databinding

官方地址：https://developer.android.google.cn/topic/libraries/data-binding
https://developer.android.google.cn/jetpack/androidx/releases/databinding?hl=zh_cn

B站地址：https://www.bilibili.com/video/BV1fY4y1i7BG?p=10&vd_source=c9e619eb6c2ba53337eccc49eb025732

android {
    ...
    buildFeatures {
        dataBinding true
    }
}

单向数据绑定

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        var dataBinding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
        dataBinding.user = User("张三")
        dataBinding.lifecycleOwner = this
    }
}

<?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="user"
            type="com.wy.databinding.User" />
    </data>

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

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{user.name}"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

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

data class User(var name:String)

数据双向绑定

class User(name:String){
     val _name =ObservableField<String>()
    init {
        _name.set(name)
    }
}

class MainActivity : AppCompatActivity() {
    private val user = User("张三")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val dataBinding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)
        dataBinding.user = user
        dataBinding.lifecycleOwner = this
        dataBinding.btnChangeName.setOnClickListener(View.OnClickListener {
            user._name.set("李四")
        })
    }
}

<?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="user"
            type="com.wy.databinding.User" />
    </data>

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

        <Button
            android:id="@+id/btnChangeName"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_constraintTop_toTopOf="parent"
            android:text="更改名字"/>

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{user._name}"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

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

自定义属性-BindingAdapter

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-kapt'
}

class Test {
    companion object{
        @BindingAdapter(value =["imageUrl"], requireAll = false)
        @JvmStatic
        fun test(imageView: ImageView, imageUrl:String) {
            Glide.with(imageView.context).load(imageUrl).into(imageView)
        }
    }
}

class BindingAdapterActivity : AppCompatActivity() {
    private val user = User("张三", "https://img0.baidu.com/it/u=2869855171,615441262&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_binding_adapter)
        val dataBinding = DataBindingUtil.setContentView<ActivityBindingAdapterBinding>(this, R.layout.activity_binding_adapter)
        dataBinding.user = user
        dataBinding.lifecycleOwner = this
    }
}

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

    <data>
        <variable
            name="user"
            type="com.wy.databinding.User" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".bindingadapter.BindingAdapterActivity">
        <ImageView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:imageUrl="@{user._imageUrl}"/>
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>