使用 MediaStore 在 Android Q 中创建/复制文件

我正在尝试找到一种方法，可以处理除媒体文件（图片/视频/音频）之外的任何文件的创建和复制，以便从 Android Q 内部存储中的一个位置复制到另一个位置。在此，我在应用程序文件夹中创建了我的文件我希望将它们移动到下载文件夹或我可以在内部存储中创建的某个目录，然后移动它们。

我搜索并发现修改了下面的代码，但缺少一些使其可行的东西。有人可以帮忙吗？

ContentResolver contentResolver = getContentResolver();

ContentValues contentValues = new ContentValues();
contentValues.put(MediaStore.MediaColumns.DISPLAY_NAME, "sam.txt");
contentValues.put(MediaStore.MediaColumns.MIME_TYPE, "text/plain");
contentValues.put(MediaStore.MediaColumns.RELATIVE_PATH, Environment.DIRECTORY_DOWNLOADS);

Uri uri = contentResolver.insert(MediaStore.Files.getContentUri("external"), contentValues);

try {
    InputStream inputStream = contentResolver.openInputStream(uri);
    OutputStream outputStream = new FileOutputStream(Environment.DIRECTORY_DOWNLOADS+"/");

    byte[] buffer = new byte[1024];

    int length;

    //copy the file content in bytes
    while ((length = inputStream.read(buffer)) > 0) {
            outputStream.write(buffer, 0, length);
        }
        inputStream.close();
        outputStream.close();
        } catch (Exception e) {
           e.printStackTrace();
        }

上面是完整的代码，因为我收到错误“未知 URL”。缺什么？请帮忙。

NOTE:如果您重新安装该应用程序，MediaStore将不再识别之前创建的文件：应用重新安装后，Android 11 无法检索使用 MediaStore 创建的文件, using Intent让用户选择文件是唯一的解决方案。

1. 创建并写入文件

createAndWriteButton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        try {
            ContentValues values = new ContentValues();

            values.put(MediaStore.MediaColumns.DISPLAY_NAME, "menuCategory");       //file name                     
            values.put(MediaStore.MediaColumns.MIME_TYPE, "text/plain");        //file extension, will automatically add to file
            values.put(MediaStore.MediaColumns.RELATIVE_PATH, Environment.DIRECTORY_DOCUMENTS + "/Kamen Rider Decade/");     //end "/" is not mandatory

            Uri uri = getContentResolver().insert(MediaStore.Files.getContentUri("external"), values);      //important!

            OutputStream outputStream = getContentResolver().openOutputStream(uri);

            outputStream.write("This is menu category data.".getBytes());

            outputStream.close();

            Toast.makeText(view.getContext(), "File created successfully", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            Toast.makeText(view.getContext(), "Fail to create file", Toast.LENGTH_SHORT).show();
        }
    }
});

2.查找并读取文件

findAndReadButton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        Uri contentUri = MediaStore.Files.getContentUri("external");

        String selection = MediaStore.MediaColumns.RELATIVE_PATH + "=?";

        String[] selectionArgs = new String[]{Environment.DIRECTORY_DOCUMENTS + "/Kamen Rider Decade/"};

        Cursor cursor = getContentResolver().query(contentUri, null, selection, selectionArgs, null);

        Uri uri = null;

        if (cursor.getCount() == 0) {
            Toast.makeText(view.getContext(), "No file found in \"" + Environment.DIRECTORY_DOCUMENTS + "/Kamen Rider Decade/\"", Toast.LENGTH_LONG).show();
        } else {
            while (cursor.moveToNext()) {
                String fileName = cursor.getString(cursor.getColumnIndex(MediaStore.MediaColumns.DISPLAY_NAME));

                if (fileName.equals("menuCategory.txt")) {
                    long id = cursor.getLong(cursor.getColumnIndex(MediaStore.MediaColumns._ID));

                    uri = ContentUris.withAppendedId(contentUri, id);

                    break;
                }
            }

            if (uri == null) {
                Toast.makeText(view.getContext(), "\"menuCategory.txt\" not found", Toast.LENGTH_SHORT).show();
            } else {
                try {
                    InputStream inputStream = getContentResolver().openInputStream(uri);

                    int size = inputStream.available();

                    byte[] bytes = new byte[size];

                    inputStream.read(bytes);

                    inputStream.close();

                    String jsonString = new String(bytes, StandardCharsets.UTF_8);

                    AlertDialog.Builder builder = new AlertDialog.Builder(view.getContext());

                    builder.setTitle("File Content");
                    builder.setMessage(jsonString);
                    builder.setPositiveButton("OK", null);

                    builder.create().show();
                } catch (IOException e) {
                    Toast.makeText(view.getContext(), "Fail to read file", Toast.LENGTH_SHORT).show();
                }
            }
        }
    }
});

3. 查找并覆盖文件

findAndWriteButton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        Uri contentUri = MediaStore.Files.getContentUri("external");

        String selection = MediaStore.MediaColumns.RELATIVE_PATH + "=?";

        String[] selectionArgs = new String[]{Environment.DIRECTORY_DOCUMENTS + "/Kamen Rider Decade/"};    //must include "/" in front and end

        Cursor cursor = getContentResolver().query(contentUri, null, selection, selectionArgs, null);

        Uri uri = null;

        if (cursor.getCount() == 0) {
            Toast.makeText(view.getContext(), "No file found in \"" + Environment.DIRECTORY_DOCUMENTS + "/Kamen Rider Decade/\"", Toast.LENGTH_LONG).show();
        } else {
            while (cursor.moveToNext()) {
                String fileName = cursor.getString(cursor.getColumnIndex(MediaStore.MediaColumns.DISPLAY_NAME));

                if (fileName.equals("menuCategory.txt")) {                          //must include extension
                    long id = cursor.getLong(cursor.getColumnIndex(MediaStore.MediaColumns._ID));

                    uri = ContentUris.withAppendedId(contentUri, id);

                    break;
                }
            }

            if (uri == null) {
                Toast.makeText(view.getContext(), "\"menuCategory.txt\" not found", Toast.LENGTH_SHORT).show();
            } else {
                try {
                    OutputStream outputStream = getContentResolver().openOutputStream(uri, "rwt");      //overwrite mode, see below

                    outputStream.write("This is overwritten data。\n你就不要想起我。".getBytes());

                    outputStream.close();

                    Toast.makeText(view.getContext(), "File written successfully", Toast.LENGTH_SHORT).show();
                } catch (IOException e) {
                    Toast.makeText(view.getContext(), "Fail to write file", Toast.LENGTH_SHORT).show();
                }
            }
        }
    }
});

• 读/写模式：https://developer.android.com/training/data-storage/shared/media#open-file-descriptor

Demo: https://www.youtube.com/watch?v=idsUMiWjfnM

希望这可以帮助你。