目前,我正在摆弄自己在 android 中使用 sql 数据库并创建了我的第一个应用程序。现在我想更新这个应用程序和资产文件夹中的包含数据库。我用新数据库覆盖了旧数据库,但在我的手机上它没有显示新条目。
它以某种方式保存旧条目/查询或完全保存旧 Db。我在网上查了一下,但真的找不到解决办法。在我的 dbhelper 代码下方。我必须做些什么onUpgrade
吗?或者程序是什么?
非常感谢您的帮助!
public class DataBaseHelper extends SQLiteOpenHelper {
private static String DB_PATH;
private static String DB_NAME;
private SQLiteDatabase db_object;
private final Context context;
public DataBaseHelper(Context context, String db) {
super(context, db, null, 80);
this.context = context;
DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
// DB_PATH = "/data/data/com.comp.appname/databases/";
DB_NAME = "mydatabase.sqlite";
try {
createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
try {
openDataBase();
} catch (SQLException sqle) {
throw sqle;
}
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null ? true : false;
}
private void copyDataBase() throws IOException {
InputStream myInput = context.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();
}
public void openDataBase() throws SQLException {
String myPath = DB_PATH + DB_NAME;
db_object = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if (db_object != null)
db_object.close();
super.close();
}
}