1、简单使用

    dataBinding {
            enabled = true
        }

开启 databinding

新建bean

package com.anguomob.jecpack.bean

data class Idol(val name: String, val start: String)

针对布局做下面操作

首选选中根布局

然后选第一个

然后他会被这样的布局包围

用上我们刚才的变量

<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="idol"
            type="com.anguomob.jecpack.bean.Idol" />
    </data>

整个布局样式如下

但是android:text的属性是这样绑定的 @{idol.name}

或者

android:text="@{idol.start}"

<?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="idol"
            type="com.anguomob.jecpack.bean.Idol" />
    </data>

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

        <ImageView
            android:id="@+id/imageView"
            android:layout_width="250dp"
            android:layout_height="250dp"
            android:src="@mipmap/ic_launcher"
            app:layout_constraintBottom_toTopOf="@+id/guideline2"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_begin="309dp" />

        <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="68dp"
            android:text="@{idol.name}"
            android:textSize="24dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline2"
            tools:text="姓名" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="60dp"
            android:text="@{idol.start}"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView1"
            tools:text="年龄" />





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

页面布局也非常简单

package com.anguomob.jecpack.activity

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.databinding.DataBindingUtil
import com.anguomob.jecpack.R
import com.anguomob.jecpack.bean.Idol
import com.anguomob.jecpack.databinding.ActivityDatabindingBinding

class DatabindingActivity : AppCompatActivity() {
    lateinit var binding: ActivityDatabindingBinding
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_databinding)
        val idol = Idol("狗蛋", "5")
        binding.idol = idol;



    }
}

拿到数据设置上去即可。非常的简单。

2、使用import导入工具类转换

很多场景下是我们无法给到我们一星二星而是给我们1 2 3 4 5 Int类型数据

package com.anguomob.jecpack.bean

data class Idol(val name: String, val start: Int)

package com.anguomob.jecpack.utils

object StartUtils {
    fun getStar(star: Int): String {
        return when (star) {
            1 -> "一星"
            2 -> "二星"
            3 -> "三星"
            4 -> "四星"
            5 -> "五星"
            else -> ""
        }

    }
}

如何使用getStar方法呢

<?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="idol"
            type="com.anguomob.jecpack.bean.Idol" />

        <import type="com.anguomob.jecpack.utils.StartUtils" />
    </data>

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

        <ImageView
            android:id="@+id/imageView"
            android:layout_width="250dp"
            android:layout_height="250dp"
            android:src="@mipmap/ic_launcher"
            app:layout_constraintBottom_toTopOf="@+id/guideline2"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_begin="309dp" />

        <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="68dp"
            android:text="@{idol.name}"
            android:textSize="24dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline2"
            tools:text="姓名" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="60dp"
            android:text="@{StartUtils.INSTANCE.getStar(idol.start)}"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView1"
            tools:text="年龄" />


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

上图是导入

下面是使用

         android:text="@{StartUtils.INSTANCE.getStar(idol.start)}"

3 监听点击事件

首先写一个类去完成点击事件

package com.anguomob.jecpack.click

import android.content.Context
import android.view.View
import android.widget.Toast

class EventHandlerListener(var context: Context) {
    public fun buttonOnClick(view: View) {
        Toast.makeText(context, "喜欢", Toast.LENGTH_LONG).show()
    }
}

data里面新建variable

   <data>

        <variable
            name="idol"
            type="com.anguomob.jecpack.bean.Idol" />

        <variable
            name="eventHandler"
            type="com.anguomob.jecpack.click.EventHandlerListener" />

        <import type="com.anguomob.jecpack.utils.StartUtils" />
    </data>

新增一个按钮

        <Button
            android:id="@+id/button4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="52dp"
            android:onClick="@{eventHandler.buttonOnClick}"
            android:text="喜欢"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView2" />

并绑定单击事件

         android:onClick="@{eventHandler.buttonOnClick}"

完整layout代码

<?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="idol"
            type="com.anguomob.jecpack.bean.Idol" />

        <variable
            name="eventHandler"
            type="com.anguomob.jecpack.click.EventHandlerListener" />

        <import type="com.anguomob.jecpack.utils.StartUtils" />
    </data>

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

        <ImageView
            android:id="@+id/imageView"
            android:layout_width="250dp"
            android:layout_height="250dp"
            android:src="@mipmap/ic_launcher"
            app:layout_constraintBottom_toTopOf="@+id/guideline2"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_begin="309dp" />

        <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="68dp"
            android:text="@{idol.name}"
            android:textSize="24dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline2"
            tools:text="姓名" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="60dp"
            android:text="@{StartUtils.INSTANCE.getStar(idol.start)}"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView1"
            tools:text="年龄" />

        <Button
            android:id="@+id/button4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="52dp"
            android:onClick="@{eventHandler.buttonOnClick}"
            android:text="喜欢"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView2" />


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

页面当中也要加一句话

      binding.eventHandler = EventHandlerListener(this);

package com.anguomob.jecpack.activity

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.databinding.DataBindingUtil
import com.anguomob.jecpack.R
import com.anguomob.jecpack.bean.Idol
import com.anguomob.jecpack.click.EventHandlerListener
import com.anguomob.jecpack.databinding.ActivityDatabindingBinding

class DatabindingActivity : AppCompatActivity() {
    lateinit var binding: ActivityDatabindingBinding
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_databinding)
        val idol = Idol("狗蛋", 5)
        binding.idol = idol;
        binding.eventHandler = EventHandlerListener(this);


    }
}

这样点击就可以生效了

点击事件就被解耦到别的地方了

4 将data数据传到inclue下面的二级页面

有时候我们会复用某些布局。让页面显得更加的简单与及时更新

<?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="idol"
            type="com.anguomob.jecpack.bean.Idol" />

        <variable
            name="eventHandler"
            type="com.anguomob.jecpack.click.EventHandlerListener" />

    </data>

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

        <ImageView
            android:id="@+id/imageView"
            android:layout_width="250dp"
            android:layout_height="250dp"
            android:src="@mipmap/ic_launcher"
            app:layout_constraintBottom_toTopOf="@+id/guideline2"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_begin="309dp" />

        <include
            layout="@layout/sub"
            android:layout_width="0dp"
            android:layout_height="0dp"
            app:idol="@{idol}"
            app:eventHandler="@{eventHandler}"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/guideline2" />


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

sub 页面

<?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="idol"
            type="com.anguomob.jecpack.bean.Idol" />

        <variable
            name="eventHandler"
            type="com.anguomob.jecpack.click.EventHandlerListener" />

        <import type="com.anguomob.jecpack.utils.StartUtils" />
    </data>

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


        <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{idol.name}"
            android:textSize="24dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            tools:text="姓名" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="60dp"
            android:text="@{StartUtils.INSTANCE.getStar(idol.start)}"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView1"
            tools:text="年龄" />

        <Button
            android:id="@+id/button4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="52dp"
            android:onClick="@{eventHandler.buttonOnClick}"
            android:text="喜欢"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView2" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

如何将一级页面的数据传递到sub下面呢

            app:idol="@{idol}"
            app:eventHandler="@{eventHandler}"

使用这种方法进行传递

Android jetpack dataBinding layout与activity解耦

1、简单使用

2、使用import导入工具类转换

3 监听点击事件

4 将data数据传到inclue下面的二级页面

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