ItemBinding用法解析

引入ItemBinding

//Databinding
kapt "com.android.databinding:compiler:3.1.4"
// recyclerView的Databinding套装
implementation 'me.tatarka.bindingcollectionadapter2:bindingcollectionadapter:4.0.0'
implementation 'me.tatarka.bindingcollectionadapter2:bindingcollectionadapter-recyclerview:4.0.0'

viewModel+lifeCycle支持

//使用Providers创建viewmodel时用
implementation "android.arch.lifecycle:extensions:1.1.1"
implementation 'androidx.lifecycle:lifecycle-viewmodel:2.0.0'

Base_item_binding：绑定Item

<?xml version="1.0" encoding="utf-8"?>
<layout 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">

    <data>

        <variable
            name="item"
            type="com.example.diyview.Item" />

    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@color/greeen"
        android:padding="10dp">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@{item.title}"
            android:textColor="@color/white"
            android:textSize="18sp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            tools:ignore="MissingConstraints"
            tools:text="哈哈哈哈哈哈哈哈哈哈哈哈哈哈哈哈" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

Activity_main：绑定ViewModel

<?xml version="1.0" encoding="utf-8"?>
<layout 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">

    <data>

        <variable
            name="viewModel"
            type="com.example.diyview.main.MainViewModel" />

    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".main.MainActivity">

        <TextView
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="#03A9F4"
            android:gravity="center"
            android:text="我的自定义View系列"
            android:textColor="#ffffff"
            android:textSize="24sp"
            tools:ignore="MissingConstraints" />

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/mainRecycler"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            itemBinding="@{viewModel.itemBinding}"
            items="@{viewModel.items}"
            app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintTop_toBottomOf="@id/toolbar"
            tools:itemCount="3"
            tools:listitem="@layout/base_item_binding" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

ViewModel：数据

class MainViewModel : ViewModel() {

    val items = ObservableArrayList<Item>()
    val itemBinding = ItemBinding.of<Item>(BR.item, R.layout.base_item_binding)
            .bindExtra(BR.viewModel,this)
    init {
        items.add(Item("00自定义View系列：实心圆+文字"))
        items.add(Item("01自定义View系列：饼状图+数据"))
        items.add(Item("02自定义View系列：圆环"))
        items.add(Item("03自定义View系列：奥运五环"))
        items.add(Item("04自定义View系列：流式布局"))
        items.add(Item("05自定义View系列：加载Loading"))
        items.add(Item("0*自定义View系列：***"))
        items.add(Item("0*自定义View系列：***"))
        items.add(Item("0*自定义View系列：***"))
        items.add(Item("0*自定义View系列：***"))
        items.add(Item("0*自定义View系列：***"))
        items.add(Item("0*自定义View系列：***"))
        items.add(Item("0*自定义View系列：***"))
        items.add(Item("0*自定义View系列：***"))
    }
}

Activity数据与UI绑定

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityMainBinding dataBinding = DataBindingUtil.setContentView(this,R.layout.activity_main);
        MainViewModel viewModel = ViewModelProviders.of(this).get(MainViewModel.class);
        dataBinding.setViewModel(viewModel);
        dataBinding.setLifecycleOwner(this);
    }
}