中访问外部存储？

Question

我刚刚将我的源代码迁移到 Androidx，因为我这样做了我的共享 function 以共享声音不再起作用。 Logcat 说：

Failed to save file: /storage/emulated/0/appfolder/testsound.mp3 (Permission denied)

这是它保存声音的部分：

            final String fileName = soundObject.getItemName() + ".mp3";
            File storage = Environment.getExternalStorageDirectory();
            File directory = new File(storage.getAbsolutePath() + "/appfolder/");
            directory.mkdirs();
            final File file = new File(directory, fileName);
            InputStream in = view.getContext().getResources().openRawResource(soundObject.getItemID());

            try{
                Log.i(LOG_TAG, "Saving sound " + soundObject.getItemName());
                OutputStream out = new FileOutputStream(file);
                byte[] buffer = new byte[1024];

                int len;
                while ((len = in.read(buffer, 0, buffer.length)) != -1){
                    out.write(buffer, 0 , len);
                }
                in.close();
                out.close();

            } catch (IOException e){

                Log.e(LOG_TAG, "Failed to save file: " + e.getMessage());
            }

这是它共享声音的代码：

try{
                            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1){


                                if (ActivityCompat.checkSelfPermission(view.getContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
                                    ActivityCompat.requestPermissions((Activity) view.getContext(), new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);

                                }else {
                                    final String AUTHORITY = view.getContext().getPackageName() + ".fileprovider";
                                    Uri contentUri = FileProvider.getUriForFile(view.getContext(), AUTHORITY, file);
                                    final Intent intent = new Intent(Intent.ACTION_SEND);
                                    intent.putExtra(Intent.EXTRA_STREAM, contentUri);
                                    intent.setType("audio/mp3");
                                    view.getContext().startActivity(Intent.createChooser(intent, "Share sound via..."));
                                }


                            }
                            else {
                                final Intent intent = new Intent(Intent.ACTION_SEND);
                                Uri fileUri = Uri.parse(file.getAbsolutePath());
                                intent.putExtra(Intent.EXTRA_STREAM, fileUri);
                                intent.setType("audio/mp3");
                                view.getContext().startActivity(Intent.createChooser(intent, "Share sound via..."));
                            }

                        } catch (Exception e){
                            Log.e(LOG_TAG, "Failed to share sound: " + e.getMessage());
                        }
                    }

我需要改变什么，我怎样才能使每个人无论他使用哪个 Android 版本（minSdkVersion 16）都可以下载和共享声音？

可悲的是，我在 atm 收到了很多差评，因为没有人可以分享（甚至 Android 9 及以下，尽管他们曾经能够分享）谢谢

Answer 1

如果您的目标 Android 10 或更高，请在您的应用清单文件中将 requestLegacyExternalStorage 的值设置为 true：

<manifest ... >
  <!-- This attribute is "false" by default on apps targeting
       Android 10 or higher. -->
  <application android:requestLegacyExternalStorage="true" ... >
    ...
  </application>
</manifest>

访问文件

要加载媒体文件，请从ContentResolver调用以下方法之一：

 Uri contentUri = ContentUris.withAppendedId(
        MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
        cursor.getLong(Integer.parseInt(BaseColumns._ID)));
String fileOpenMode = "r";
ParcelFileDescriptor parcelFd = resolver.openFileDescriptor(uri, fileOpenMode);
if (parcelFd != null) {
    int fd = parcelFd.detachFd();
    // Pass the integer value "fd" into your native code. Remember to call
    // close(2) on the file descriptor when you're done using it.
}

在运行 Android 10（API 级别 29）及更高版本的设备上，您的应用可以通过使用 IS_PENDING 标志在将媒体文件写入磁盘时获得对媒体文件的独占访问权限。

ContentValues values = new ContentValues();
values.put(MediaStore.Images.Media.DISPLAY_NAME, "IMG1024.JPG");
values.put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg");
values.put(MediaStore.Images.Media.IS_PENDING, 1);

ContentResolver resolver = context.getContentResolver();
Uri collection = MediaStore.Images.Media.getContentUri(MediaStore.VOLUME_EXTERNAL_PRIMARY);
Uri item = resolver.insert(collection, values);

try (ParcelFileDescriptor pfd = resolver.openFileDescriptor(item, "w", null)) {
    // Write data into the pending image.
} catch (IOException e) {
    e.printStackTrace();
}

// Now that we're finished, release the "pending" status, and allow other apps
// to view the image.
values.clear();
values.put(MediaStore.Images.Media.IS_PENDING, 0);
resolver.update(item, values, null, null);

Answer 2

我被困了很长时间，这对我来说很好

  StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
    StrictMode.setVmPolicy(builder.build());
    File = new File(filepath);

并且不要忘记在清单文件中请求旧版存储。

  <application android:requestLegacyExternalStorage="true" >