带有协同程序的Android MVVM Jetpack导航组件

我正在尝试实现android jetpack导航组件。 该案例与官方文件中的情况几乎相同：

但我的情况是，如果用户尚未登录，登录访问将记录在数据库（房间）中， 然后系统将强制用户登录。 我过去经常申报 登录片段的目标

然后依次定义如下

家庭碎片是开始的目标

如果在数据库中未找到用户数据，则显示登录页面

如果登录成功，请将用户带回主页并将登录数据保存到数据库

我使用MVVM体系结构和协同程序来运行REST请求 使用改装

以下是我使用的一些代码：

导航（xml）

家庭碎片

 class HomeFragment : Fragment() {

     ?? Should I usede LoginViewModel ?

     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
         return inflater.inflate(R.layout.fragment_home, container, false)
     }

     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
         observeAuthenticationState()
     }

     private fun observeAuthenticationState() {
         val navController = findNavController()

         // REDIRECT USER TO LOGIN PAGE ?
         // How To check it
         navController.navigate(R.id.action_global_loginFragment)
     }   
 }

登录片段

 class LoginFragment : Fragment() {

     private lateinit var viewModel: LoginViewModel // How can I shared this to home fragment
     private lateinit var binding: FragmentLoginBinding

     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {

         // For Retrofit
         val networkConnectionInterceptor = NetworkConnectionInterceptor(requireContext())
         val api = MyApi(networkConnectionInterceptor)

         // For Room
         val db = AppDatabase(context = requireActivity().applicationContext)

         // For ViewModel
         val repository = UserRepository(api, db)
         val factory = LoginViewModelFactory(repository)

         binding = DataBindingUtil.inflate(
             inflater,
             R.layout.fragment_login,
             container,
             false
         )

         viewModel = ViewModelProvider(this, factory).get(LoginViewModel::class.java)
         binding.buttonLogin.setOnClickListener { loginUser() }
         return binding.root
     }

     private fun loginUser() {
         val username = binding.editTextUsername.text.toString().trim()
         val password = binding.editTextPassword.text.toString().trim()

         binding.progressBar.show()
         lifecycleScope.launch {
             try {
                 val loginResponse = viewModel.userLogin(username!!, password!!)

                 if(loginResponse.user != null){
                     viewModel.saveLoggedInUser(loginResponse.user)
                 }

                 binding.progressBar.hide()
                 binding.root.context.toast(loginResponse.message!!)

             } catch (e: ApiException) {
                 binding.progressBar.hide()
                 binding.root.context.toast( e.toString())
             } catch (e: NoInternetException) {
                 binding.progressBar.hide()
                 binding.root.context.toast( e.toString())
             }
         }
     }
 }

我的问题

如何强制用户在主片段上正确登录片段

如何在HomeFragment上使用LoginViewModel

 class HomeFragment : Fragment() {

     ?? Should I usede LoginViewModel ?

     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
         return inflater.inflate(R.layout.fragment_home, container, false)
     }

     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
         observeAuthenticationState()
     }

     private fun observeAuthenticationState() {
         val navController = findNavController()

         // REDIRECT USER TO LOGIN PAGE ?
         // How To check it
         navController.navigate(R.id.action_global_loginFragment)
     }   
 }

 class LoginFragment : Fragment() {

     private lateinit var viewModel: LoginViewModel // How can I shared this to home fragment
     private lateinit var binding: FragmentLoginBinding

     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {

         // For Retrofit
         val networkConnectionInterceptor = NetworkConnectionInterceptor(requireContext())
         val api = MyApi(networkConnectionInterceptor)

         // For Room
         val db = AppDatabase(context = requireActivity().applicationContext)

         // For ViewModel
         val repository = UserRepository(api, db)
         val factory = LoginViewModelFactory(repository)

         binding = DataBindingUtil.inflate(
             inflater,
             R.layout.fragment_login,
             container,
             false
         )

         viewModel = ViewModelProvider(this, factory).get(LoginViewModel::class.java)
         binding.buttonLogin.setOnClickListener { loginUser() }
         return binding.root
     }

     private fun loginUser() {
         val username = binding.editTextUsername.text.toString().trim()
         val password = binding.editTextPassword.text.toString().trim()

         binding.progressBar.show()
         lifecycleScope.launch {
             try {
                 val loginResponse = viewModel.userLogin(username!!, password!!)

                 if(loginResponse.user != null){
                     viewModel.saveLoggedInUser(loginResponse.user)
                 }

                 binding.progressBar.hide()
                 binding.root.context.toast(loginResponse.message!!)

             } catch (e: ApiException) {
                 binding.progressBar.hide()
                 binding.root.context.toast( e.toString())
             } catch (e: NoInternetException) {
                 binding.progressBar.hide()
                 binding.root.context.toast( e.toString())
             }
         }
     }
 }