如何轻松恢复会议室数据库中的备份文件？

如何解决如何轻松恢复会议室数据库中的备份文件？

为此，我找不到合适的解决方案。甚至我都不知道如何在房间数据库中备份和还原备份文件。请帮我怎么做。

我没有任何疑问，但是堆栈溢出给我错误，这就是为什么我写这行代码的原因

我找到了备份的方法，但找不到还原数据库的解决方案 当我检查应用程序是否显示还原成功，但应用程序中不存在真实数据时

 public static boolean backUpDatabase(Context context) throws IOException {
        db.close();
        File dbFile = new File(String.valueOf(context.getDatabasePath(MainDatabase.DATABASE_NAME)));
        File sDir = new File(Environment.getExternalStorageDirectory().getAbsolutePath(),"Tuition App2");
        String fileName = "TuitionApp_BackUp.db";
        String sfPath = sDir.getAbsolutePath()+"/"+fileName;
        if (!sDir.exists()){
            sDir.mkdirs();
        }
        File saveFile = new File(sfPath);
        if (saveFile.exists()){
            saveFile.delete();
        }
        if (saveFile.createNewFile()){
            int bufferSize = 8 * 1024;
            byte[] buffer = new byte[bufferSize];
            int bytes_read = bufferSize;
            OutputStream saveDb = new FileOutputStream(sfPath);
            InputStream inDb = new FileInputStream(dbFile);
            while ((bytes_read = inDb.read(buffer,bufferSize)) > 0) {
                saveDb.write(buffer,bytes_read);
            }
            saveDb.flush();
            inDb.close();
            saveDb.close();
//saving path in to sharedPraf  sm is object of that class
            sm.saveBackFileName(context,sfPath);
            return true;
        }
        return false;
    }
    public static boolean restoreDataBase(Context context) throws FileNotFoundException {
        db.close();
        File sDir = new File(sm.getBackupFileName(context));
        File finalFile = new File(sDir.getAbsolutePath());
        InputStream inputStream = context.getContentResolver().openInputStream(Uri.fromFile(finalFile));
        File oldDb = context.getDatabasePath(MainDatabase.DATABASE_NAME);
        if ( inputStream!= null){
            try {
                copyFile((FileInputStream) inputStream,new FileOutputStream(oldDb));
                return true;
            } catch (IOException e) {
                e.printstacktrace();
            }
        }

        return false;
    }
    public static void copyFile(FileInputStream fromFile,FileOutputStream toFile) throws IOException {
        FileChannel fromChannel = null;
        FileChannel tochannel = null;
        try {
            fromChannel = fromFile.getChannel();
            tochannel = toFile.getChannel();
            fromChannel.transferTo(0,fromChannel.size(),tochannel);

        } finally {
            try {
                if (fromChannel != null) {
                    fromChannel.close();
                }
            } finally {
                if (tochannel != null) {
                    tochannel.close();
                }
            }
        }
    }

解决方法

这是使用SQLite的，但是过程应该相同：

https://medium.com/@gavingt/refactoring-my-backup-and-restore-feature-to-comply-with-scoped-storage-e2b6c792c3b

下面的内容还将向您展示如何遵守作用域存储，因为您的操作方式现在在Android 11上根本无法使用：

https://developer.android.com/preview/privacy/storage

您可能还想禁用onOpen()中的预写日志记录。这就是SQLite中的样子：

    @Override
public void onOpen(SQLiteDatabase db) {
    super.onOpen(db);
    //disable write-ahead logging to make backup/restore work on all devices.
    db.disableWriteAheadLogging();
}

请参见以下链接，以将onOpen()回调放在Room中的位置：

https://medium.com/@srinuraop/database-create-and-open-callbacks-in-room-7ca98c3286ab