viewmodel+livedata+binding 实现listview+adapter

首先listview 布局，这是一个fragment的layout,通过binding 自动注入！

fragment_yao_ce.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
    
    <data>
        <variable name="yaoCeAdapter" type="android.widget.BaseAdapter"/>
    </data>
    
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
  
        <ListView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/list_yaoce_view"
            app:adapter="@{yaoCeAdapter}"/> 

    </LinearLayout>
</layout>

对应 fragment 代码 kotlin：

var mContext : Context = context

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        var fragmentYaoCeBinding : FragmentYaoCeBinding = FragmentYaoCeBinding.inflate(inflater,
            container, false)
    
        //初始化 空list data
        var mListYaoCeData : List<YaoCe> = ArrayList<YaoCe>()
        //初始化 空的 属性展示 list
        var listViewProperty : MutableList<ItemThreeProperty> = ArrayList<ItemThreeProperty>()
        //添加title信息
        var itemThreeProperty = ItemThreeProperty()
        itemThreeProperty.indexNum = "序号"
        itemThreeProperty.strPropertyOne = "数值"
        itemThreeProperty.strPropertyTwo = "代号描述"
        itemThreeProperty.strPropertyThree = "信息"
        listViewProperty.add(itemThreeProperty)

        var adapter : ListAdapter<ItemThreeProperty> =  ListAdapter<ItemThreeProperty>(mContext, listViewProperty,
            R.layout.linear_text_three_item, BR.itemThree)
        val model = ViewModelProviders.of(this)[YaoCeViewModel::class.java]
        //做数据绑定和监听
        model.getYaoCe().observe(this, Observer<List<YaoCe>>{ yaoceList ->
            // update UI, data change
            if (yaoceList != null && yaoceList.isNotEmpty()){
                mListYaoCeData = yaoceList
                var listProperty = DataBeanToViewUtil.ListYaoCeBean2View(mListYaoCeData)
                for (property in listProperty) {
                    listViewProperty.add(property)
                }
                adapter.notifyDataSetChanged()
            }
        })
        //设置adapter 变量
        fragmentYaoCeBinding.setVariable(BR.yaoCeAdapter, adapter)
        //返回 view root
        return fragmentYaoCeBinding.root
    }

对应viewmodel+livedata

import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import com.daobo.wand.data.bean.SOE
import com.daobo.wand.data.bean.YaoCe
import kotlin.concurrent.thread

/**
 * 遥测
 * @author xiaolong.li
 * @time 2020-02-14
 */
class YaoCeViewModel : ViewModel() {
    var list : MutableList<YaoCe> = ArrayList<YaoCe>()
    //遥测信息
    private val listYaoCeData: MutableLiveData<List<YaoCe>> by lazy {
        MutableLiveData<List<YaoCe>>().also {
            loadData()
        }
    }

    /**
     *  获取数据
     */
    fun getYaoCe() : LiveData<List<YaoCe>> {
       return listYaoCeData
    }

    private fun loadData() {
        // Do an asynchronous operation to fetch data.
        //写死数据
        thread(start = true) {
            for(i in 1..30){
                val yaoCe = YaoCe()
                yaoCe.strMsg = "遥测 test"
                yaoCe.strValue = "10"
                yaoCe.numDesc = "点数"
                list.add(yaoCe)
            }
            listYaoCeData.postValue(list)
        }
    }

    fun refreshData() {
        thread(start = true) {
            val yaoCe = YaoCe()
            yaoCe.strMsg = "遥测 fresh add"
            yaoCe.strValue = "10"
            yaoCe.numDesc = "点数"
            list.add(yaoCe)
            listYaoCeData.postValue(list)
        }
    }
}

对应的 listview item 布局：统一使用的ItemTwoProperties bean,这就是为什么在fragment中，有一个bean 转换。

<?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">
    <data>
        <variable name="itemTwo" type="com.daobo.wand.data.viewbean.ItemTwoProperty"/>
    </data>
    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:id="@+id/num"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintHorizontal_weight="0.8"
            app:layout_constraintRight_toLeftOf="@+id/textOne"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:gravity="center_horizontal"
            android:background="@drawable/item_text_backgroud">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:text="@{itemTwo.indexNum}"
                android:textColor="@color/colorGray"
                android:textSize="16sp" />
        </LinearLayout>

        <LinearLayout
            android:id="@+id/textOne"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintHorizontal_weight="2"
            app:layout_constraintRight_toLeftOf="@+id/textTwo"
            app:layout_constraintLeft_toRightOf="@+id/num"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:gravity="center_horizontal"
            android:background="@drawable/item_text_backgroud">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:text="@{itemTwo.strPropertyOne}"
                android:textColor="@color/colorGray"
                android:textSize="16sp" />
        </LinearLayout>

        <LinearLayout
            android:id="@+id/textTwo"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintHorizontal_weight="4"
            app:layout_constraintLeft_toRightOf="@+id/textOne"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:gravity="center_horizontal">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:text="@{itemTwo.strPropertyTwo}"
                android:textColor="@color/colorGray"
                android:textSize="16sp" />
        </LinearLayout>

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

ListAdapter 代码：

import android.content.Context

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.BaseAdapter

import androidx.databinding.DataBindingUtil
import androidx.databinding.ViewDataBinding

// ListView 适配器 DataBindingUtil
/**
 * 统一的 list binding adapter
 * @author xiaolong.li
 * @time 2020-02-14
 */
class ListAdapter<T>(
    private val context: Context, private val list: List<T>,
    private val layoutId: Int, private val variableId: Int) : BaseAdapter() {

    override fun getCount(): Int {
        return list.size
    }

    override fun getItem(position: Int): Any {
        return list[position]!!
    }

    override fun getItemId(position: Int): Long {
        return position.toLong()
    }

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        var binding: ViewDataBinding? = null
        if (convertView == null) {
            binding = DataBindingUtil.inflate(LayoutInflater.from(context), layoutId, parent, false)
        } else {
            binding = DataBindingUtil.getBinding(convertView)
        }
        binding!!.setVariable(variableId, list[position])
        return binding.root
    }
}