​ View Binding是一种功能，允许开发者更容易的编写与视图交互的代码。

​ 一旦在一个模块中启用了View Binding，它就会为该模块中存在的每个XML布局文件生成一个绑定类

如何启用View Binding

​ 在build.gradle的android{}中添加代码

buildFeatures{
        viewBinding true
    		 }

如何使用View Binding

在Activity中使用View Binding

private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    binding = ActivityMainBinding.inflate(layoutInflater)
    setContentView(binding.root)
}
ActivityMainBinding mainBinding;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mainBinding = ActivityMainBinding.inflate(getLayoutInflater());
    setContentView(mainBinding.getRoot());
}

然后就可以使用binding对象来访问视图

binding.textview.text = "hello world"
mainBinding.textview.setText("hello world");

在Fragment中使用View Binding

private lateinit var binding: FragmentBlankBinding

override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    binding = FragmentBlankBinding.inflate(layoutInflater)
    return binding.root
}
private FragmentMainBinding fmBinding;
    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        fmBinding = FragmentMainBinding.inflate(inflater,container,false);
        //在这里写界面逻辑等
        return fmBinding.getRoot();
    }
	//在onDestroyView()中清理Binding对象防止内存泄漏
    @Override
    public void onDestroyView() {
        super.onDestroyView();
        fmBinding = null;
    }

然后就可以像在Activity中一样去使用它了

在RecycleViewAdapter中使用View Binding

//使用binding class作为root layout
class ViewHolder(var viewBinding: MainlistItemBinding):RecyclerView.ViewHolder(viewBinding.root) {
}
//inflate内容并返回viewholder
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
    val binding = MainlistItemBinding.inflate(LayoutInflater.
                                              from(parent.context),parent,false)
    return ViewHolder(binding)
}
//在onBindViewHolde中直接使用
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    val mainlistItemBinding = holder as MainlistItemBinding
    val fruit = fruitList[position]
    mainlistItemBinding.fruitname.text = fruit.name
}
public class MainAdapter extends RecyclerView.Adapter<MainAdapter.MainViewHolder> {
    @NonNull
    @NotNull
    @Override
    public MainViewHolder onCreateViewHolder(@NonNull @NotNull ViewGroup parent, int viewType) {
        return new MainViewHolder(MainrecyItemBinding.
                                  inflate(LayoutInflater.from(parent.getContext())
                                          ,parent,false));
    }

    @Override
    public void onBindViewHolder(@NonNull @NotNull MainViewHolder holder, int position) {
        
    }

    @Override
    public int getItemCount() {
        return 0;
    }

    public class MainViewHolder extends RecyclerView.ViewHolder {
        //MainrecyItemBinding为该recyclerview的子控件
        MainrecyItemBinding mrBinding;
        public MainViewHolder(MainrecyItemBinding itemBinding) {
            super(itemBinding.getRoot());
            this.mrBinding = itemBinding;
        }
    }
}

在使用<include>时使用viewBinding

include标签下必须添加id

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

java代码中表示为：

ActivityMainBinding.titlebar.xxxbtn

来获取<include>中的控件