创建新的文件权限被拒绝

Question

我发现这种方法可以将db导出为CSV，但是当它创建一个文件时，它表示权限被拒绝我已经在清单中授予了权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

这是代码

private void exportDB() {

    File dbFile = getDatabasePath("db_journal.db");
    db = new JournalDB(getApplicationContext());
    File exportDir = new File(Environment.getExternalStorageDirectory(), "");
    if (!exportDir.exists()) {
        exportDir.mkdirs();
    }

    File file = new File(exportDir, "ojt.csv");
    try {
        file.createNewFile();
        CSVWriter csvWrite = new CSVWriter(new FileWriter(file));
        SQLiteDatabase sql = db.getReadableDatabase();
        Cursor curCSV = sql.rawQuery("SELECT * FROM logs", null);
        csvWrite.writeNext(curCSV.getColumnNames());
        while (curCSV.moveToNext()) {

            String arrStr[] = {curCSV.getString(0), curCSV.getString(1), curCSV.getString(2),curCSV.getString(3), curCSV.getString(4), curCSV.getString(5), curCSV.getString(6)};
            csvWrite.writeNext(arrStr);
        }
        csvWrite.close();
        curCSV.close();
    } catch (Exception sqlEx) {
        Log.e("ProfileMain", sqlEx.getMessage(), sqlEx);
    }
}