我想将示例数据库从 Assets 文件夹复制到/data/data/packagename/databases/目录，以便稍后在应用程序中使用它。
我看过很多教程和其他解决方案，例如此处 ( Copy Database from assets folder in unrooted device ) 和此处 ( copy database from assets to databases folder )，但它对我不起作用。我没有错误，但是复制的数据库是空的。我的编码有问题吗？
这是我复制数据库的代码。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
setContentView(R.layout.activity_dictionary_type);
File dbfile=new File("data/data/com.example.myidictionary/databases","DefinitionDB");
if (!dbfile.exists()) {
try {
copyDatabase(dbfile);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Toast.makeText(getApplicationContext(), "Sample data is being copied", Toast.LENGTH_LONG).show();
}
else
Toast.makeText(getApplicationContext(), "Database Exist", Toast.LENGTH_LONG).show();
}
private void copyDatabase(File dbFile) throws IOException
{
InputStream is = this.getAssets().open("DefinitionDB");
OutputStream os = new FileOutputStream(dbFile);
byte[] buffer = new byte[1024];
while (is.read(buffer) > 0)
{
os.write(buffer);
}
os.flush();
os.close();
is.close();
}
试试下面的代码，让我知道它是否工作正常？
public class DataBaseWrapper extends SQLiteOpenHelper
{
private static String TAG = DataBaseWrapper.class.getName();
private String DB_PATH; //= "/data/data/com.example.yourproject/databases/";
private static String DB_NAME = "Database.sqlite";
private SQLiteDatabase myDataBase = null;
private final Context myContext;
public DataBaseWrapper(Context context)
{
super(context, DB_NAME, null, 1);
this.myContext = context;
DB_PATH="/data/data/" + context.getPackageName() + "/" + "databases/";
Log.v("log_tag", "DBPath: " + DB_PATH);
// File f=getDatabasePath(DB_NAME);
}
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
Log.v("log_tag", "database does exist");
}else{
Log.v("log_tag", "database does not exist");
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private void copyDataBase() throws IOException{
InputStream myInput = myContext.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
private boolean checkDataBase(){
File dbFile = new File(DB_PATH + DB_NAME);
//Log.v("dbFile", dbFile + " "+ dbFile.exists());
return dbFile.exists();
}
public boolean openDataBase() throws SQLException
{
String mPath = DB_PATH + DB_NAME;
//Log.v("mPath", mPath);
myDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
//mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
return myDataBase != null;
}
@Override
public synchronized void close()
{
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db)
{
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
Log.v(TAG, "Upgrading database, this will drop database and recreate.");
}
}