如何在 Android（MVVM、数据绑定、Kotlin）中实现“记住我”function？

Question

• I want to implement a "Remember me" function in AuthActivity

• The way it must work is that when I enter correct user information it is going to be stored in SharedPreferences.

• So the next time I enter the app I must be in the next activity SelectWorkActivity, however if I want to go back to AuthActivity editTexts(inputs in AuthActivity) must have stored user information.

• The structure of the app must follow the MVVM pattern no matter what

• Ask me any question you need.

• Pictures are provided down below as well as the code below the pictures.

• Thank you so much ahead if you contribute to the future solution of this problem.

AuthActivity(Authentication)

SelectWorkActivity(Just the next page)

AuthActivity()

class AuthActivity : AppCompatActivity(), AuthListener {
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    val API = API()
    val Pref = PreferenceProvider(this)
    val repository = UserRepository(API, Pref)
    val factory = AuthViewModelFactory(repository)

    // Getting data from UI

    val binding: ActivityAuthBinding = DataBindingUtil.setContentView(this, R.layout.activity_auth)
    val viewModel = ViewModelProviders.of(this, factory).get(AuthViewModel::class.java)
    binding.authViewModel = viewModel

    //

    viewModel.authListener = this
    viewModel.onActivated()


}

override fun onStarted() {
    toast("Аутентификация в процессе...")


}

override fun onSuccess(user: ValueAuth) {
    toast("Работник ${user.fio} вошел в систему")
}

override fun onFailure(message: String) {
    toast(message)
}

override fun navigateToSelectWork() {

    val nav = Intent(applicationContext, SelectWorkActivity::class.java)
    startActivity(nav)

}

override fun errorLogin(errorMessage: String) {
    login_input.error = errorMessage
    refocusError(login_input)
}

override fun errorPassword(errorMessage: String) {
    password_input.error = errorMessage
    refocusError(password_input)
}



private fun refocusError(componentToFocus: View) {
    if(componentToFocus.requestFocus()){
        window.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE)
    }

}

override fun onActivate(info: SharePrefData) {
    super.onResume()
    val (login, password, checked) = info
    login_input.setText(login)
    password_input.setText(password)
    checkBox.isChecked = checked

}

}

AuthListener()

interface AuthListener {

fun onStarted()
fun onSuccess(user: ValueAuth)
fun onFailure(message: String)
fun navigateToSelectWork()
fun errorLogin(errorMessage: String)
fun errorPassword(errorMessage: String)
fun onActivate(info: SharePrefData)

}

AuthViewModel()

class AuthViewModel(
private val repository: UserRepository

): ViewModel() {

var email: String? = null
var password: String? = null
var authListener: AuthListener? = null
var onChecked: Boolean? = false







fun onActivated (){


    var onChecked: Boolean = repository.getBoolean()
    if(onChecked == true){


        authListener?.onActivate(repository.getInfo())

        authIn()
    } else {
        authListener?.onFailure("Введите ваши данные")
    }

}

fun onCheckedClick(view: View){
    onChecked = true
}

fun authIn(){

    authListener?.onStarted()

    Coroutines.main {


        try {
            val authResponse = repository.userAuth(email!!, password!!)



            authResponse.value?.let {
                repository.saveAuth(email!!, password!!, onChecked!!)
                authListener?.navigateToSelectWork()
                authListener?.onSuccess(it)


                return@main
            }
            authListener?.onFailure("Ошибка: ${authResponse.result!!.errMsg}")

        } catch (error: APIException){
            authListener?.onFailure(error.message!!)
        }
    }

}


fun onLoginButtonClicked(view: View) {

    if(email.isNullOrEmpty())
    {
        authListener?.errorLogin("Заполните ваш логин")
        false

    }
    else if(password.isNullOrEmpty())
    {
        authListener?.errorPassword("Заполните ваш пароль")
        false

    }
    else
    {
        authIn()
    }
    
}

}

UserRepository()

class  UserRepository(
private val API: API,
private val Preference: PreferenceProvider

): SaveAPIRequest() {

 suspend fun userAuth(email: String, password: String): AuthResponse {

         return APIRequest { API.userAuth(email, password) }

}

fun saveAuth(email: String, password: String, checked: Boolean){
    Preference.saveLastSavedAuth(email, password, checked)

}


fun getBoolean(): Boolean
{
    return Preference.getBoolean()
}

fun getInfo(): SharePrefData
{
    return Preference.getInfo()
}

}

PreferenceProvider()

private const val LOGIN_SAVED = "KEY_TO_LOGIN_SAVED"

private const val PASSWORD_SAVED = "KEY_TO_PASSWORD_SAVED" private const val CHECKED = "KEY_TO_CHECKED_SAVED"

class PreferenceProvider( context: Context ){ private var appContext = context.applicationContext private val preference: SharedPreferences get() = PreferenceManager.getDefaultSharedPreferences(appContext)

fun saveLastSavedAuth(savedLogin: String, savedPassword: String, savedChecked: Boolean){
    preference.edit().putString(LOGIN_SAVED, savedLogin).apply()
    preference.edit().putString(PASSWORD_SAVED, savedPassword).apply()
    preference.edit().putBoolean(CHECKED, savedChecked).apply()
}

fun getBoolean(): Boolean{
    return preference.getBoolean(CHECKED, false)
}

fun getInfo(): SharePrefData {

    val login = preference.getString(LOGIN_SAVED, "")
    val password = preference.getString(PASSWORD_SAVED, "")
    val checked = preference.getBoolean(CHECKED, false)

    return SharePrefData(login, password, checked)

}

fun doNotSaveLastSavedAuth(){

    preference.edit().putString(LOGIN_SAVED, "").apply()
    preference.edit().putString(PASSWORD_SAVED, "").apply()
    preference.edit().putBoolean(CHECKED, false).apply()
}

}

Answer 1

• I want to implement a "Remember me" function in AuthActivity

• The way it must work is that when I enter correct user information it is going to be stored in SharedPreferences.

• So the next time I enter the app I must be in the next activity SelectWorkActivity, however if I want to go back to AuthActivity editTexts(inputs in AuthActivity) must have stored user information.

• The structure of the app must follow the MVVM pattern no matter what

• Ask me any question you need.

• Pictures are provided down below as well as the code below the pictures.

• Thank you so much ahead if you contribute to the future solution of this problem.

AuthActivity(Authentication)

SelectWorkActivity(Just the next page)

AuthActivity()

class AuthActivity : AppCompatActivity(), AuthListener {
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    val API = API()
    val Pref = PreferenceProvider(this)
    val repository = UserRepository(API, Pref)
    val factory = AuthViewModelFactory(repository)

    // Getting data from UI

    val binding: ActivityAuthBinding = DataBindingUtil.setContentView(this, R.layout.activity_auth)
    val viewModel = ViewModelProviders.of(this, factory).get(AuthViewModel::class.java)
    binding.authViewModel = viewModel

    //

    viewModel.authListener = this
    viewModel.onActivated()


}

override fun onStarted() {
    toast("Аутентификация в процессе...")


}

override fun onSuccess(user: ValueAuth) {
    toast("Работник ${user.fio} вошел в систему")
}

override fun onFailure(message: String) {
    toast(message)
}

override fun navigateToSelectWork() {

    val nav = Intent(applicationContext, SelectWorkActivity::class.java)
    startActivity(nav)

}

override fun errorLogin(errorMessage: String) {
    login_input.error = errorMessage
    refocusError(login_input)
}

override fun errorPassword(errorMessage: String) {
    password_input.error = errorMessage
    refocusError(password_input)
}



private fun refocusError(componentToFocus: View) {
    if(componentToFocus.requestFocus()){
        window.setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE)
    }

}

override fun onActivate(info: SharePrefData) {
    super.onResume()
    val (login, password, checked) = info
    login_input.setText(login)
    password_input.setText(password)
    checkBox.isChecked = checked

}

}

AuthListener()

interface AuthListener {

fun onStarted()
fun onSuccess(user: ValueAuth)
fun onFailure(message: String)
fun navigateToSelectWork()
fun errorLogin(errorMessage: String)
fun errorPassword(errorMessage: String)
fun onActivate(info: SharePrefData)

}

AuthViewModel()

class AuthViewModel(
private val repository: UserRepository

): ViewModel() {

var email: String? = null
var password: String? = null
var authListener: AuthListener? = null
var onChecked: Boolean? = false







fun onActivated (){


    var onChecked: Boolean = repository.getBoolean()
    if(onChecked == true){


        authListener?.onActivate(repository.getInfo())

        authIn()
    } else {
        authListener?.onFailure("Введите ваши данные")
    }

}

fun onCheckedClick(view: View){
    onChecked = true
}

fun authIn(){

    authListener?.onStarted()

    Coroutines.main {


        try {
            val authResponse = repository.userAuth(email!!, password!!)



            authResponse.value?.let {
                repository.saveAuth(email!!, password!!, onChecked!!)
                authListener?.navigateToSelectWork()
                authListener?.onSuccess(it)


                return@main
            }
            authListener?.onFailure("Ошибка: ${authResponse.result!!.errMsg}")

        } catch (error: APIException){
            authListener?.onFailure(error.message!!)
        }
    }

}


fun onLoginButtonClicked(view: View) {

    if(email.isNullOrEmpty())
    {
        authListener?.errorLogin("Заполните ваш логин")
        false

    }
    else if(password.isNullOrEmpty())
    {
        authListener?.errorPassword("Заполните ваш пароль")
        false

    }
    else
    {
        authIn()
    }
    
}

}

UserRepository()

class  UserRepository(
private val API: API,
private val Preference: PreferenceProvider

): SaveAPIRequest() {

 suspend fun userAuth(email: String, password: String): AuthResponse {

         return APIRequest { API.userAuth(email, password) }

}

fun saveAuth(email: String, password: String, checked: Boolean){
    Preference.saveLastSavedAuth(email, password, checked)

}


fun getBoolean(): Boolean
{
    return Preference.getBoolean()
}

fun getInfo(): SharePrefData
{
    return Preference.getInfo()
}

}

PreferenceProvider()

private const val LOGIN_SAVED = "KEY_TO_LOGIN_SAVED"

private const val PASSWORD_SAVED = "KEY_TO_PASSWORD_SAVED" private const val CHECKED = "KEY_TO_CHECKED_SAVED"

class PreferenceProvider( context: Context ){ private var appContext = context.applicationContext private val preference: SharedPreferences get() = PreferenceManager.getDefaultSharedPreferences(appContext)

fun saveLastSavedAuth(savedLogin: String, savedPassword: String, savedChecked: Boolean){
    preference.edit().putString(LOGIN_SAVED, savedLogin).apply()
    preference.edit().putString(PASSWORD_SAVED, savedPassword).apply()
    preference.edit().putBoolean(CHECKED, savedChecked).apply()
}

fun getBoolean(): Boolean{
    return preference.getBoolean(CHECKED, false)
}

fun getInfo(): SharePrefData {

    val login = preference.getString(LOGIN_SAVED, "")
    val password = preference.getString(PASSWORD_SAVED, "")
    val checked = preference.getBoolean(CHECKED, false)

    return SharePrefData(login, password, checked)

}

fun doNotSaveLastSavedAuth(){

    preference.edit().putString(LOGIN_SAVED, "").apply()
    preference.edit().putString(PASSWORD_SAVED, "").apply()
    preference.edit().putBoolean(CHECKED, false).apply()
}

}