当我重新打开应用 android studio 时如何让用户保持登录状态

Question

我制作了应用程序并使用 sqlite 数据库将详细信息存储在数据库中。但是现在我想验证并保持用户登录状态，如果用户直接登录，那么接下来应该打开 activity。谁能帮我一下。

这是登录 activity:

     private TextInputEditText mobileedittext,passwordedittext;
private DBase dBase;
private User user;

public static String PREFS = "prefsFile";
Button b1;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    initview();
    initListener();
    initObject();

}

private void initview(){
    layout = findViewById(R.id.login_layout);

    lay_login_mobile = findViewById(R.id.lay_login_mobile);
    lay_login_password = findViewById(R.id.lay_login_password);

    mobileedittext = findViewById(R.id.loginmobile_edit);
    passwordedittext = findViewById(R.id.loginpassword_edit);

    b1 = findViewById(R.id.Loginbtn);

}

private void initListener(){
    b1.setOnClickListener(v -> {


        String mob = mobileedittext.getText().toString();
        String pass = passwordedittext.getText().toString();
        if(mob.equals("") || pass.equals("")){
            Toast.makeText(Login.this, "Enter all the fields", Toast.LENGTH_SHORT).show();

        } else {
            if(!dBase.checkUser(mobileedittext.getText().toString(),passwordedittext.getText().toString())) {
                Toast.makeText(Login.this, "Invalid Credentials. Check Mobile number or Password", Toast.LENGTH_LONG).show();
            }
            else {
                Toast.makeText(Login.this, "Login Successful", Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(Login.this, BabyDetails.class);
                startActivity(intent);
            }
        }
        SharedPreferences sharedPreferences = getSharedPreferences(Login.PREFS,0);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putBoolean("hasLoggedIn",true);
        editor.commit();
    });
}

private void initObject(){
    dBase = new DBase(Login.this);
    user = new User();
}

主要 Activity（启动画面）：

  ProgressBar pb;
Handler h = new Handler();
int count = 0;
Timer timer;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);



    pb = (ProgressBar) findViewById(R.id.progressBar);

    timer = new Timer();
    TimerTask timerTask = new TimerTask() {
        @Override
        public void run() {
            count++;
            pb.setProgress(count);
            if(count == 99){
                h.postDelayed(new Runnable() {
                    @Override
                    public void run() {

                        SharedPreferences sharedPreferences = getSharedPreferences(Login.PREFS,0);
                        Boolean hasLoggedIn = sharedPreferences.getBoolean("hasLoggedIn",false);

                        if(hasLoggedIn){
                            Intent intent = new Intent(MainPage.this,BabyDetails.class);
                            startActivity(intent);
                            finish();
                        }
                        else {
                            Intent i = new Intent(MainPage.this, Login.class);
                            startActivity(i);
                            finish();
                        }


                    }
                },100);


            }
        }
    };
    timer.schedule(timerTask,0,100);

数据库包含 checkuser 函数，它检查用户是否已经存在，但现在它还应该检查用户是否已登录：

        private static final String DATABASE_NAME = "UserDetails.db";
private static final String TABLE_USER = "User";
private static final String COLUMN_USER_ID = "user_id";
private static final String COLUMN_USER_MOBILE = "mobile";
private static final String COLUMN_USER_EMAIL = "email";
private static final String COLUMN_USER_MOTHERNAME = "mother_name";
private static final String COLUMN_USER_FATHERNAME = "father_name";
private static final String COLUMN_USER_PASSWORD = "password";
private static final String COLUMN_USER_CONFIRM_PASSWORD = "confirm_password";


private String CREATE_USER_TABLE = "CREATE TABLE  "+ TABLE_USER + "(" +
        COLUMN_USER_ID +" INTEGER PRIMARY KEY AUTOINCREMENT , " + COLUMN_USER_MOBILE + " TEXT," + COLUMN_USER_EMAIL + " TEXT, "
        + COLUMN_USER_MOTHERNAME + " TEXT, " + COLUMN_USER_FATHERNAME + " TEXT, " +
        COLUMN_USER_PASSWORD + " TEXT, " + COLUMN_USER_CONFIRM_PASSWORD + " TEXT " + ")";




private String DROP_USER_TABLE = "DROP TABLE IF EXISTS " + TABLE_USER;

public DBase(Context context){
    super(context,DATABASE_NAME,null,DATABASE_VERSION);

}




@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(CREATE_USER_TABLE);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
     db.execSQL(DROP_USER_TABLE);
    onCreate(db);
}

public void addUser(User user){
    SQLiteDatabase db= this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(COLUMN_USER_MOBILE,user.getMobile());
    values.put(COLUMN_USER_EMAIL,user.getEmail());
    values.put(COLUMN_USER_MOTHERNAME,user.getMothername());
    values.put(COLUMN_USER_FATHERNAME,user.getFathername());
    values.put(COLUMN_USER_PASSWORD,user.getPass());
    values.put(COLUMN_USER_CONFIRM_PASSWORD,user.getConpass());
    db.insert(TABLE_USER,null,values);
    db.close();
}
 public boolean checkUser(String mobile, String pass ){

    String[] column = {COLUMN_USER_ID};
    SQLiteDatabase db= this.getReadableDatabase();
    String selection = COLUMN_USER_MOBILE+ " = ? " + " AND " + COLUMN_USER_PASSWORD + " = ? ";
    String[] selectionArgs = {mobile, pass};

    int cursorCount;
    try (Cursor cursor = db.query(TABLE_USER, column, selection, selectionArgs, null, null, null)) {
        cursorCount = cursor.getCount();
    }
    db.close();
    if(cursorCount > 0){
        return true;
    }

    return false;
}

谁能提供必要的代码并解释一下。

谢谢

Answer 1

登录 LoginActivity 时只需设置 SharedPreference

   public static final String MyPREFERENCES = "MyPrefs" ;
   public static final String Name = "nameKey";

在 OnCreate() 中

SharedPreferences.Editor editor = sharedpreferences.edit();
editor.putString(Name, n);
editor.commit();

并且在 MainActivity

  SharedPreferences sharedpreferences = getSharedPreferences(MainActivity.MyPREFERENCES, Context.MODE_PRIVATE);
  SharedPreferences.Editor editor = sharedpreferences.edit();
  editor.clear();
  editor.commit();

当我重新打开应用 android studio 时如何让用户保持登录状态

How can I keep the user logged in when I reopens the app android studio

android

sqlite

android-studio

sqliteopenhelper