将SQLite数据库备份并还原到SD卡

Question

如何在我的应用程序中自动将数据库备份到SD卡？然后,我该如何恢复它？

Answer 1

这是我的代码:

    // Local database
    InputStream input = new FileInputStream(from);

    // create directory for backup
    File dir = new File(DB_BACKUP_PATH);
    dir.mkdir();

    // Path to the external backup
    OutputStream output = new FileOutputStream(to);

    // transfer bytes from the Input File to the Output File
    byte[] buffer = new byte[1024];
    int length;
    while ((length = input.read(buffer))>0) {
        output.write(buffer, 0, length);
    }

    output.flush();
    output.close();
    input.close();

Answer 2

如何在我的应用程序中自动将数据库备份到SD卡？

使用标准Java I/O复制它.但是请确保您没有任何打开的SQLiteDatabase对象.

然后如何恢复它？

使用标准Java I/O复制它.但是,请确保您没有任何打开SQLiteDatabase旧对象的打开对象.

您可以getPath()在SQLiteDatabase对象上使用它来查找它所在的位置,AFAIK(尚未尝试过).

Answer 3

感谢现有的答案.这是完整的类(使用"getDatabasePath"):

package com.levionsoftware.bills.data.db;

import android.content.Context;
import android.os.Environment;
import android.widget.Toast;

import com.levionsoftware.bills.MyApplication;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.channels.FileChannel;

/**
 * Created by denny on 16/05/2016.
 * Source: http://stackoverflow.com/questions/18322401/is-it-posible-backup-and-restore-a-database-file-in-android-non-root-devices
 */
public class BackupAndRestore {
    public static void importDB(Context context) {
        try {
            File sd = Environment.getExternalStorageDirectory();
            if (sd.canWrite()) {
                File backupDB = context.getDatabasePath(DBHandler.getDBName());
                String backupDBPath = String.format("%s.bak", DBHandler.getDBName());
                File currentDB = new File(sd, backupDBPath);

                FileChannel src = new FileInputStream(currentDB).getChannel();
                FileChannel dst = new FileOutputStream(backupDB).getChannel();
                dst.transferFrom(src, 0, src.size());
                src.close();
                dst.close();

                MyApplication.toastSomething(context, "Import Successful!");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void exportDB(Context context) {
        try {
            File sd = Environment.getExternalStorageDirectory();
            File data = Environment.getDataDirectory();

            if (sd.canWrite()) {
                String backupDBPath = String.format("%s.bak", DBHandler.getDBName());
                File currentDB = context.getDatabasePath(DBHandler.getDBName());
                File backupDB = new File(sd, backupDBPath);

                FileChannel src = new FileInputStream(currentDB).getChannel();
                FileChannel dst = new FileOutputStream(backupDB).getChannel();
                dst.transferFrom(src, 0, src.size());
                src.close();
                dst.close();

                MyApplication.toastSomething(context, "Backup Successful!");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}