Android 备份和恢复 SQLite 数据库到 sdcard
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Backup and restore SQLite database to sdcard
提问by chrisonline
How can I backup my database to the sdcard automatically in my app? And afterward, how do I restore it?
如何在我的应用程序中自动将我的数据库备份到 SD 卡？之后，我如何恢复它？
采纳答案by chrisonline
Here is my code:
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();
回答by CommonsWare
How can i backup my database to the sdcard automatically in my app?
如何在我的应用程序中自动将我的数据库备份到 SD 卡？
Copy it using standard Java I/O. Make sure you don't have any open SQLiteDatabaseobjects, though.
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。
And afterwards how do i restore it?
之后我如何恢复它？
Copy it using standard Java I/O. Make sure you don't have any open SQLiteDatabaseobjects to the old database, though.
使用标准 Java I/O 复制它。但是，请确保SQLiteDatabase旧数据库没有任何打开的对象。
You can use getPath()on a SQLiteDatabaseobject to find out where it resides, AFAIK (haven't tried this).
您可以使用getPath()一个上SQLiteDatabase对象来找出它驻留，据我所知（没有试过）。
回答by Denny Weinberg
Thanks to the existing answers. Here is the complete class (with usage of "getDatabasePath"):
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();
}
}
}
