DataBindingAdapter for RecyclerView

MultiTypeBindingAdapter.kt

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.databinding.DataBindingUtil
import androidx.databinding.ViewDataBinding
import androidx.recyclerview.widget.RecyclerView
import kotlin.reflect.KClass

/**
 * # MultiTypeBindingAdapter
 *
 * Created on 2020/6/16
 * @author Vove
 */
fun multiTypeBindingAdapter(
    dataSet: List<Any>,
    dbIdLayoutGetter: (item: Any) -> Pair<Int, Int>
): MultiTypeBindingAdapter {
    return MultiTypeBindingAdapter(dataSet, dbIdLayoutGetter)
}

fun <T : Any> bindingAdapter(
    dataSet: List<T>,
    dbId: Int,
    layId: Int
): BindingAdapter<T> = BindingAdapter(dataSet, dbId, layId)

open class MultiTypeBindingAdapter(
    private val dataSet: List<Any>,
    val dbIdLayoutGetter: (typeCls: KClass<*>) -> Pair<Int, Int>
) : RecyclerView.Adapter<BindingViewHolder>() {

    private val typeMap = mutableMapOf<Int, KClass<*>>()

    private fun getItem(p: Int): Any = dataSet[p]

    override fun getItemViewType(position: Int): Int {
        val type = (getItem(position) as Object).`class`.name.hashCode()
        typeMap[type] = getItem(position)::class
        return type
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BindingViewHolder {
        val (dbId, lId) = dbIdLayoutGetter(typeMap[viewType]!!)
        val binding = DataBindingUtil.inflate<ViewDataBinding>(
            LayoutInflater.from(parent.context),
            lId,
            parent,
            false
        )
        return BindingViewHolder(binding.root.also {
            it.setTag(R.id.tag_adapter_databinding_support, binding)
        }, dbId)
    }

    override fun getItemCount(): Int = dataSet.size

    override fun onBindViewHolder(holder: BindingViewHolder, position: Int) {
        holder.binding.apply {
            setVariable(holder.dbId, dataSet[position])
            executePendingBindings()
        }
    }

}

open class BindingAdapter<T : Any>(
    dataSet: List<T>,
    private val dbId: Int,
    private val layId: Int
) : MultiTypeBindingAdapter(dataSet, { dbId to layId })


class BindingViewHolder(itemView: View, val dbId: Int) : RecyclerView.ViewHolder(itemView) {
    val binding: ViewDataBinding
        get() = itemView.getTag(R.id.tag_adapter_databinding_support) as ViewDataBinding
}

单一类型数据

数据类：

data class ListItem(
    val id: Int,
    val name: String
)

列表布局(item_demo_list.xml)：

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable
            name="item"
            type="xxx.model.ListItem" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_vertical">
        <TextView
            android:layout_width="50dp"
            android:layout_height="50dp"
            android:gravity="center"
            android:text="@{String.valueOf(item.id)}"
            android:textSize="20sp"
            android:textStyle="bold" />
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{item.name}" />
    </LinearLayout>
</layout>

创建 Adapter :

recyclerView.adapter = bindingAdapter(multiList, BR.item, R.layout.item_demo_list)

多种布局类型：

添加一个数据类：

data class ListItem2(val icon: String)

布局 item_demo_list2.xml 省略...

创建Adapter：

recyclerView.adapter = multiTypeBindingAdapter(multiList) { kcls ->
    when (kcls) {
        ListItem::class -> BR.item to R.layout.item_demo_list
        ListItem2::class -> BR.item2 to R.layout.item_demo_list2
        else -> throw Exception("unsupport type $kcls")
    }
}

也可以继承其他已封装的Adapter