我正在按照教程进行登录页面。
如果我在注册后直接登录，我的登录工作正常。
然而，当我再次运行应用程序时，使用与我注册时相同的登录信息， 它将举报一条消息，说明“密码/用户名无效”， 我查看了我的数据库，数据在我的数据库中 但我不知道为什么我不能登录..
这是我的代码： 有人可以帮帮我吗？
LoginDataBaseAdapter.java
public class LoginDataBaseAdapter {
static final String DATABASE_NAME = "login.db";
static final int DATABASE_VERSION = 1;
public static final int NAME_COLUMN = 1;
// TODO: Create public field for each column in your table.
// SQL Statement to create a new database.
static final String DATABASE_CREATE = "create table "+"LOGIN"+
"( " +"ID"+" integer primary key autoincrement,"+ "USERNAME text,PASSWORD text); ";
// Variable to hold the database instance
public SQLiteDatabase db;
// Context of the application using the database.
private final Context context;
// Database open/upgrade helper
private DataBaseHelper dbHelper;
public LoginDataBaseAdapter(Context _context)
{
context = _context;
dbHelper = new DataBaseHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public LoginDataBaseAdapter open() throws SQLException
{
db = dbHelper.getWritableDatabase();
return this;
}
public void close()
{
db.close();
}
public SQLiteDatabase getDatabaseInstance()
{
return db;
}
public void insertEntry(String userName,String password)
{
ContentValues newValues = new ContentValues();
// Assign values for each row.
newValues.put("USERNAME", userName);
newValues.put("PASSWORD",password);
// Insert the row into your table
db.insert("LOGIN", null, newValues);
///Toast.makeText(context, "Reminder Is Successfully Saved", Toast.LENGTH_LONG).show();
}
public int deleteEntry(String UserName)
{
//String id=String.valueOf(ID);
String where="USERNAME=?";
int numberOFEntriesDeleted= db.delete("LOGIN", where, new String[]{UserName}) ;
// Toast.makeText(context, "Number fo Entry Deleted Successfully : "+numberOFEntriesDeleted, Toast.LENGTH_LONG).show();
return numberOFEntriesDeleted;
}
public String getSinlgeEntry(String userName)
{
Cursor cursor=db.query("LOGIN", null, " USERNAME=?", new String[]{userName}, null, null, null);
if(cursor.getCount()<1) // UserName Not Exist
{
cursor.close();
return "NOT EXIST";
}
cursor.moveToFirst();
String password= cursor.getString(cursor.getColumnIndex("PASSWORD"));
cursor.close();
return password;
}
public void updateEntry(String userName,String password)
{
// Define the updated row content.
ContentValues updatedValues = new ContentValues();
// Assign values for each row.
updatedValues.put("USERNAME", userName);
updatedValues.put("PASSWORD",password);
String where="USERNAME = ?";
db.update("LOGIN",updatedValues, where, new String[]{userName});
}
public class DataBaseHelper extends SQLiteOpenHelper
{
public DataBaseHelper(Context context, String name,CursorFactory factory, int version)
{
super(context, name, factory, version);
}
// Called when no database exists in disk and the helper class needs
// to create a new one.
@Override
public void onCreate(SQLiteDatabase _db)
{
_db.execSQL(LoginDataBaseAdapter.DATABASE_CREATE);
}
// Called when there is a database version mismatch meaning that the version
// of the database on disk needs to be upgraded to the current version.
@Override
public void onUpgrade(SQLiteDatabase _db, int _oldVersion, int _newVersion)
{
// Log the version upgrade.
Log.w("TaskDBAdapter", "Upgrading from version " +_oldVersion + " to " +_newVersion + ", which will destroy all old data");
// Upgrade the existing database to conform to the new version. Multiple
// previous versions can be handled by comparing _oldVersion and _newVersion
// values.
// The simplest case is to drop the old table and create a new one.
_db.execSQL("DROP TABLE IF EXISTS " + "TEMPLATE");
// Create a new one.
onCreate(_db);
}
}
}//close DBAdapter
homeactivity.java
public class homeActivity extends Activity{
Button btnSignIn,btnSignUp;
Button btnAbout;
LoginDataBaseAdapter loginDataBaseAdapter;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.homescreen);
// create a instance of SQLite Database
loginDataBaseAdapter=new LoginDataBaseAdapter(this);
loginDataBaseAdapter=loginDataBaseAdapter.open();
// Get The Reference Of Buttons
btnSignIn=(Button)findViewById(R.id.buttonSignIN);
btnSignUp=(Button)findViewById(R.id.buttonSignUP);
btnAbout=(Button)findViewById(R.id.aboutBTN);
// Set OnClick Listener on SignUp button
btnSignUp.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
/// Create Intent for SignUpActivity abd Start The Activity
Intent intentSignUP=new Intent(getApplicationContext(),SignUpActivity.class);
startActivity(intentSignUP);
}
});
// set OnClick Listener on About button
btnAbout.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
/// Create Intent for About and start activity
Intent intentAbout=new Intent(getApplicationContext(),about.class);
startActivity(intentAbout);
}
});
}
// Methods to handleClick Event of Sign In Button
public void signIn(View V)
{
final Dialog dialog = new Dialog(homeActivity.this);
dialog.setContentView(R.layout.login);
dialog.setTitle("Login");
// get the Refferences of views
final EditText editTextUserName=(EditText)dialog.findViewById(R.id.editTextUserNameToLogin);
final EditText editTextPassword=(EditText)dialog.findViewById(R.id.editTextPasswordToLogin);
Button btnSignIn=(Button)dialog.findViewById(R.id.buttonSignIn);
// Set On ClickListener
btnSignIn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// get The User name and Password
String userName=editTextUserName.getText().toString();
String password=editTextPassword.getText().toString();
// fetch the Password form database for respective user name
String storedPassword=loginDataBaseAdapter.getSinlgeEntry(userName);
// check if the Stored password matches with Password entered by user
if(password.equals(storedPassword))
{
Toast.makeText(homeActivity.this, "Welcome," + userName, Toast.LENGTH_LONG).show();
dialog.dismiss();
Intent mainact=new Intent(getApplicationContext(),MainActivity.class);
mainact.putExtra("priceEdit", "floatvalue");
mainact.putExtra("pumpEdit", "floatvalue");
startActivity(mainact);
}
else
{
Toast.makeText(homeActivity.this, "User Name or Password does not match", Toast.LENGTH_LONG).show();
}
}
});
dialog.show();
}
@Override
protected void onDestroy() {
super.onDestroy();
// Close The Database
loginDataBaseAdapter.close();
}
}
答案 0 :(得分：0)
不确定，但这里有一些想法：
检查大小写，您使用以下代码
if(password.equals(storedPassword))
这需要您的密码和存储的密码才能完全匹配。
尝试放置一个调试语句并检查数据库实际返回的密码！
答案 1 :(得分：0)
我可能错了，如果不仔细看看DataBaseHelper.class就很难说，但这是我的2美分：我觉得每次重新启动应用程序（重新创建LoginDataBaseAdapter）时都会发生的事情正在重新创建你的数据库，所以首先启动它创建它然后你通过注册并用正确的值填充它，所以这些用于你的以下登录。但是当你离开并重新启动app时，它会重写DB并将其清空。