通过在Android中制作对象，使用sqlite数据库验证登录

如何解决通过在Android中制作对象，使用sqlite数据库验证登录

| 我正在尝试开发一个Android应用程序，允许用户使用其名称和密码登录数据库。 我在以下链接上尝试了解决方案： 使用sqlite验证Android中的登录名 它对我有用，但问题是，只有通过编辑清单文件并将登录活动替换为其他活动，代码才能进入项目。  我的意思是，当项目在其DDMS中创建数据库时，它可以工作。否则，它永远不允许在任何新的仿真器和设备上登录。 我正在使用Assets文件夹中的数据库表。 我的sqlHelper类是：

public class sqlHelper extends sqliteOpenHelper implements DatabaseMetaData
{   
public static sqliteDatabase dbsqlite;
protected sqliteDatabase db = null;

private final Context myContext;

public sqlHelper(Context context) {
    super(context,DATABASE_NAME,null,1);
    this.myContext = context;

}


public void onCreate(sqliteDatabase db) {
    // check if exists and copy database from resource
    createDB();

}

@Override
public void onUpgrade(sqliteDatabase db,int oldVersion,int newVersion) {
    Log.w(\"sqlHelper\",\"Upgrading database from version \" + oldVersion
            + \" to \" + newVersion + \",which will destroy all old data\");
    onCreate(db);
}

public void createDatabase() {
    createDB();
}

private void createDB() {

    boolean dbExist = DBExists();

    if (!dbExist) {
        copyDBFromresource();
    }
}

private boolean DBExists() {

    sqliteDatabase db = null;

    try {
        String databasePath = DATABASE_PATH + DATABASE_NAME;
        db = sqliteDatabase.openDatabase(databasePath,sqliteDatabase.OPEN_READWRITE);
        db.setLocale(Locale.getDefault());
        db.setLockingEnabled(true);
        db.setVersion(1);

    } catch (sqliteException e) {

        Log.e(\"sqlHelper\",\"database not found\");

    }

    if (db != null) {

        db.close();

    }

    return db != null ? true : false;
}

private void copyDBFromresource() {

    InputStream inputStream = null;
    OutputStream outStream = null;
    String dbFilePath = DATABASE_PATH + DATABASE_NAME;

    try {

        inputStream = myContext.getAssets().open(DATABASE_NAME);

        outStream = new FileOutputStream(dbFilePath);

        byte[] buffer = new byte[1024];
        int length;
        while ((length = inputStream.read(buffer)) > 0) {
            outStream.write(buffer,length);
        }

        outStream.flush();
        outStream.close();
        inputStream.close();

    } catch (IOException e) {

        throw new Error(\"Problem copying database from resource file.\");

    }

}

public void openDataBase() throws sqlException {

    String myPath = DATABASE_PATH + DATABASE_NAME;
    dbsqlite = sqliteDatabase.openDatabase(myPath,sqliteDatabase.OPEN_READWRITE);

}


@Override
public synchronized void close() {

    if (dbsqlite != null)
        dbsqlite.close();

    super.close();

}
   }

我的DatabaseMetaData接口类是：

    public interface DatabaseMetaData {
String DATABASE_PATH = \"/data/data/com.dbApp/databases/\";

String DATABASE_NAME = \"dbApp\";

    String TABLE_USERLIST = \"UserList\";
String TABLE_CUSTOMER = \"Customer\";


//UserList
String COLUMN_USER_NAME = \"User_Name\";
String COLUMN_PASSWORD = \"Password\";

    //Customer
String COLUMN_ID = \"_id\";
String COLUMN_LISTID = \"ListID\";
String COLUMN_NAME = \"Name\";
String COLUMN_COMPANYNAME = \"CompanyName\";
String COLUMN_FirsTNAME = \"FirstName\";
String COLUMN_LASTNAME = \"LastName\";
    }

在LoginActivity中，我使用以下方法：

 protected boolean tryLogin(String username,String password)
{
    try{
        Cursor cursor = null;
        cursor = db.rawQuery(\"select \" + DatabaseMetaData.COLUMN_PASSWORD + \" from \" + DatabaseMetaData.TABLE_USERLIST + \" where \" + DatabaseMetaData.COLUMN_USER_NAME + \" = \" + \"\'\" +username+ \"\'\",null);

        //cursor = db.rawQuery(\"select password from UserList where user_name=\'\" + username + \"\'\",null);
        if (cursor.movetoFirst()) {
            String str = cursor.getString(0);
            if (password.equals(str)) {
                cursor.close();
                return true;

            }else{

                return false;
            }
        }cursor.close();
    }

请帮我..