知识养成了思想,思想同时又在融化知识。这篇文章主要讲述Android SQLite用户登录不起作用相关的知识，希望能为你提供帮助。
我实际上在我的应用程序中实现了一个SQLite数据库并进行了一个Login活动。因此，当应用程序启动时，我启动我的登录活动，并在那里我访问数据库。因此，用户输入名称和密码并按“anmelden”，然后数据库检查用户是否已经存在，如果是，则密码是否正确，如果正确，则活动结束，用户可以继续。如果密码不正确但用户存在，则不会发生任何事情，并且将显示Toast。如果没有给出Name的用户，则将使用该Password和Name创建一个新用户。
我的问题是，当我创建一个新用户时，一切似乎工作正常，但如果我重新启动应用程序并尝试使用相同的数据登录，它仍然会创建一个新用户。
我遗憾地不知道这在数据库中看起来怎么样因为我没有root电话atm，所以我希望你们能帮助我，因为我没有发现错误
这是我的“Anmeldung”（登录）课程
public class Anmeldung extends Activity {
public Datasource datasource = new Datasource(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_anmeldung);
}//// OnClick-Methoden/// public void anmelden(View view) {//the Login methodEditText t = (EditText) findViewById(R.id.editText_username);
String name = t.getText().toString();
EditText e = (EditText) findViewById(R.id.editText_passwort);
String psswd = e.getText().toString();
datasource.open();
if (datasource.UserExists(name)) {
if (datasource.correctPassword(name, psswd)) {
datasource.close();
finish();
} else {
@SuppressLint("WrongConstant") Toast toast = Toast.makeText(getApplicationContext(), "Falsches Passwort", 3);
toast.show();
}
} else {
datasource.createUser(name, psswd, 0, 0);
@SuppressLint("WrongConstant") Toast toast = Toast.makeText(getApplicationContext(), "Neuen Nutzer erstellt", 3);
toast.show();
finish();
}}
}
这是我的数据源类，包含所有相关方法
public class Datasource {
//Log-Tag
private static final String LOG_TAG = Datasource.class.getSimpleName();
//Datenbankspezifische Variablen
private SQLiteDatabase database;
private Datahelper dbHelper;
private String[] columns = {Datahelper.COLUMN_ID, Datahelper.COLUMN_TYPE, Datahelper.COLUMN_NAME, Datahelper.COLUMN_EXPIRATION, Datahelper.COLUMN_OWNER};
private String[] columns_users = {Datahelper.COLUMN_ID_USERS, Datahelper.COLUMN_NAME_USERS, Datahelper.COLUMN_PSSWD_USERS, Datahelper.COLUMN_SOAP_USERS, Datahelper.COLUMN_EP_USERS};
private String[] column_id_user = {Datahelper.COLUMN_ID_USERS};
private String[] column_name_user = {Datahelper.COLUMN_NAME_USERS};
private String[] column_psswd_user = {Datahelper.COLUMN_PSSWD_USERS};
//Konstruktor
public Datasource(Context context) {
Log.d(LOG_TAG, "DataSource is now creating the dbHelper");
dbHelper = new Datahelper(context);
}//?ffnen der Datenbank
public void open() {
Log.d(LOG_TAG, "asking for reference");
database = dbHelper.getWritableDatabase();
Log.d(LOG_TAG, "received reference. path: " + database.getPath());
}//Schlie?en der Datenbank
public void close() {
dbHelper.close();
Log.d(LOG_TAG, "closed database");
}public User createUser(String name, String psswd, long soap, long ep) {
ContentValues c = new ContentValues();
c.put(Datahelper.COLUMN_NAME_USERS, name);
c.put(Datahelper.COLUMN_PSSWD_USERS, psswd);
c.put(Datahelper.COLUMN_SOAP_USERS, soap);
c.put(Datahelper.COLUMN_EP_USERS, ep);
long insId = database.insert(Datahelper.TABLE_USERS, null, c);
Cursor cursor = database.query(Datahelper.TABLE_USERS, columns_users, Datahelper.COLUMN_ID_USERS + "=" + insId, null, null, null, null);
cursor.moveToLast();
return cursorToUser(cursor);
}private User cursorToUser(Cursor cursor) {int idId = cursor.getColumnIndex(Datahelper.COLUMN_ID_USERS);
int idName = cursor.getColumnIndex(Datahelper.COLUMN_NAME_USERS);
int idPsswd = cursor.getColumnIndex(Datahelper.COLUMN_PSSWD_USERS);
int idSoap = cursor.getColumnIndex(Datahelper.COLUMN_SOAP_USERS);
int idEp = cursor.getColumnIndex(Datahelper.COLUMN_EP_USERS);
long id = cursor.getLong(idId);
String name = cursor.getString(idName);
String psswd = cursor.getString(idPsswd);
long soap = cursor.getLong(idSoap);
long ep = cursor.getLong(idEp);
return new User(id, name, psswd, soap, ep);
}public boolean UserExists(String name) {
try {
Cursor cursor = database.query(Datahelper.TABLE_USERS, column_id_user, Datahelper.COLUMN_NAME_USERS + " = " + name, null, null, null, null);
long id = cursor.getLong(cursor.getColumnIndex(Datahelper.COLUMN_ID_USERS));
cursor = database.query(Datahelper.TABLE_USERS, column_name_user, Datahelper.COLUMN_ID_USERS + " = " + id, null, null, null, null);
String n = cursor.getString(cursor.getColumnIndex(Datahelper.COLUMN_NAME_USERS));
return true;
} catch (Exception e) {
}
return false;
}public boolean correctPassword(String name, String psswd) {
try {Cursor cursor = database.query(Datahelper.TABLE_USERS, column_id_user, Datahelper.COLUMN_NAME_USERS + " = " + name, null, null, null, null);
long id = cursor.getLong(cursor.getColumnIndex(Datahelper.COLUMN_ID_USERS));
cursor = database.query(Datahelper.TABLE_USERS, column_name_user, Datahelper.COLUMN_ID_USERS + " = " + id, null, null, null, null);
String n = cursor.getString(cursor.getColumnIndex(Datahelper.COLUMN_NAME_USERS));
cursor = database.query(Datahelper.TABLE_USERS, column_psswd_user, Datahelper.COLUMN_ID_USERS + " = " + id, null, null, null, null);
String p = cursor.getString(cursor.getColumnIndex(Datahelper.COLUMN_PSSWD_USERS));
if (n == name &
&
psswd == p) return true;
} catch (Exception e) {
}
return false;
}
}
希望你能帮助我，告诉你是否需要别的东西:)
日志：
12-20 20:33:56.684 24009-24009/com.ein_siedler.putzplaner D/Datasource: asking for reference
12-20 20:33:56.689 24009-24009/com.ein_siedler.putzplaner D/Datasource: received reference. path: /data/user/0/com.ein_siedler.putzplaner/databases/task_list.db
12-20 20:33:56.690 24009-24009/com.ein_siedler.putzplaner E/SQLiteLog: (1) no such column: Test
12-20 20:33:56.696 24009-24009/com.ein_siedler.putzplaner W/System.err: android.database.sqlite.SQLiteException: no such column: Test (code 1): , while compiling: SELECT _id FROM table_users WHERE name = Test
12-20 20:33:56.696 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
12-20 20:33:56.696 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
12-20 20:33:56.696 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
12-20 20:33:56.696 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
12-20 20:33:56.696 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteProgram.<
init>
(SQLiteProgram.java:58)
12-20 20:33:56.697 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteQuery.<
init>
(SQLiteQuery.java:37)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1328)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1175)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1046)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1214)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at com.ein_siedler.putzplaner.Datasource.UserExists(Datasource.java:139)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at com.ein_siedler.putzplaner.activities.Anmeldung.anmelden(Anmeldung.java:50)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at java.lang.reflect.Method.invoke(Native Method)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.view.View$DeclaredOnClickListener.onClick(View.java:4463)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.view.View.performClick(View.java:5233)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.view.View$PerformClick.run(View.java:21211)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.os.Handler.handleCallback(Handler.java:739)
12-20 20:33:56.698 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.os.Handler.dispatchMessage(Handler.java:95)
12-20 20:33:56.699 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.os.Looper.loop(Looper.java:148)
12-20 20:33:56.699 24009-24009/com.ein_siedler.putzplaner W/System.err:at android.app.ActivityThread.main(ActivityThread.java:5539)
12-20 20:33:56.699 24009-24009/com.ein_siedler.putzplaner W/System.err:at java.lang.reflect.Method.invoke(Native Method)
12-20 20:33:56.699 24009-24009/com.ein_siedler.putzplaner W/System.err:at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
12-20 20:33:56.699 24009-24009/com.ein_siedler.putzplaner W/System.err:at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
12-20 20:33:56.743 24009-24009/com.ein_siedler.putzplaner D/AppTracker: App Event: stop
12-20 20:33:56.795 24009-24009/com.ein_siedler.putzplaner D/AppTracker: App Event: start
12-20 20:33:56.872 24009-24009/com.ein_siedler.putzplaner D/AbstractTracker: Event success
12-20 20:33:56.878 24009-24009/com.ein_siedler.putzplaner D/AbstractTracker: Event success
12-20 20:33:56.955 24009-24146/com.ein_siedler.putzplaner D/OpenGLRenderer: endAllStagingAnimators on 0xb35ec380 (RippleDrawable) with handle 0x9f07c660
DatahHelper类：
class Datahelper extends SQLiteOpenHelper {
//Strings für Datenbank
public static final String DB_NAME = "task_list.db";
public static final int DB_VERSION = 1;
public static final String TABLE_TASK_LIST = "task_list";
public static final String COLUMN_ID = "_id";
public static final String COLUMN_TYPE = "type";
public static final String COLUMN_NAME = "name";
public static final String COLUMN_EXPIRATION = "expiration";
public static final String COLUMN_OWNER = "owner";
public static final String SQL_CREATE = "CREATE TABLE " + TABLE_TASK_LIST + "(" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COLUMN_TYPE + " TEXT NOT NULL, " + COLUMN_NAME + " TEXT NOT NULL, " + COLUMN_EXPIRATION + " TEXT NOT NULL, " + COLUMN_OWNER + " TEXT NOT NULL);
";
public static final String TABLE_USERS = "table_users";
public static final String COLUMN_ID_USERS = "_id";
public static final String COLUMN_NAME_USERS = "name";
public static final String COLUMN_PSSWD_USERS = "psswd";
public static final String COLUMN_SOAP_USERS = "soap";
public static final String COLUMN_EP_USERS = "ep";
public static final String SQL_CREATE_USERS = "CREATE TABLE " + TABLE_USERS + "(" + COLUMN_ID_USERS + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COLUMN_NAME_USERS + " TEXT NOT NULL, " + COLUMN_PSSWD_USERS + " TEXT NOT NULL, " + COLUMN_SOAP_USERS + " INTEGER, " + COLUMN_EP_USERS + " INTEGER);
";
private static final String LOG_TAG = Datahelper.class.getSimpleName();
public Datahelper(Context context) {
//Konstruktor
super(context, DB_NAME, null, DB_VERSION);
Log.d(LOG_TAG, "Succesfully created database: " + getDatabaseName());
}//Erstellen einer neuen Datenbank
@Override
public void onCreate(SQLiteDatabase db) {
try {Log.d(LOG_TAG, "creating table " + SQL_CREATE);
db.execSQL(SQL_CREATE);
db.execSQL(SQL_CREATE_USERS);
} catch (Exception ex) {
Log.d(LOG_TAG, "Error while creating table: " + ex.getMessage());
}}//?nderung an Struktur
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {}
}
【Android SQLite用户登录不起作用】更改代码后的错误日志，但我不知道如何格式化
12-21 07:53:25.097 22705-22705/com.ein_siedler.putzplaner W/System.err:android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 0
12-21 07:53:25.098 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.database.AbstractCursor.checkPosition(AbstractCursor.java:460)
12-21 07:53:25.098 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136)
12-21 07:53:25.098 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.database.AbstractWindowedCursor.getLong(AbstractWindowedCursor.java:74)
12-21 07:53:25.099 22705-22705/com.ein_siedler.putzplaner W/System.err:at com.ein_siedler.putzplaner.Datasource.UserExists(Datasource.java:141)
12-21 07:53:25.099 22705-22705/com.ein_siedler.putzplaner W/System.err:at com.ein_siedler.putzplaner.activities.Anmeldung.anmelden(Anmeldung.java:47)
12-21 07:53:25.099 22705-22705/com.ein_siedler.putzplaner W/System.err:at java.lang.reflect.Method.invoke(Native Method)
12-21 07:53:25.099 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.view.View$DeclaredOnClickListener.onClick(View.java:4463)
12-21 07:53:25.099 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.view.View.performClick(View.java:5233)
12-21 07:53:25.099 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.view.View$PerformClick.run(View.java:21211)
12-21 07:53:25.100 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.os.Handler.handleCallback(Handler.java:739)
12-21 07:53:25.100 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.os.Handler.dispatchMessage(Handler.java:95)
12-21 07:53:25.100 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.os.Looper.loop(Looper.java:148)
12-21 07:53:25.100 22705-22705/com.ein_siedler.putzplaner W/System.err:at android.app.ActivityThread.main(ActivityThread.java:5539)
12-21 07:53:25.100 22705-22705/com.ein_siedler.putzplaner W/System.err:at java.lang.reflect.Method.invoke(Native Method)
12-21 07:53:25.100 22705-22705/com.ein_siedler.putzplaner W/System.err:at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
12-21 07:53:25.100 22705-22705/com.ein_siedler.putzplaner W/System.err:at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
答案我认为你的
Datasource类中出现了问题，你的UserExists函数返回false;
你不能看到任何错误，因为你在每个try-catch的catch异常部分错过了e.printStackTrace();
尝试将e.printStackTrace();
设置为datasource类中的每个try-catch并重建app并运行它。在那里展示Catlog ......更新：
试试这个功能：
public boolean UserExists(String name) {
try {
Cursor cursor = database.query(Datahelper.TABLE_USERS, null, Datahelper.COLUMN_NAME_USERS + " = '" + name + "'", null, null, null, null);
String n = cursor.getString(cursor.getColumnIndex(Datahelper.COLUMN_NAME_USERS));
return true;
} catch (Exception e) {
e.printStackTrace();
}
return false;
}
如果在sql查询中使用字符串值，则检查两次它必须在''之间
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