带有视图绑定的 BaseFragment

Question

为了在 Android 应用程序中使用，我基本上是为&viewbinding创建基类，以删除每次编写膨胀代码的样板。ActivityFragment

活动：

BaseActivity和viewbinding：

abstract class BaseActivity<VB : ViewBinding> : AppCompatActivity() {
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = getViewBinding()
    }

    abstract fun getViewBinding(): VB

}

MainActivity:

class MainActivity : BaseActivity<ActivityMainBinding>() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)
        //we can directly use binding now and it works fine inside activity
        //binding.view.doSomething() 
    }

 override fun getViewBinding(): ActivityMainBinding = ActivityMainBinding.inflate(layoutInflater)
}

片段：

BaseFragment:

abstract class BaseFragment<VB : ViewBinding> : Fragment() {

    var binding: VB? = null

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

    abstract fun getViewBinding(view: View): VB
}

DemoFragment:

class DemoFragment : BaseFragment<DemoFragmentBinding>() {

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        //problem is here
        binding.txtData.text="Something"
    }

    override fun getViewBinding(view: View): DemoFragmentBinding = DemoFragmentBinding.bind(view)

}

demo_fragment.xml：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.fragments.DemoFragment">

    <TextView
        android:id="@+id/txt_data"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="Hello" />

</FrameLayout>

问题：无法使用 Demofragment 内的绑定访问视图。我不知道为什么它适用于 Activity 而不适用于 Fragment。

我不想做的第二种方式：

实现 'androidx.fragment:fragment-ktx:1.3.1'

class DemoFragment : Fragment(R.layout.demo_fragment) {

    lateinit var binding: DemoFragmentBinding

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        binding = DemoFragmentBinding.bind(view).apply {
            txtData.text = "Hello World"
        }
    }
}

Answer 1

您需要onCreateView在 BaseFragment 中重写并初始化视图绑定

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    _binding = getViewBinding()
    return binding.root
}

然后改变这一行

override fun getViewBinding(view: View): DemoFragmentBinding = DemoFragmentBinding.bind(view)

和

override fun getViewBinding() = DemoFragmentBinding.inflate(layoutInflater)

基础片段：

abstract class BaseFragment<VB : ViewBinding> : Fragment() {
    private var _binding: VB? = null
    val binding get() = _binding!!

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        _binding = getViewBinding()
        return binding.root
    }

    abstract fun getViewBinding(): VB
}

演示片段：

class DemoFragment : BaseFragment<DemoFragmentBinding>() {

    override fun getViewBinding() = DemoFragmentBinding.inflate(layoutInflater)

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

        binding.apply {
            txtData.text = "Something"
        }
    }
}