Java 我需要有关阅读SQLite登录电子邮件的帮助
我希望“欢迎活动”中的文本视图能够捕获登录活动中输入的电子邮件 我想为我尝试输入的每个用户检索，现在我只能检索上次注册的用户电子邮件，无论我与其他用户登录，你知道如何做吗 我有一个Java 我需要有关阅读SQLite登录电子邮件的帮助,java,android,database,sqlite,android-studio,Java,Android,Database,Sqlite,Android Studio,我希望“欢迎活动”中的文本视图能够捕获登录活动中输入的电子邮件 我想为我尝试输入的每个用户检索，现在我只能检索上次注册的用户电子邮件，无论我与其他用户登录，你知道如何做吗 我有一个WelcomeActivity和一个SignenActivity，我想做的是WelcomeActivity有一个TextView，我想让TextView从SQLiteHelper读取，当我使用保存在数据库中的电子邮件和密码登录时，它应该读取用于使用SignenActivity登录的选定电子邮件，使用EditText中的
WelcomeActivitySignenActivitypublic class DataBaseHelper extends SQLiteOpenHelper
{
public static final String DB_NAME = "users.dbHelper";
public static final int DB_VERSION = 1;
public static final String TABLE_USERS = "users";
public static final String COLUMN_EMAIL = "email";
public static final String COLUMN_PASSWORD = "password";
public static final String[] ALL_COLUMNS = {COLUMN_EMAIL, COLUMN_PASSWORD};
public DataBaseHelper dbHelper;
public static SQLiteDatabase SQLiteDatabase;
public static final String SQL_CREATE =
"CREATE TABLE IF NOT EXISTS " + TABLE_USERS + " (" +
COLUMN_EMAIL + " STRING PRIMARY KEY, " +
COLUMN_PASSWORD + " STRING);";
public static final String SQL_DROP = "DROP TABLE " + TABLE_USERS;
public DataBaseHelper(@Nullable Context context)
{
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(SQL_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
db.execSQL(SQL_DROP);
onCreate(db);
}
//---opens the database---
public DataBaseHelper open() throws SQLException
{
SQLiteDatabase = this.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
if (SQLiteDatabase != null)
SQLiteDatabase.close();
if (dbHelper != null)
dbHelper.close();
}
// Checking if email exists
public boolean checkEmail(String email)
{
SQLiteDatabase = this.getWritableDatabase();
Cursor cursor = SQLiteDatabase.rawQuery("SELECT * FROM " + TABLE_USERS + " WHERE "
+ COLUMN_EMAIL + " =? ", new String[]{email});
if (cursor.getCount() > 0) return false;
else return true;
}
// Checking the email and password
public boolean checkEmailPassword(String email, String password)
{
SQLiteDatabase = this.getWritableDatabase();
Cursor cursor = SQLiteDatabase.rawQuery("SELECT * FROM " + TABLE_USERS + " WHERE "
+ COLUMN_EMAIL + " =? " + " AND " + COLUMN_PASSWORD + " =? "
, new String[]{email, password});
if (cursor.getCount() > 0) return true;
else return false;
}
public boolean insertEntry(String email, String password)
{
ContentValues newValues = new ContentValues();
// Assign values for each row.
newValues.put("EMAIL", email);
newValues.put("PASSWORD", password);
// Insert the row into your table
long ins = SQLiteDatabase.insert(TABLE_USERS, null, newValues);
///Toast.makeText(context, "Reminder Is Successfully Saved", Toast.LENGTH_LONG).show();
if (ins == -1) return false;
else return true;
}
public int deleteEntry(String email)
{
//String id=String.valueOf(ID);
String where = "EMAIL=?";
int numberOFEntriesDeleted = SQLiteDatabase.delete(TABLE_USERS, where, new String[]{email});
// Toast.makeText(context, "Number fo Entry Deleted Successfully : "+numberOFEntriesDeleted, Toast.LENGTH_LONG).show();
return numberOFEntriesDeleted;
}
public String getSingleEntry(String email)
{
Cursor cursor = SQLiteDatabase.query(TABLE_USERS, null, " EMAIL=?", new String[]{email}, 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 email, String password)
{
// Define the updated row content.
ContentValues updatedValues = new ContentValues();
// Assign values for each row.
updatedValues.put("EMAIL", email);
updatedValues.put("PASSWORD", password);
String where = "EMAIL = ?";
SQLiteDatabase.update(TABLE_USERS, updatedValues, where, new String[]{email});
}
public String getUsername(String COLUMN_EMAIL) throws SQLException
{
String email = "No Email Found";
SQLiteDatabase = this.getReadableDatabase();
Cursor cursor = SQLiteDatabase.query(TABLE_USERS, new String[]{COLUMN_EMAIL}, null, null,
null, null, null);
if (cursor.moveToNext()) {
cursor.moveToNext();
cursor.moveToLast();
email = cursor.getString(cursor.getColumnIndex(COLUMN_EMAIL));
}
cursor.close();
return email;
}
public class WelcomeActivity extends AppCompatActivity
{
private static int SPLASH_TIME_OUT = 4000;
private SQLiteDatabase m_db;
private TextView tvEmails;
DataBaseHelper db = new DataBaseHelper(this);
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_welcome);
db = new DataBaseHelper(this);
try {
db = db.open();
} catch (android.database.SQLException e) {
e.printStackTrace();
}
TextView tvEmail = (TextView) findViewById(R.id.tvEmails);
// Bundle bundle;
// bundle = getIntent().getExtras();
// tvEmail.setText(bundle.getString(""));
String email = db.getUsername(DataBaseHelper.COLUMN_EMAIL);
tvEmail.setText(email);
new Handler().postDelayed(new Runnable()
{
@Override
public void run()
{
Intent intent = new Intent(WelcomeActivity.this, EthicsActivity.class);
startActivity(intent);
finish();
}
}, SPLASH_TIME_OUT);
}
}
public class LoginActivity extends AppCompatActivity
{
public static final String PREFS = "global_prefs";// UI References
public static final String KEY_EMAIL = "email";
private DataBaseHelper db;
private EditText etEmail, etPassword;
private Button btnSignIn;
private TextView tvRegisterClick;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
final EditText etEmail = findViewById(R.id.etEmail);
final EditText etPassword = findViewById(R.id.etPassword);
Button btnSignIn = findViewById(R.id.btnSignIn);
TextView tvRegisterClick = findViewById(R.id.tvRegisterClick);
db = new DataBaseHelper(this);
tvRegisterClick.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
Intent intent = new Intent(LoginActivity.this, MainActivity.class);
startActivity(intent);
}
});
btnSignIn.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
// Store values at the same time of the login attempt
String email = etEmail.getText().toString();
String password = etPassword.getText().toString();
boolean checkEmailPassword = db.checkEmailPassword(email, password);
if (checkEmailPassword) {
Toast.makeText(getApplicationContext(), "login successfully!", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(LoginActivity.this, WelcomeActivity.class);
intent.putExtra("", email);
startActivity(intent);
} else {
if (!checkEmailPassword)
Toast.makeText(getApplicationContext(), "Wrong email or password", Toast.LENGTH_SHORT).show();
}
//// Reset Errors
// etEmail.setError(null);
// etPassword.setError(null);
//
// boolean errorOccured = false;
// View focusView = null;
//
// // Check for a valid password if the user entered one
// if(!isPasswordValid(password))
// {
// etPassword.setError("Invalid password");
// focusView = etPassword;
// errorOccured = true;
// }
//
// // Check for a valid email, if the user enters one
// if(!isEmailValid(email))
// {
// etEmail.setError("Invalid Email");
// focusView = etEmail;
// errorOccured = true;
// }
//
// if(errorOccured)
// {
// focusView.requestFocus();
// }
// else
// {
// SharedPreferences.Editor editor = getSharedPreferences(PREFS, MODE_PRIVATE).edit();
//
// editor.putString(KEY_EMAIL, email);
// editor.apply();
//
// finish();
// }
}
// private boolean isEmailValid(String email)
// {
// return email.contains("");
// }
//
// private boolean isPasswordValid(String password)
// {
// return password.length() > 4;
// }
});
}
}
public class DataBaseHelper extends SQLiteOpenHelper
{
public static final String DB_NAME = "users.dbHelper";
public static final int DB_VERSION = 1;
public static final String TABLE_USERS = "users";
public static final String COLUMN_EMAIL = "email";
public static final String COLUMN_PASSWORD = "password";
public static final String[] ALL_COLUMNS = {COLUMN_EMAIL, COLUMN_PASSWORD};
public DataBaseHelper dbHelper;
public static SQLiteDatabase SQLiteDatabase;
public static final String SQL_CREATE =
"CREATE TABLE IF NOT EXISTS " + TABLE_USERS + " (" +
COLUMN_EMAIL + " STRING PRIMARY KEY, " +
COLUMN_PASSWORD + " STRING);";
public static final String SQL_DROP = "DROP TABLE " + TABLE_USERS;
public DataBaseHelper(@Nullable Context context)
{
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(SQL_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
db.execSQL(SQL_DROP);
onCreate(db);
}
//---opens the database---
public DataBaseHelper open() throws SQLException
{
SQLiteDatabase = this.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
if (SQLiteDatabase != null)
SQLiteDatabase.close();
if (dbHelper != null)
dbHelper.close();
}
// Checking if email exists
public boolean checkEmail(String email)
{
SQLiteDatabase = this.getWritableDatabase();
Cursor cursor = SQLiteDatabase.rawQuery("SELECT * FROM " + TABLE_USERS + " WHERE "
+ COLUMN_EMAIL + " =? ", new String[]{email});
if (cursor.getCount() > 0) return false;
else return true;
}
// Checking the email and password
public boolean checkEmailPassword(String email, String password)
{
SQLiteDatabase = this.getWritableDatabase();
Cursor cursor = SQLiteDatabase.rawQuery("SELECT * FROM " + TABLE_USERS + " WHERE "
+ COLUMN_EMAIL + " =? " + " AND " + COLUMN_PASSWORD + " =? "
, new String[]{email, password});
if (cursor.getCount() > 0) return true;
else return false;
}
public boolean insertEntry(String email, String password)
{
ContentValues newValues = new ContentValues();
// Assign values for each row.
newValues.put("EMAIL", email);
newValues.put("PASSWORD", password);
// Insert the row into your table
long ins = SQLiteDatabase.insert(TABLE_USERS, null, newValues);
///Toast.makeText(context, "Reminder Is Successfully Saved", Toast.LENGTH_LONG).show();
if (ins == -1) return false;
else return true;
}
public int deleteEntry(String email)
{
//String id=String.valueOf(ID);
String where = "EMAIL=?";
int numberOFEntriesDeleted = SQLiteDatabase.delete(TABLE_USERS, where, new String[]{email});
// Toast.makeText(context, "Number fo Entry Deleted Successfully : "+numberOFEntriesDeleted, Toast.LENGTH_LONG).show();
return numberOFEntriesDeleted;
}
public String getSingleEntry(String email)
{
Cursor cursor = SQLiteDatabase.query(TABLE_USERS, null, " EMAIL=?", new String[]{email}, 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 email, String password)
{
// Define the updated row content.
ContentValues updatedValues = new ContentValues();
// Assign values for each row.
updatedValues.put("EMAIL", email);
updatedValues.put("PASSWORD", password);
String where = "EMAIL = ?";
SQLiteDatabase.update(TABLE_USERS, updatedValues, where, new String[]{email});
}
public String getUsername(String COLUMN_EMAIL) throws SQLException
{
String email = "No Email Found";
SQLiteDatabase = this.getReadableDatabase();
Cursor cursor = SQLiteDatabase.query(TABLE_USERS, new String[]{COLUMN_EMAIL}, null, null,
null, null, null);
if (cursor.moveToNext()) {
cursor.moveToNext();
cursor.moveToLast();
email = cursor.getString(cursor.getColumnIndex(COLUMN_EMAIL));
}
cursor.close();
return email;
}
public class WelcomeActivity extends AppCompatActivity
{
private static int SPLASH_TIME_OUT = 4000;
private SQLiteDatabase m_db;
private TextView tvEmails;
DataBaseHelper db = new DataBaseHelper(this);
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_welcome);
db = new DataBaseHelper(this);
try {
db = db.open();
} catch (android.database.SQLException e) {
e.printStackTrace();
}
TextView tvEmail = (TextView) findViewById(R.id.tvEmails);
// Bundle bundle;
// bundle = getIntent().getExtras();
// tvEmail.setText(bundle.getString(""));
String email = db.getUsername(DataBaseHelper.COLUMN_EMAIL);
tvEmail.setText(email);
new Handler().postDelayed(new Runnable()
{
@Override
public void run()
{
Intent intent = new Intent(WelcomeActivity.this, EthicsActivity.class);
startActivity(intent);
finish();
}
}, SPLASH_TIME_OUT);
}
}
public class LoginActivity extends AppCompatActivity
{
public static final String PREFS = "global_prefs";// UI References
public static final String KEY_EMAIL = "email";
private DataBaseHelper db;
private EditText etEmail, etPassword;
private Button btnSignIn;
private TextView tvRegisterClick;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
final EditText etEmail = findViewById(R.id.etEmail);
final EditText etPassword = findViewById(R.id.etPassword);
Button btnSignIn = findViewById(R.id.btnSignIn);
TextView tvRegisterClick = findViewById(R.id.tvRegisterClick);
db = new DataBaseHelper(this);
tvRegisterClick.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
Intent intent = new Intent(LoginActivity.this, MainActivity.class);
startActivity(intent);
}
});
btnSignIn.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
// Store values at the same time of the login attempt
String email = etEmail.getText().toString();
String password = etPassword.getText().toString();
boolean checkEmailPassword = db.checkEmailPassword(email, password);
if (checkEmailPassword) {
Toast.makeText(getApplicationContext(), "login successfully!", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(LoginActivity.this, WelcomeActivity.class);
intent.putExtra("", email);
startActivity(intent);
} else {
if (!checkEmailPassword)
Toast.makeText(getApplicationContext(), "Wrong email or password", Toast.LENGTH_SHORT).show();
}
//// Reset Errors
// etEmail.setError(null);
// etPassword.setError(null);
//
// boolean errorOccured = false;
// View focusView = null;
//
// // Check for a valid password if the user entered one
// if(!isPasswordValid(password))
// {
// etPassword.setError("Invalid password");
// focusView = etPassword;
// errorOccured = true;
// }
//
// // Check for a valid email, if the user enters one
// if(!isEmailValid(email))
// {
// etEmail.setError("Invalid Email");
// focusView = etEmail;
// errorOccured = true;
// }
//
// if(errorOccured)
// {
// focusView.requestFocus();
// }
// else
// {
// SharedPreferences.Editor editor = getSharedPreferences(PREFS, MODE_PRIVATE).edit();
//
// editor.putString(KEY_EMAIL, email);
// editor.apply();
//
// finish();
// }
}
// private boolean isEmailValid(String email)
// {
// return email.contains("");
// }
//
// private boolean isPasswordValid(String password)
// {
// return password.length() > 4;
// }
});
}
}
由于您在开始WelcomeActivity之前已成功登录，因此无需根据从数据库收到的电子邮件从数据库中获取电子邮件（这听起来很愚蠢/无用）。但是，您需要做的是将电子邮件从登录活动传递到欢迎活动。这就是你的问题所在 您遇到的第一个问题是使用
intent.putExtra（“，email”）没有有用的标识符，无法在尝试提取时确定额外的代码。相反，您应该使用（密钥\电子邮件存在）：-
intent.putExtra（密钥电子邮件、电子邮件）//