I'm implementing a backup/restore system in my android app.
An automatic backup occures every couple of minutes. I'm trying to restore my db backup file from my sd card, after my app was uninstalled and then installed again.
Backup works, but here's the problem:
Whenever the user installs my app again, there's a file not found exception, but, if the user closes the app, and then opens it again, the restore is just fine. Somehow, the restoring faces problem when the app is first launched.
The restore must happen on first time launch.
Note: the backupExists function returns true.
@Override
public void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(backUpExists()){
restoreDB();
}
}
private boolean backUpExists()
{
try{
File sd = Environment.getExternalStorageDirectory();
if (sd.canRead()){
String backupDBPath = "myDB";
File backupedDB = new File(sd, backupDBPath);
if(backupedDB.exists()){
return true;
}
}
} catch(Exception ex) {
Toast.makeText(getBaseContext(), ex.toString(), Toast.LENGTH_LONG).show();
}
return false;
}
private void restoreDB()
{
try{
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
if (sd.canWrite()) {
String restroredDBPath = "//data//myPackage//databases//myDB";
String backupDBPath = "myDB";
File restoredDB = new File(data, restroredDBPath);
File backupedDB = new File(sd, backupDBPath);
FileChannel src = new FileInputStream(backupedDB).getChannel();
FileChannel dst = new FileOutputStream(restoredDB).getChannel();
dst.transferFrom(src, 0, src.size());
src.close();
dst.close();
Toast.makeText(getBaseContext(), restoredDB.toString(), Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG).show();
}
}
Backtrace
09-09 22:49:50.931: I/Database(23206): sqlite returned: error code = 26, msg = statement aborts at 14: [SELECT COUNT(*) FROM Photos WHERE AlbumId=0] file is encrypted or is not a database
09-09 22:49:50.931: D/AndroidRuntime(23206): Shutting down VM
09-09 22:49:50.931: W/dalvikvm(23206): threadid=1: thread exiting with uncaught exception (group=0x4151c700)
09-09 22:49:50.931: E/AndroidRuntime(23206): FATAL EXCEPTION: main
09-09 22:49:50.931: E/AndroidRuntime(23206): net.sqlcipher.database.SQLiteException: file is encrypted or is not a database
09-09 22:49:50.931: E/AndroidRuntime(23206): at net.sqlcipher.database.SQLiteQuery.native_fill_window(Native Method)
09-09 22:49:50.931: E/AndroidRuntime(23206): at net.sqlcipher.database.SQLiteQuery.fillWindow(SQLiteQuery.java:73)
09-09 22:49:50.931: E/AndroidRuntime(23206): at net.sqlcipher.database.SQLiteCursor.fillWindow(SQLiteCursor.java:290)
[snipped]
Please use this code it may help you... I have done the same with this way
For Backup
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();
Toast.makeText(getApplicationContext(), "Backup is successful to SD card", Toast.LENGTH_SHORT).show();
}
}
} catch (Exception e) {
}
For Restore
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(backupDB).getChannel();
FileChannel dst = new FileOutputStream(currentDB).getChannel();
dst.transferFrom(src, 0, src.size());
src.close();
dst.close();
Toast.makeText(getApplicationContext(), "Database Restored successfully", Toast.LENGTH_SHORT).show();
}
}
} catch (Exception e) {
}
A little dfference between both u can see in filechannel inside if condition.
try
{
String date = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/CALC/Backup";
//final
String inFileName = path+"/Calc_backup :"+date;
File dbFile = new File(inFileName);
FileInputStream fis = new FileInputStream(dbFile);
/*File dir = new File(path);
if(!dir.exists())
dir.mkdirs();*/
//Toast.makeText(getActivity(), "directory created @"+dir.getPath(), 2).show();
// String outFileName = Environment.getExternalStorageDirectory()+"Calac/hems.txt";
//String outFileName = path+"/"+date;
String outFileName = "/data/data/com.special.ResideMenuDemo/databases/Calq";
// 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);
}
Toast.makeText(getActivity(), "Restore Successfully", 2).show();
// Close the streams
output.flush();
output.close();
fis.close();
}
catch(Exception e)
{
e.printStackTrace();
}
Glenford Fernandes
The problem I feel is with reading the already existing db file. You actually are not reading it, the code is just creating a new one every time the app is installed. You will have to give the exact name of the db file you are referring to in order to read it in your getExternalEvironment function..
来源：https://stackoverflow.com/questions/18635412/restoring-sqlite-db-file