ViewBinding - 如何获得包含布局的绑定？

Question

在使用 ViewBinding 时，我遇到了一些没有记录的案例。

首先：如何获取包含的通用视图布局部分的绑定，主绑定只能看到主布局中的项目？

第二：如何获取包含的合并类型布局部分的绑定，再次主绑定只能看到主布局中的项目？

Answer 1

如果发生：

1. 包含通用布局（不是合并节点），我们需要为包含的部分分配 ID，这样在绑定中我们将可以访问包含的子部分

<include
    android:id="@+id/your_id"
    layout="@layout/some_layout" />

在你的活动代码中这样写：

private lateinit var exampleBinding: ActivityExampleBinding  //activity_example.xml layout

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    exampleBinding = ActivityExampleBinding.inflate(layoutInflater)
    setContentView(exampleBinding.root)
    //we will be able to access included layouts view like this
    val includedView: View = exampleBinding.yourId.idOfIncludedView
//[...]
}

1. 在外部布局中包含合并块。我们无法为其添加 ID，因为合并块不是视图。 假设我们有这样的永恒合并布局（merge_layout.xm）：

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:showIn="@layout/activity_example">

    <TextView
        android:id="@+id/some_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World" />
</merge>

要正确绑定这样的合并布局，我们需要：

在您的活动代码中：

private lateinit var exampleBinding: ActivityExampleBinding  //activity_example.xml layout
private lateinit var mergeBinding: MergeLayoutBinding  //merge_layout.xml layout

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    exampleBinding = ActivityExampleBinding.inflate(layoutInflater)
    //we need to bind the root layout with our binder for external layout
    mergeBinding = MergeLayoutBinding.bind(exampleBinding.root)
    setContentView(exampleBinding.root)
    //we will be able to access included in merge layout views like this
    val mergedView: View = mergeBinding.someView
//[...]
}

Answer 2

您的第一个问题，即使用 ViewBinding 处理包含的布局可以很容易地解决。

这是一个示例 ma​​in_fragment.xml 文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view_main"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar" />

</LinearLayout>

而MainFragment.java可以是这样的

public class MeaningFragment extends Fragment {

    private MainFragmentBinding binding;
    private ToolbarBinding toolbarBinding;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

        binding = MainFragmentBinding.inflate(inflater, container, false);
        toolbarBinding = binding.toolbar;

        return binding.getRoot();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();

        toolbarBinding = null;
        binding = null;
    }
}

现在，您有两个绑定。其中一个是默认的，下一个来自包含的布局。

Answer 3

如果你想绑定包含的布局，那么，

对于活动

YourMainLayoutBinding mainLayoutBinding = MainLayoutBinding.inflate(getLayoutInflater);

View view = mainLayoutBinding.getRoot();

YourIncludedLayoutBinding includedLayoutBinding = YourIncludedLayoutBinding.bind(View);

片段

YourMainLayoutBinding mainLayoutBinding = MainLayoutBinding.inflate(inflater,container,false);

View view = mainLayoutBinding.getRoot();

YourIncludedLayoutBinding includedLayoutBinding = YourIncludedLayoutBinding.bind(View);

确定如果你的主布局绑定父根是 LinearLayout 那么， includeLayoutBinding 父布局也是线性布局

Answer 4

假设我在activity_main.xml 文件中包含如下布局：

<include
    android:id="@+id/ll_layout1"
    layout="@layout/layout1"
    android:visibility="gone" />

假设我想改变它的可见性。我可以这样做：

activityMainBinding.llLayout1.root.visibility = View.VISIBLE

Answer 5

按照步骤：-

1. private val binding : FragmentBinding viewBinding(FragmentBinding::bind)

2. 确保在“onViewCreated(view: View, savedInstanceState: Bundle?)”中执行以下操作

    val binding2 = binding.root.include_layout_id
   

例如val binding2 = binding.root.tool_bar_layout

现在在此处访问您的包含布局和视图。例如

binding2.textView.text = "your text"

Answer 6

在包含布局中，您必须创建一个容器布局并将 id 放在这里。

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/example"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toTopOf="parent">
    </androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

Answer 7

使用数据绑定库。然后用 <layout> 标签包装你的 XML 布局

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<layout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    ... 

    <include 
      android:id="@+id/toolbar"
      layout="@layout/toolbar" />
    
    ...

</LinearLayout>
</layout>

toolbar.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView 
        android:id="@+id/ivImage"
        ... />

    <TextView 
        android:id="@+id/tvTitle"
        ... />


</LinearLayout>

MainActivity.kt

private lateinit var binding: ActivityMainBinding  

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = DataBindingUtil.setContentView(this, R.layout.activity_main)

    // Access include layout views
    binding.toolbar.rootView.ivImage.setImageResource(R.drawable.ic_back_arrow)
    binding.toolbar.rootView.tvTitle.text = getString(R.string.home)
   
    ...
}