问题
I\'d like to add a feature to my Android app that automatically backs up the SQLite database to the SD card.
What\'s the best way to go about this? Are any examples or tutorials available?
回答1:
SQLite databases are completely self-contained files and are portable — you can just copy the entire file straight to the SD card.
Though first I'd check whether an SD card is installed in the device, and what its path is (using Environment.getExternalStorageDirectory()).
回答2:
This code works for me!
try {
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
if (sd.canWrite()) {
String currentDBPath = "//data//{package name}//databases//{database name}";
String backupDBPath = "{database name}";
File currentDB = new File(data, currentDBPath);
File backupDB = new File(sd, backupDBPath);
if (currentDB.exists()) {
FileChannel src = new FileInputStream(currentDB).getChannel();
FileChannel dst = new FileOutputStream(backupDB).getChannel();
dst.transferFrom(src, 0, src.size());
src.close();
dst.close();
}
}
} catch (Exception e) {
}
Does anyone know if this will work on non-root phones? I have only tried it on a rooted G1.
回答3:
try {
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
if (sd.canWrite()) {
String currentDBPath = "//data//"+ packageName +"//databases//"+dbList[0];
String backupDBPath = dbList[0];
File currentDB = new File(data, currentDBPath);
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();
Toast.makeText(getBaseContext(), backupDB.toString(), Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG).show();
}
That works as opposed to the above examples in which the "/" are "\" wasted 20 minutes of my life figuring that out, but I really should have seen that sooner. The Toast will tell you where the file has been place or tell you what's wrong when it doesn't work.
回答4:
I answered a question similar to this with a method you can place in your SQLiteOpenHelper. It is as simple as copying the db file from some kind of external storage, to the internal application storage. There is also some extra code that opens and reads the db file to make sure it is in the proper state for Android to make database calls to it.
回答5:
public static void BackupDatabase() throws IOException
{
boolean success =true;
File file = null;
file = new File(Environment.getExternalStorageDirectory() +"/M.O.L.S_Backup");
if (file.exists())
{
success =true;
}
else
{
success = file.mkdir();
}
if (success)
{
String inFileName = "/data/data/com.sygic.sdk.demo/databases/MOLS_DB.s3db";
File dbFile = new File(inFileName);
FileInputStream fis = new FileInputStream(dbFile);
String outFileName = Environment.getExternalStorageDirectory()+"/M.O.L.S_Backup/MOLS_DB.s3db";
// Open the empty db as the output stream
OutputStream output = new FileOutputStream(outFileName);
// Transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = fis.read(buffer))>0) {
output.write(buffer, 0, length);
}
output.flush();
output.close();
fis.close();
}
}
回答6:
You have to give the permission android.permission.WRITE_EXTERNAL_STORAGE in your application. It works fine on unrooted devices.
回答7:
I don't know what happens if the phone is rooted or not but you should write your files to:
/Android/data/{package_name}/files/
This will work whether it's rooted or not.
回答8:
You find your Database Name in the Database Adapter if you are new into this.
Note that you can do this for SharedPreferences too but keep in mind to change your Context.MODE_PRIVATE to Context.MODE_MULTI_PROCESS.
SharedPreferences_name should look like this = ExportSP("temp.xml");
String currentPathForSharedPreferences = "/data/"+ context.getPackageName() +"/shared_prefs/"+ SharedPreferences_name;
For export
exportDB("MyDbName");
private void exportDB(String db_name){
File sd = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) +
File.separator + "Your Backup Folder"+
File.separator );
boolean success = true;
if (!sd.exists()) {
success = sd.mkdir();
}
if (success) {
File data = Environment.getDataDirectory();
FileChannel source=null;
FileChannel destination=null;
String currentDBPath = "/data/"+ context.getPackageName() +"/databases/"+db_name;
String backupDBPath = db_name;
File currentDB = new File(data, currentDBPath);
File backupDB = new File(sd, backupDBPath);
try {
source = new FileInputStream(currentDB).getChannel();
destination = new FileOutputStream(backupDB).getChannel();
destination.transferFrom(source, 0, source.size());
source.close();
destination.close();
Toast.makeText(this, "Please wait", Toast.LENGTH_SHORT).show();
} catch(IOException e) {
e.printStackTrace();
}
}}
For import
importDB("MyDbName");
private void importDB(String db_name){
File sd = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) +
File.separator + "Your Backup Folder"+
File.separator );
File data = Environment.getDataDirectory();
FileChannel source=null;
FileChannel destination=null;
String backupDBPath = "/data/"+ context.getPackageName() +"/databases/"+db_name;
String currentDBPath = db_name;
File currentDB = new File(sd, currentDBPath);
File backupDB = new File(data, backupDBPath);
try {
source = new FileInputStream(currentDB).getChannel();
destination = new FileOutputStream(backupDB).getChannel();
destination.transferFrom(source, 0, source.size());
source.close();
destination.close();
Toast.makeText(this, "Please wait", Toast.LENGTH_SHORT).show();
} catch(IOException e) {
e.printStackTrace();
}
}
回答9:
@skeniver's code works for me. I just want to add the following:
Use:
String currentDbPath = getApplicationContext().getDatabasePath("{database name}");
It will give you your database path. It is better to use that instead of hardcoding the path, like:
String currentDbPath = "//data//{package name}//databases//{database name}";
回答10:
@Override
protected void onCreate(Bundle savedInstanceState) {
try {
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
if (sd.canWrite()) {
String currentDBPath = "//data//"+getPackageName()+"//databases//"+DATABASE_NAME+"";
String backupDBPath = "backup.db";
File currentDB = new File(data, currentDBPath);
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();
Toast.makeText(getBaseContext(), backupDB.toString(), Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG).show();
}
}
来源：https://stackoverflow.com/questions/1995320/how-do-i-backup-a-database-file-to-the-sd-card-on-android