使用 Fragment Factory 和 Navigation Component 时，View 没有设置 NavController

Question

我正在重构我的应用程序以使用 Fragment Factory。在重构之前，导航组件一切正常，但现在片段无法再找到导航控制器，错误：

java.lang.IllegalStateException: View androidx.constraintlayout.widget.ConstraintLayout{7c24bdc V.E...... ......I. 0,0-1080,2088 #7f0a0061 app:id/auth_nav_host_fragment} does not have a NavController set
    at androidx.navigation.Navigation.findNavController(Navigation.java:84)
    at androidx.navigation.fragment.NavHostFragment.findNavController(NavHostFragment.java:118)
    at androidx.navigation.fragment.FragmentKt.findNavController(Fragment.kt:29)
    at com.kalianey.oneness.ui.auth.LauncherFragment.navLogin(LauncherFragment.kt:42)
    at com.kalianey.oneness.ui.auth.LauncherFragment.access$navLogin(LauncherFragment.kt:16)
    at com.kalianey.oneness.ui.auth.LauncherFragment$onViewCreated.onClick(LauncherFragment.kt:28)

我创建了一个片段工厂：

@AuthScope
class AuthFragmentFactory
@Inject
constructor(
private val viewModelFactory: ViewModelProvider.Factory
) : FragmentFactory() {

override fun instantiate(classLoader: ClassLoader, className: String) =

    when (className) {

        OnboardingPagerFragment::class.java.name -> {
            OnboardingPagerFragment()
        }

        OnboardingOneFragment::class.java.name -> {
            OnboardingOneFragment()
        }

        OnboardingTwoFragment::class.java.name -> {
            OnboardingTwoFragment()
        }

        OnboardingThreeFragment::class.java.name -> {
            OnboardingThreeFragment()
        }

        LauncherFragment::class.java.name -> {
            LauncherFragment(viewModelFactory)
        }

        LoginFragment::class.java.name -> {
            LoginFragment(viewModelFactory)
        }

        RegisterFragment::class.java.name -> {
            RegisterFragment(viewModelFactory)
        }

        ForgotPasswordFragment::class.java.name -> {
            ForgotPasswordFragment(viewModelFactory)
        }

        else -> {
            LauncherFragment(viewModelFactory)
        }
    }

 }

在我的模块中是这样提供的：

@JvmStatic
@AuthScope
@Provides
fun provideFragmentFactory(viewModelFactory: ViewModelProvider.Factory, requestManager: RequestManager, sessionManager: SessionManager): FragmentFactory{
    return AuthFragmentFactory(viewModelFactory)
}

我在 AuthActivity 中这样设置：

override fun onCreate(savedInstanceState: Bundle?) {
    inject()
    supportFragmentManager.fragmentFactory = fragmentFactory
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_auth)
}

我做错了什么？

Answer 1

当您设置 FragmentFactory 时，它负责实例化每个片段 AuthActivity 可能需要的。但是，当系统尝试实例化 NavHostFragment 时，您的工厂会创建一个 LauncherFragment。这意味着您实际上从未创建过 NavHostFragment，并且您没有 NavController.

您的 else 案例不应创建 LauncherFragment，而是应创建所请求的片段 class。

else -> {
    super.instantiate(classLoader, className)
}

使用 Fragment Factory 和 Navigation Component 时，View 没有设置 NavController

View does not have a NavController set when using Fragment Factory and Navigation Component

android

dagger-2

android-jetpack

android-architecture-navigation