以下是導入和導出SQLite數(shù)據(jù)庫的工作方法。在除Android Pie外的所有android版本中，其工作情況都很好。當我嘗試導入Android Pie時，它顯示成功的Toast，但未還原數(shù)據(jù)庫。誰能幫我解決Android Pie（API 28）問題。private void importDB() {    try {        File sd = Environment.getExternalStorageDirectory();        File cur_db_pat = new File(this.getDatabasePath(DATABASE_NAME).getAbsolutePath());        if (sd.canWrite()) {            String backupDBPath = bac_dir_nam +"/" + DATABASE_NAME;            File currentDB = new File(sd, backupDBPath);            FileChannel src = new FileInputStream(currentDB).getChannel();            FileChannel dst = new FileOutputStream(cur_db_pat).getChannel();            dst.transferFrom(src, 0, src.size());            src.close();            dst.close();            Toast.makeText(getBaseContext(), cur_db_pat.toString(),                    Toast.LENGTH_LONG).show();        }    } catch (Exception e) {        Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG)                .show();    }}private void exportDB() {    try {        File sd = Environment.getExternalStorageDirectory();        File cur_db_pat = new File(this.getDatabasePath(DATABASE_NAME).getAbsolutePath());        if (sd.canWrite()) {            String backupDBPath = bac_dir_nam+"/" + DATABASE_NAME;            File backupDB = new File(sd, backupDBPath);            FileChannel src = new FileInputStream(cur_db_pat).getChannel();            FileChannel dst = new FileOutputStream(backupDB).getChannel();            dst.transferFrom(src, 0, src.size());            src.close();            dst.close();            Toast.makeText(getBaseContext(), backupDB.toString(),                    Toast.LENGTH_LONG).show();        }    } catch (Exception e) {        Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG)                .show();    }}我對文件系統(tǒng)沒有太多經(jīng)驗。因此，舉個例子會很有幫助。