登录页面不保存用户的详细信息，必须一次又一次登录

Posted 2021-05-05

这是完整的代码。该应用程序工作正常，但我唯一面临问题的是---> 1.当用户第一次注册时，应用程序正常注册，但当我关闭应用程序并打开应用程序时，它仍显示注册窗口显示欢迎窗口。 2.当我登录时，我必须一次又一次地输入详细信息，因为它应该只登录一次..它不应该一次又一次地问。

这些都是问题所在。请有人帮我解决这个问题。

MainActivity代码

public class MainActivity extends AppCompatActivity {
    SQLiteOpenHelper openHelper;
    SQLiteDatabase db;
    Button _btnreg, _btnlogin;
    EditText _txtfname, _txtlname, _txtpass, _txtemail, _txtphone;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        openHelper = new DatabaseHelper(this);
        _txtfname = (EditText)findViewById(R.id.txtfname);
        _txtlname = (EditText)findViewById(R.id.txtlname);
        _txtpass = (EditText)findViewById(R.id.txtpass);
        _txtemail = (EditText)findViewById(R.id.txtemail);
        _txtphone = (EditText)findViewById(R.id.txtphone);
        _btnlogin=(Button)findViewById(R.id.btnlogin);
        _btnreg=(Button)findViewById(R.id.btnreg);
        Log.d("MainActivity","40");


        _btnreg.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d("MainActivity","50");

                db=openHelper.getWritableDatabase();
                String fname=_txtfname.getText().toString();
                String lname=_txtlname.getText().toString();
                String pass=_txtpass.getText().toString();
                String email=_txtemail.getText().toString();
                String phone=_txtphone.getText().toString();
                insertdata(fname, lname,pass,email,phone);
                Toast.makeText(getApplicationContext(), "register successfully",Toast.LENGTH_LONG).show();
                Log.d("MainActivity","60");

            }
        });


        _btnlogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d("MainActivity","70");
                Intent intent = new Intent(MainActivity.this, login.class);
                Log.d("MainActivity","80");
                startActivity(intent);
                Log.d("MainActivity","+90");
            }
        });

    }

    public void insertdata(String fname, String lname, String pass, String email, String phone) {

        Log.d("MainActivity","100");
        ContentValues contentValues = new ContentValues();
        contentValues.put(DatabaseHelper.COL_2, fname);
        contentValues.put(DatabaseHelper.COL_3, lname);
        contentValues.put(DatabaseHelper.COL_4, pass);
        contentValues.put(DatabaseHelper.COL_5, email);
        contentValues.put(DatabaseHelper.COL_6, phone);
        long id = db.insert(DatabaseHelper.TABLE_NAME, null, contentValues);
        Log.d("MainActivity","200");
    }
}

databaseHelper代码

public class DatabaseHelper extends SQLiteOpenHelper {
    public static final String DATABASE_NAME="register.db";
    public static final String TABLE_NAME="registeration";
    public static final String COL_1="ID";
    public static final String COL_2="FirstName";
    public static final String COL_3="LastName";
    public static final String COL_4="Password";
    public static final String COL_5="Email";
    public static final String COL_6="Phone";


    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.d("DatabaseHelper","10");
        db.execSQL("CREATE TABLE " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT,FirstName TEXT,LastName TEXT,Password TEXT,Email TEXT,Phone TEXT)");
        Log.d("DatabaseHelper","20");
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.d("DatabaseHelper","30");
        db.execSQL("DROP TABLE IF EXISTS " +TABLE_NAME);
        Log.d("DatabaseHelper","40");
        onCreate(db);
    }
}

这是登录活动代码

public class login extends AppCompatActivity {
    SQLiteDatabase db;
    SQLiteOpenHelper openHelper;
    Button __btnLogin;
    EditText __txtEmail,__txtPass;
    Cursor cursor;

    public static final String PREFS_NAME = "MyPrefsFile";


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        Log.d("login","11");

        openHelper = new DatabaseHelper(this);
        db=openHelper.getReadableDatabase();
        __btnLogin = (Button)findViewById(R.id.btnLogins);
        __txtEmail = (EditText)findViewById(R.id.txtEmails);
        __txtPass = (EditText)findViewById(R.id.txtPasss);






        Log.d("login","22");

        __btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String email = __txtEmail.getText().toString();
                String pass = __txtPass.getText().toString();




                if (pass == "" || email == "") {

                    Toast.makeText(getApplicationContext(),"No Entry", Toast.LENGTH_LONG).show();

                }



                Log.d("login","33");

                cursor = db.rawQuery("SELECT * FROM "+ DatabaseHelper.TABLE_NAME + " WHERE " + DatabaseHelper.COL_5 + " =? AND " + DatabaseHelper.COL_4 + " =? ", new String[]{email,pass});
                Log.d("login","44");

                if(cursor!=null) {
                    Log.d("login","55");

                    if (cursor.getCount()>0) {
                        Log.d("login","66");
                        //cursor.moveToNext();
                        Log.d("login","77");
                        startActivity(new Intent(login.this, Welcome.class));
                        Toast.makeText(getApplicationContext(), "Login Successfully", Toast.LENGTH_LONG).show();
                    }

                    else {
                        Log.d("login","88");
                        Toast.makeText(getApplicationContext(),"Error", Toast.LENGTH_LONG).show();
                        Log.d("login","99");
                    }
                }



            }
        });
    }
}

谢谢

答案

把boolean放在Pref。在login或register成功之后，

  SharedPreferences pref= PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
    SharedPreferences.Editor editor = pref.edit();
    editor.putBoolean("isLogin", true);
    editor.commit();

在Boolean成功后改变logout旗帜

 SharedPreferences pref= PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor editor = pref.edit();
editor.putBoolean("isLogin", false);
editor.commit();

在condition之前在MainActivity(LAUNCHER Activity)中添加此setContentView

    SharedPreferences pref= PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        if (pref.getBoolean("isLogin", false))
        {
         //Open you Welcome Activity  
 finish();
        }

另一答案

通过使用共享首选项

 SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
                    SharedPreferences.Editor editor = settings.edit();
                    editor.putString("username_preferences", email);
                    editor.putString("password_preferences",password);
                     editor.commit();

另一答案

当用户第一次登录时，将用户数据存储到SharedPreferences中，如密码和用户名。

然后在onCreate（）方法的登录活动之后读取SharedPreferences数据并将if条件放在下面

    if (!TextUtils.isEmpty(password) && !TextUtils.isEmpty(userName)){
        Intent intent=new Intent((this,WelcomeActivity.class));
        startActivity(intent);
    }
    else{

    }