我搜索了很多有关备份/还原sqlite数据库的搜索,我找到了将SQLite文件复制到SD卡的代码,这是代码
private void exportDB() {
try {
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
if (sd.canWrite()) {
String currentDBPath = "//data//" + "<package name>"
+ "//databases//" + "<db name>";
String backupDBPath = "<destination>";
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(getApplicationContext(), "Backup Successful!",
Toast.LENGTH_SHORT).show();
}
} catch (Exception e) {
Toast.makeText(getApplicationContext(), "Backup Failed!", Toast.LENGTH_SHORT)
.show();
}
}
现在,我在SD卡中有数据库文件(.db(,我想将数据还原到应用程序,我尝试了此代码,但它不是还原数据到App
private void importDB() {
try {
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
if (sd.canWrite()) {
String currentDBPath = "//data//" + "<package name>"
+ "//databases//" + "<database name>";
String backupDBPath = "<backup db filename>"; // From SD directory.
File backupDB = new File(data, currentDBPath);
File currentDB = new File(sd, backupDBPath);
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(), "Import Successful!",
Toast.LENGTH_SHORT).show();
}
} catch (Exception e) {
Toast.makeText(getApplicationContext(), "Import Failed!", Toast.LENGTH_SHORT)
.show();
}
}
我的问题是如何将SQLite数据库还原到我的应用?
这是工作db还原的核心代码(来自 if (dbfile
..在 try
中(。
private static final int BUFFERSZ = 32768;
private byte[] buffer = new byte[BUFFERSZ];
........
dbfile = new File(currentdbfilename);
.......
if (dbfile.delete()) {
origdeleted = true;
}
FileInputStream bkp = new FileInputStream(backupfilename);
OutputStream restore = new FileOutputStream(currentdbfilename);
copylength = 0;
while ((copylength = bkp.read(buffer)) > 0) {
restore.write(buffer, 0, copylength);
}
restore.flush();
restore.close();
restoredone = true;
bkp.close();
主要区别是我删除了数据库文件并使用写入而不是转移。后来和成功还原后,我还使用以下来重新启动该应用程序(可能是过高的功能,但对我有用(,因为您可以获得不可预测的结果(我认为可以从内存/缓存数据访问原始数据库的某些部分(: -
Intent i = getBaseContext().getPackageManager()
.getLaunchIntentForPackage( getBaseContext().getPackageName() );
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
finish();
startActivity(i);
System.exit(0);