• Android 使用Kotlin封装RecyclerView

    文章目录

    1.概述

    在一个开源项目上看到了一个Android Kotlin版的RecyclerView封装，个人觉得非常方便，所以就将这个封装摘了出来，记录下，方便以后使用，这个开源的项目叫DanDanPlayForAndroid点击链接可以查看具体的开源项目代码。

    2.运行效果图

    在这里插入图片描述在这里插入图片描述
    在这里插入图片描述在这里插入图片描述

    3.代码实现

    3.1 扩展RecyclerView

    我们可以通过Kotlin的扩展函数扩展RecycleView的布局方式，设置数据等功能，方便我们调用。代码如下：

    fun RecyclerView.vertical(
    reverse: Boolean = false
): LinearLayoutManager {
    return LinearLayoutManager(
        context,
        LinearLayoutManager.VERTICAL,
        reverse
    )
}

fun RecyclerView.horizontal(
    reverse: Boolean = false
): LinearLayoutManager {
    return LinearLayoutManager(
        context,
        LinearLayoutManager.HORIZONTAL,
        reverse
    )
}

fun RecyclerView.grid(
    spanCount: Int
): GridLayoutManager {
    return GridLayoutManager(context, spanCount)
}

fun RecyclerView.gridEmpty(spanCount: Int): GridLayoutManager {
    return GridLayoutManager(context, spanCount).also {
        it.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup() {
            override fun getSpanSize(position: Int): Int {
                if (position == RecyclerView.NO_POSITION) {
                    return 1
                }

                val viewType = adapter?.getItemViewType(position)
                if (viewType != -1) {
                    return 1
                }

                return spanCount
            }
        }
    }
}

fun RecyclerView.setData(itemData: List<Any>) {
    (adapter as RVBaseAdapter).setData(itemData)
}

fun RecyclerView.requestIndexChildFocus(index: Int): Boolean {
    scrollToPosition(index)
    val targetTag = "tag_focusable_item"
    val indexView = layoutManager?.findViewByPosition(index)
    if (indexView != null) {
        indexView.findViewWithTag<View>(targetTag)?.requestFocus()
        return true
    }

    post {
        layoutManager?.findViewByPosition(index)
            ?.findViewWithTag<View>(targetTag)
            ?.requestFocus()
    }

    return true
}

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    3.2 扩展Adapter

    在扩展Adapter之前，我们需要先定义一个我们自己的Adapter,然后再基于我们自己的Adapter去做扩展，代码如下：

    class RVBaseAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
    companion object{
        // the data of empty layout
        val EMPTY_ITEM = Any()

        // view type of empty layout
        const val VIEW_TYPE_EMPTY = -1

        // number of max item
        private const val NUMBER_OF_MAX_VIEW_TYPE = Int.MAX_VALUE -1
    }

    val itemData: MutableList<Any> = mutableListOf()

    private val typeHolders = 
    SparseArrayCompat<BaseViewHolderCreator<out ViewDataBinding>>()
    override fun onCreateViewHolder(
        parent: ViewGroup,
        viewType: Int
    ): RecyclerView.ViewHolder {
        return BaseViewHolder(
            DataBindingUtil.inflate(
                LayoutInflater.from(parent.context),
                getHolderCreator(viewType).getResourceId(),
                parent,
                false
            )
        )
    }

    private fun getHolderCreator(viewType: Int): 
    BaseViewHolderCreator<out ViewDataBinding> {
        return typeHolders.get(viewType)
            ?: throw java.lang.RuntimeException()
    }

    override fun getItemCount(): Int {
        return itemData.size
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder,
     position: Int) {
        getHolderCreator(holder.itemViewType).apply {
            initItemBinding(holder.itemView)
            onBindViewHolder(itemData[position],position,this)
        }
    }

    fun setData(dataList: List<Any>) {
        itemData.clear()
        itemData.addAll(dataList)

        // show the empty layout when data is empty
        if(itemData.isEmpty() && typeHolders.containsKey(VIEW_TYPE_EMPTY)){
            itemData.add(EMPTY_ITEM)
        }

        notifyDataSetChanged()
    }

    fun register(creator: BaseViewHolderCreator<out ViewDataBinding>, 
    customViewType: Int? = null) {
        apply {
            var viewType = customViewType ?: typeHolders.size()
            while (typeHolders.get(viewType) != null) {
                viewType++
                require(viewType < NUMBER_OF_MAX_VIEW_TYPE) {
                    "the number of view type has reached the maximum limit"
                }
            }

            require(viewType < NUMBER_OF_MAX_VIEW_TYPE) {
                "the number of view type has reached the maximum limit"
            }

            typeHolders.put(viewType, creator)
        }
    }

    override fun getItemViewType(position: Int): Int {
        if(itemData[position] == EMPTY_ITEM
            && typeHolders.containsKey(VIEW_TYPE_EMPTY)){
            return VIEW_TYPE_EMPTY
        }

        // only one viewHolder
        if(typeHolders.size() == 1){
            return typeHolders.keyAt(0)
        }

        // more than one viewHolder
        for (i in 0 until typeHolders.size()){
            if(typeHolders.keyAt(i) == VIEW_TYPE_EMPTY){
                continue
            }

            val holder = typeHolders.valueAt(i)
            if(holder.isForViewType(itemData[position],position)){
                return typeHolders.keyAt(i)
            }
        }

        throw java.lang.IllegalStateException(
            "no holder added that matches at position: $position in data source"
        )
    }
}

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    与上面代码相关联的抽象类：

    class BaseViewHolder(binding: ViewDataBinding) :
 RecyclerView.ViewHolder(binding.root) {
}

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    abstract class BaseViewHolderCreator<V : ViewDataBinding> {
    abstract fun isForViewType(data: Any?, position: Int): Boolean
    abstract fun getResourceId(): Int
    abstract fun onBindViewHolder(
        data: Any?,
        position: Int,
        creator: BaseViewHolderCreator<out ViewDataBinding>
    )

    lateinit var itemDataBinding: V

    fun initItemBinding(itemView: View) {
        this.itemDataBinding = DataBindingUtil.getBinding(itemView)!!
    }
}

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    抽象类的实现：

    class BaseViewHolderDSL<T : Any, V : ViewDataBinding>(
    private val resourceId: Int,
    private val clazz: KClass<T>
) : BaseViewHolderCreator<V>() {
    private var checkViewType: ((data: Any, position: Int) -> Boolean)? = null

    private var viewHolder: (
        (data: T, position: Int, creator:
         BaseViewHolderCreator<out ViewDataBinding>) -> Unit
    )? = null

    private var emptyViewHolder: (() -> Unit)? = null
    override fun isForViewType(data: Any?, position: Int): Boolean {
        if(data == null){
            return false
        }

        if(checkViewType != null){
            return checkViewType!!.invoke(data,position)
        }

        return clazz.isInstance(data)
    }

    /**
     * judge the type of current item data according to position
     */

    fun checkType(viewType:(data:Any,position:Int) ->Boolean){
        this.checkViewType = viewType
    }

    fun initView(
        holder:(
            data:T,
            position:Int,
            holder:BaseViewHolderCreator<out ViewDataBinding>
        )->Unit
    ){
        this.viewHolder = holder
    }

    override fun getResourceId(): Int {
        return resourceId
    }

    override fun onBindViewHolder(
        data: Any?,
        position: Int,
        creator: BaseViewHolderCreator<out ViewDataBinding>
    ) {
        // empty layout
        if(data == RVBaseAdapter.EMPTY_ITEM){
            emptyViewHolder?.invoke()
            return
        }

        data ?: return

        viewHolder?.invoke(data as T,position,creator)
    }
}

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    RVBaseAdapter类的扩展

    fun buildAdapter(init: RVBaseAdapter.() -> Unit): RVBaseAdapter {
    return RVBaseAdapter().apply {
        init()
    }
}

inline fun <reified T : Any, V : ViewDataBinding> RVBaseAdapter.addItem(
    resourceID: Int,
    init: BaseViewHolderDSL<T, V>.() -> Unit
) {
    register(
        BaseViewHolderDSL<T, V>(resourceID, T::class).apply { init() }
    )
}

inline fun RVBaseAdapter.addEmptyView(
    resourceID: Int,
    init: (BaseViewHolderDSL<Any, LayoutEmptyBinding>.() -> Unit) = {}
) {
    register(
        BaseViewHolderDSL<Any, LayoutEmptyBinding>(resourceID, Any::class)
        .apply {
            init()
        },
        customViewType = RVBaseAdapter.VIEW_TYPE_EMPTY
    )

    setData(listOf(RVBaseAdapter.EMPTY_ITEM))
}

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    3.3 RecyclerView装饰绘制

    RecyclerView可以继承自ItemDecoration类绘制自己想要的分割线和装饰，这里做了几个例子，代码如下：

    3.3.1 以图片实现分割线

    /**
 * 分割线（以图片实现）
 */
class MyItemDecoration(divider: Drawable, dividerSize: Int) : 
RecyclerView.ItemDecoration() {
    private val mDivider = divider
    private val mDividerSize = dividerSize

    override fun onDraw(canvas: Canvas, parent: RecyclerView, state: 
    RecyclerView.State) {
        canvas.save()

        //居中显示
        val top = (parent.height - mDividerSize) / 2
        val bottom = top + mDividerSize

        val mBounds = Rect()

        //只在中间绘制
        for (i in 0 until parent.childCount - 1) {
            val child = parent.getChildAt(i)
            parent.layoutManager!!.getDecoratedBoundsWithMargins(child, mBounds)

            val right = mBounds.right + child.translationX.roundToInt()
            val left = right - mDividerSize
            mDivider.setBounds(left, top, right, bottom)
            mDivider.draw(canvas)
        }
        canvas.restore()
    }

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        outRect.set(0, 0, mDividerSize, 0)
    }
}

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    3.3.2 画网格线

    class ItemGridDecorationDrawable : ItemDecoration {
    private var leftRight: Int
    private var topBottom: Int
    private var mDivider: Drawable?

    constructor(spacePx: Int) {
        leftRight = spacePx
        topBottom = spacePx
        mDivider = ColorDrawable(Color.WHITE)
    }

    constructor(leftRight: Int, topBottom: Int) {
        this.leftRight = leftRight
        this.topBottom = topBottom
        mDivider = ColorDrawable(Color.WHITE)
    }

    constructor(leftRight: Int, topBottom: Int, mColor: Int) {
        this.leftRight = leftRight
        this.topBottom = topBottom
        mDivider = ColorDrawable(mColor)
    }

    override fun onDraw(
        c: Canvas,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        val layoutManager = parent.layoutManager 
        as GridLayoutManager? ?: return
        val lookup = layoutManager.spanSizeLookup
        if (mDivider == null || layoutManager.childCount == 0) {
            return
        }
        //判断总的数量是否可以整除
        val spanCount = layoutManager.spanCount
        var left: Int
        var right: Int
        var top: Int
        var bottom: Int
        val childCount = parent.childCount
        if (layoutManager.orientation == GridLayoutManager.VERTICAL) {
            for (i in 0 until childCount) {
                val child = parent.getChildAt(i)
                //将带有颜色的分割线处于中间位置
                val centerLeft =
                    ((layoutManager.getLeftDecorationWidth(child) + layoutManager.getRightDecorationWidth(
                        child
                    )).toFloat()
                            * spanCount / (spanCount + 1) + 1 - leftRight) / 2
                val centerTop =
                    (layoutManager.getBottomDecorationHeight(child)
                     + 1 - topBottom) / 2f
                //得到它在总数里面的位置
                val position = parent.getChildAdapterPosition(child)
                //获取它所占有的比重
                val spanSize = lookup.getSpanSize(position)
                //获取每排的位置
                val spanIndex = lookup.getSpanIndex(position, 
                layoutManager.spanCount)
                //判断是否为第一排
                val isFirst =
                    layoutManager.spanSizeLookup.getSpanGroupIndex(position,
                     spanCount) == 0
                //画上边的，第一排不需要上边的,只需要在最左边的那项的时候画一次就好
                if (!isFirst && spanIndex == 0) {
                    left = layoutManager.getLeftDecorationWidth(child)
                    right = parent.width - 
                    layoutManager.getLeftDecorationWidth(child)
                    top = (child.top - centerTop).toInt() - topBottom
                    bottom = top + topBottom
                    mDivider!!.setBounds(left, top, right, bottom)
                    mDivider!!.draw(c)
                }
                //最右边的一排不需要右边的
                val isRight = spanIndex + spanSize == spanCount
                if (!isRight) { //计算右边的
                    left = (child.right + centerLeft).toInt()
                    right = left + leftRight
                    top = child.top
                    if (!isFirst) {
                        top -= centerTop.toInt()
                    }
                    bottom = (child.bottom + centerTop).toInt()
                    mDivider!!.setBounds(left, top, right, bottom)
                    mDivider!!.draw(c)
                }
            }
        } else {
            for (i in 0 until childCount) {
                val child = parent.getChildAt(i)
                //将带有颜色的分割线处于中间位置
                val centerLeft =
                    (layoutManager.getRightDecorationWidth(child) 
                    + 1 - leftRight) / 2f
                val centerTop =
                    ((layoutManager.getTopDecorationHeight(child) + layoutManager.getBottomDecorationHeight(
                        child
                    )).toFloat()
* spanCount / (spanCount + 1) - topBottom) / 2
                //得到它在总数里面的位置
                val position = parent.getChildAdapterPosition(child)
                //获取它所占有的比重
                val spanSize = lookup.getSpanSize(position)
                //获取每排的位置
                val spanIndex = lookup
                .getSpanIndex(position, layoutManager.spanCount)
                //判断是否为第一列
                val isFirst =
                    layoutManager.spanSizeLookup
                    .getSpanGroupIndex(position, spanCount) == 0
                //画左边的，第一排不需要左边的,只需要在最上边的那项的时候画一次就好
                if (!isFirst && spanIndex == 0) {
                    left = (child.left - centerLeft).toInt() - leftRight
                    right = left + leftRight
                    top = layoutManager.getRightDecorationWidth(child)
                    bottom = parent.height - layoutManager.getTopDecorationHeight(child)
                    mDivider!!.setBounds(left, top, right, bottom)
                    mDivider!!.draw(c)
                }
                //最下的一排不需要下边的
                val isRight = spanIndex + spanSize == spanCount
                if (!isRight) { //计算右边的
                    left = child.left
                    if (!isFirst) {
                        left -= centerLeft.toInt()
                    }
                    right = (child.right + centerTop).toInt()
                    top = (child.bottom + centerLeft).toInt()
                    bottom = top + leftRight
                    mDivider!!.setBounds(left, top, right, bottom)
                    mDivider!!.draw(c)
                }
            }
        }
    }

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        val layoutManager = parent.layoutManager as GridLayoutManager? ?: return
        
        val lp =
            view.layoutParams as GridLayoutManager.LayoutParams
        val childPosition = parent.getChildAdapterPosition(view)
        val spanCount = layoutManager.spanCount
        if (layoutManager.orientation == GridLayoutManager.VERTICAL) { 
        //判断是否在第一排
            if (layoutManager.spanSizeLookup.getSpanGroupIndex(
                    childPosition,
                    spanCount
                ) == 0
            ) { //第一排的需要上面
                outRect.top = topBottom
            }
            outRect.bottom = topBottom
            //这里忽略和合并项的问题，只考虑占满和单一的问题
            if (lp.spanSize == spanCount) { //占满
                outRect.left = leftRight
                outRect.right = leftRight
            } else {
                outRect.left =
                    ((spanCount - lp.spanIndex).toFloat() / spanCount * leftRight).toInt()
                outRect.right =
                    (leftRight.toFloat() * (spanCount + 1) / spanCount - outRect.left).toInt()
            }
        } else {
            if (layoutManager.spanSizeLookup.getSpanGroupIndex(
                    childPosition,
                    spanCount
                ) == 0
            ) { //第一排的需要left
                outRect.left = leftRight
            }
            outRect.right = leftRight
            //这里忽略和合并项的问题，只考虑占满和单一的问题
            if (lp.spanSize == spanCount) { //占满
                outRect.top = topBottom
                outRect.bottom = topBottom
            } else {
                outRect.top =
                    ((spanCount - lp.spanIndex).toFloat() / spanCount * topBottom).toInt()
                outRect.bottom =
                    (topBottom.toFloat() * (spanCount + 1) / spanCount - outRect.top).toInt()
            }
        }
    }
}

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    3.3.3空白的分割线

    /**
 * 空白的分割线
 *
 */
class ItemDecorationSpace : ItemDecoration {
    private var top: Int
    private var left: Int
    private var right: Int
    private var bottom: Int
    private var spanCount: Int

    constructor(space: Int) : this(space, space, space, space)

    constructor(spaceLR: Int, spaceTB: Int) : this(spaceTB, spaceLR, spaceLR,
     spaceTB)

    constructor(top: Int, left: Int, right: Int, bottom: Int) {
        this.top = top
        this.left = left
        this.right = right
        this.bottom = bottom
        spanCount = 0
    }

    constructor(top: Int, left: Int, right: Int, bottom: Int, spanCount: Int) {
        this.top = top
        this.left = left
        this.right = right
        this.bottom = bottom
        this.spanCount = spanCount
    }

    override fun getItemOffsets(
        outRect: Rect, view: View,
        parent: RecyclerView, state: RecyclerView.State
    ) {
        outRect.top = top
        outRect.left = left
        outRect.bottom = bottom
        if (spanCount != 0) {
            val position = parent.getChildLayoutPosition(view)
            if ((position + 1) % spanCount == 0) {
                outRect.right = 0
            } else {
                outRect.right = right
            }
        } else {
            outRect.right = right
        }
    }
}

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    3.3.4 不同方向上的分割线

    /**
 * 不同方向上的分割线
 */

class ItemDecorationOrientation : ItemDecoration {
    private val dividerPx: Int
    private val headerPx: Int
    private val footerPx: Int
    private val orientation: Int

    constructor(dividerPx: Int, @RecyclerView.Orientation orientation: Int) 
    : this(
        dividerPx,
        dividerPx,
        orientation
    )

    constructor(
        dividerPx: Int,
        headerFooterPx: Int,
        @RecyclerView.Orientation orientation: Int
    ) : this(dividerPx, headerFooterPx, headerFooterPx, orientation)

    constructor(
        dividerPx: Int,
        headerPx: Int,
        footerPx: Int,
        @RecyclerView.Orientation orientation: Int
    ) {
        this.dividerPx = dividerPx
        this.headerPx = headerPx
        this.footerPx = footerPx
        this.orientation = orientation
    }

    override fun getItemOffsets(
        outRect: Rect,
        view: View,
        parent: RecyclerView,
        state: RecyclerView.State
    ) {
        if (orientation == RecyclerView.VERTICAL) {
            getItemOffsetsVertical(outRect, view, parent)
        } else {
            getItemOffsetsHorizontal(outRect, view, parent)
        }
    }

    private fun getItemOffsetsVertical(outRect: Rect, view: View,
     parent: RecyclerView) {
        val itemCount = parent.adapter?.itemCount ?: return
        val position = parent.getChildAdapterPosition(view)

        if (position == 0) {
            outRect.top = headerPx
        } else {
            outRect.top = position * dividerPx / itemCount
        }

        if (position == itemCount - 1) {
            outRect.bottom = footerPx
        } else {
            outRect.bottom = dividerPx - (position + 1) * dividerPx / itemCount
        }
    }

    private fun getItemOffsetsHorizontal(outRect: Rect, view: View, parent:
     RecyclerView) {
        val itemCount = parent.adapter?.itemCount ?: return
        val position = parent.getChildAdapterPosition(view)

        if (position == 0) {
            outRect.left = headerPx
        } else {
            outRect.left = position * dividerPx / itemCount
        }

        if (position == itemCount - 1) {
            outRect.right = footerPx
        } else {
            outRect.right = dividerPx - (position + 1) * dividerPx / itemCount
            
        }
    }
}

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    3.4 使用方法

    使用的时候去掉代码中对应的注释，体验各种风格

    class RecyclerViewActivity : AppCompatActivity() {
    private lateinit var dataBinding: ActivityRecyclerViewBinding
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        initDataBinding()
        initRV()
        val dataList = listOf<UserData>(
            UserData("walt zhong", 21),
            UserData("walt xian", 22),
            UserData("walt jian", 31),
            UserData("walt x", 22),
            UserData("walt y", 41),
            UserData("walt z", 26),
            UserData("walt 2", 29),
        )

        //   val dataList = emptyList()

        dataBinding.rvList.setData(dataList)
    }

    private fun initRV() {
        dataBinding.rvList.apply {
           // layoutManager = gridEmpty(3) //网格布局
            // layoutManager = vertical(false) // 垂直布局
             layoutManager = horizontal(false) // 水平布局
            adapter = buildAdapter {
                addEmptyView(R.layout.layout_empty)
                addItem<UserData, RvItemBinding>(R.layout.rv_item) {
                    initView { data, position, _ ->
                        itemDataBinding.apply {
                            tvName.text = data.name
                            tvAge.text = data.age.toString()

                            itemLayout.setOnClickListener {
                                Log.d("zhongxj", "click item: $position")
                            }
                        }
                    }
                }
            }

//            val pxValue = dp2px(5)
//
//            addItemDecoration(
//                ItemGridDecorationDrawable(
//                    pxValue,
//                    pxValue,
//                    R.color.purple_200
//                )
//            )

//            addItemDecoration(
//                ItemDecorationSpace(
//                    pxValue
//                )
//            )

//            addItemDecoration(
//                ItemDecorationOrientation(
//                   dividerPx = pxValue,
//                    headerFooterPx = 0,
//                    orientation = RecyclerView.HORIZONTAL
//                )
//            )

            val dividerSize = dp2px(16)
            val divider =  ContextCompat.getDrawable(context, R.drawable.ic_arrow)
            if(divider != null){
                addItemDecoration(
                    MyItemDecoration(
                        divider,
                        dividerSize
                    )
                )
            }
        }
    }

    private fun initDataBinding() {
        dataBinding = DataBindingUtil.setContentView(
            this,
            R.layout.activity_recycler_view
        )

        dataBinding.lifecycleOwner = this@RecyclerViewActivity
    }

    /**
     * 单位转换，将DP转为PX
     */
    fun dp2px(dpValue: Int): Int {
        val scale = Resources.getSystem().displayMetrics.density
        return (dpValue * scale + 0.5f).toInt()
    }
}

data class UserData(var name:String,var age:Int)

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    布局文件：
    RcyclerViewActivity布局

    
<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>

    data>
    <LinearLayout
        android:background="#eeeeee"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".RecyclerViewActivity">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/rv_list"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

    LinearLayout>
layout>

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    RecyclerView item布局

    
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>

    data>

    <LinearLayout
        android:background="@color/white"
        android:padding="10dp"
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:id="@+id/item_layout"
        >
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textSize="20sp"
            android:text="walt"
            android:id="@+id/tv_name"/>

        <TextView
            android:layout_marginTop="10dp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textSize="20sp"
            android:text="24"
            android:id="@+id/tv_age"/>

    LinearLayout>
layout>

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    没有数据时的空布局

    
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

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

        <ImageView
            android:id="@+id/empty_iv"
            android:layout_width="200dp"
            android:layout_height="200dp"
            android:src="@mipmap/ic_empty_data"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.382" />

        <TextView
            android:id="@+id/empty_tv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="5dp"
            android:text="没有数据"
            android:textColor="@color/black"
            android:textSize="16sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/empty_iv" />

    androidx.constraintlayout.widget.ConstraintLayout>
layout>

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    里面对应的图片读者自己找喜欢的替换上就可以啦，本文主要是记录，代码也不难，读者可以自行跟着敲一遍，加深映像，熟悉这种封装方法，后面可以使用在项目的其他部分的封装。

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  • 原文地址：https://blog.csdn.net/zxj2589/article/details/133442955