最近Android Studio 升级后 butterknife 有一个警告:
Resource IDs will be non-final in Android Gradle Plugin version 5.0, avoid using them as annotation attributes
查看官网发现：
butterknife已经弃用，建议使用 view binding 替换。
官方介绍：
通过视图绑定功能，您可以更轻松地编写可与视图交互的代码。在模块中启用视图绑定之后，系统会为该模块中的每个 XML 布局文件生成一个绑定类。绑定类的实例包含对在相应布局中具有 ID 的所有视图的直接引用。
在大多数情况下，视图绑定会替代 findViewById。
android {
...
viewBinding {
enabled = true
}
buildFeatures {
viewBinding = true
}
}
在 Activity 的 onCreate() 方法中执行以下步骤：
private ResultProfileBinding binding;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
binding = ResultProfileBinding.inflate(getLayoutInflater());
View view = binding.getRoot();
setContentView(view);
}
现在即可使用该绑定类的实例来引用任何视图：
binding.getName().setText(viewModel.getName());
binding.button.setOnClickListener(new View.OnClickListener() {
viewModel.userClicked()
});
现在即可使用该绑定类的实例来引用任何视图：
binding.getName().setText(viewModel.getName());
binding.button.setOnClickListener(new View.OnClickListener() {
viewModel.userClicked()
});
在 Fragment 的 onCreateView() 方法中执行以下步骤：
private ResultProfileBinding binding;
@Override
public View onCreateView (LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
binding = ResultProfileBinding.inflate(inflater, container, false);
View view = binding.getRoot();
return view;
}
@Override
public void onDestroyView() {
super.onDestroyView();
binding = null;
}
public class TestAdapter extends BaseAdapter {
private List datas;
private final LayoutInflater mInflater;
public TestAdapter(List datas, Context context) {
this.datas = datas;
this.mInflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
return datas.size();
}
@Override
public Object getItem(int i) {
return i;
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
ViewHolder viewHolder;
if (view == null) {
AdapterTestBinding binding = AdapterTestBinding.inflate(mInflater, viewGroup, false);
viewHolder = new ViewHolder(binding);
view = binding.getRoot();
view.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) view.getTag();
}
viewHolder.binding.tvContent.setText(datas.get(i));
return view;
}
static class ViewHolder {
private final AdapterTestBinding binding;
public ViewHolder(AdapterTestBinding binding) {
this.binding = binding;
}
}
}
项目运行后，每个布局文件都会生成对应的binding类，比如 activity_main.xml 会生成 ActivityMainBinding.java 文件，路径如下：
app\build\generated\data_binding_base_class_source_out\debug\out\包名\databinding
代码其实很简单就是加载布局，然后对控件进行初始化：
public final class ActivityMainBinding implements ViewBinding {
@NonNull
private final LinearLayout rootView;
@NonNull
public final WebView wv;
private ActivityMainBinding(@NonNull LinearLayout rootView, @NonNull WebView wv) {
this.rootView = rootView;
this.wv = wv;
}
@Override
@NonNull
public LinearLayout getRoot() {
return rootView;
}
@NonNull
public static ActivityMainBinding inflate(@NonNull LayoutInflater inflater) {
return inflate(inflater, null, false);
}
@NonNull
public static ActivityMainBinding inflate(@NonNull LayoutInflater inflater,
@Nullable ViewGroup parent, boolean attachToParent) {
View root = inflater.inflate(R.layout.activity_main, parent, false);
if (attachToParent) {
parent.addView(root);
}
return bind(root);
}
@NonNull
public static ActivityMainBinding bind(@NonNull View rootView) {
// The body of this method is generated in a way you would not otherwise write.
// This is done to optimize the compiled bytecode for size and performance.
String missingId;
missingId: {
WebView wv = rootView.findViewById(R.id.wv);
if (wv == null) {
missingId = "wv";
break missingId;
}
return new ActivityMainBinding((LinearLayout) rootView, wv);
}
throw new NullPointerException("Missing required view with ID: ".concat(missingId));
}
}
ViewBinding 的源码如下：
public interface ViewBinding {
/**
* Returns the outermost {@link View} in the associated layout file. If this binding is for a
* {@code } layout, this will return the first view inside of the merge tag.
*/
@NonNull
View getRoot();
}
可以对代码稍加改造，减少 Activity 、Fragment 、Adapter 中的重复代码。
public abstract class BaseActivityextends AppCompatActivity { protected T binding; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); binding = getBinding(); setContentView(binding.getRoot()); } protected abstract T getBinding(); }
public abstract class BaseFragmentextends Fragment { protected Context context; protected T binding; @Nullable @Override public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { binding = getBinding(inflater, container); return binding.getRoot(); } protected abstract T getBinding(LayoutInflater inflater, ViewGroup container); @Override public void onDestroyView() { super.onDestroyView(); binding = null; } @Override public void onAttach(@NonNull Context context) { super.onAttach(context); this.cOntext= context; } @Override public void onDetach() { super.onDetach(); this.cOntext= null; } }
public class TestFragment extends BaseFragment{ @Override public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); binding.tvContent.setText("this is test"); } @Override protected FragmentTestBinding getBinding(LayoutInflater inflater, ViewGroup container) { return FragmentTestBinding.inflate(inflater, container, false); } }
public abstract class MyAdapterextends BaseAdapter { private final LayoutInflater inflater; public MyAdapter(Context context) { inflater = LayoutInflater.from(context); } @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder holder; if (null == convertView) { T binding = getBinding(inflater, parent); holder = new ViewHolder(binding); cOnvertView= binding.getRoot(); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } handleData(position, holder.binding); return convertView; } protected abstract void handleData(int position, T binding); protected abstract T getBinding(LayoutInflater inflater, ViewGroup parent); class ViewHolder { private final T binding; public ViewHolder(T binding) { this.binding = binding; } } }
public class TestAdapter extends MyAdapter{ private List datas; public TestAdapter(List datas, Context context) { super(context); this.datas = datas; } @Override public int getCount() { return datas.size(); } @Override public Object getItem(int i) { return i; } @Override public long getItemId(int i) { return i; } @Override protected void handleData(int position, AdapterTestBinding binding) { binding.tvContent.setText(datas.get(position)); } @Override protected AdapterTestBinding getBinding(LayoutInflater inflater, ViewGroup parent) { return AdapterTestBinding.inflate(inflater, parent, false); } }
如果布局中有使用
<&＃63;xml version="1.0" encoding="utf-8"&＃63;>
<&＃63;xml version="1.0" encoding="utf-8"&＃63;>
public class TestFragment extends BaseFragment{ @Override public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); binding.tvContent.setText("this is test"); //通过 include 的id找到对应的控件 binding.viewTitle.tvTitle.setText("this is title"); } @Override protected FragmentTestBinding getBinding(LayoutInflater inflater, ViewGroup container) { return FragmentTestBinding.inflate(inflater, container, false); } }
以上就是Android ViewBinding的使用详解的详细内容，更多关于Android ViewBinding的使用的资料请关注其它相关文章！
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