关于PopupWindow，首先要解决popupwindow在Android7.0显示错误的问题

open class PopupWindowV24 : PopupWindow {
    constructor(context: Context?) : super(context)
    constructor(context: Context?, attrs: AttributeSet?) : super(context, attrs)
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr)
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int, defStyleRes: Int) : super(context, attrs, defStyleAttr, defStyleRes)
    constructor() : super()
    constructor(contentView: View?) : super(contentView)
    constructor(width: Int, height: Int) : super(width, height)
    constructor(contentView: View?, width: Int, height: Int) : super(contentView, width, height)
    constructor(contentView: View?, width: Int, height: Int, focusable: Boolean) : super(contentView, width, height, focusable)

    override fun showAsDropDown(anchor: View) {
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.M) {
            val rect = Rect()
            anchor.getGlobalVisibleRect(rect)
            val h = anchor.resources.displayMetrics.heightPixels - rect.bottom
            height = h
        }
        super.showAsDropDown(anchor)
    }
}

WechatIMG14.jpeg

然后，我们需要先写一个类似京东地址选择的xml，因为radioGroup可以方便监听选择状态，而且可以复用recyclerview，

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">
    <!-- 阴影区 -->
    <View
        android:id="@+id/backgroundView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@color/black"
        android:alpha="0.5"
        <!-- 这里不是在titleCl而是tabRg是为了控制圆角效果 -->
        app:layout_constraintBottom_toTopOf="@id/tabRg"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
    <!-- 用来添加背景 -->
    <View
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@drawable/bg_popupwindow_radius"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@id/titleCl" />
    <!-- 顶部title和取消 -->
    <android.support.constraint.ConstraintLayout
        android:id="@+id/titleCl"
        android:layout_width="0dp"
        android:layout_height="65dp"
        android:layout_marginBottom="10dp"
        app:layout_constraintBottom_toTopOf="@id/tabRg"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <TextView
            android:id="@+id/titleTv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#333333"
            android:textSize="18dp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"/>

        <ImageView
            android:id="@+id/cancelTv"
            android:layout_width="20dp"
            android:layout_height="20dp"
            android:layout_marginEnd="20dp"
            android:gravity="center"
            android:paddingStart="20dp"
            android:paddingEnd="20dp"
            android:background="@drawable/close_drawable"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

    </android.support.constraint.ConstraintLayout>
    <!-- 选择器顶部的tab -->
    <RadioGroup
        android:id="@+id/tabRg"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toTopOf="@id/contentLl"
        app:layout_constraintStart_toStartOf="parent">

        <RadioButton
            android:id="@+id/firstRb"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_marginStart="20dp"
            android:button="@null"
            android:paddingTop="10dp"
            android:gravity="center_horizontal"
            android:text="请选择"
            android:maxLines="1"
            android:ellipsize="end"
            android:checked="true"
            android:textColor="#333333"
            android:textSize="13dp"
            tools:checked="true" />

        <RadioButton
            android:id="@+id/secondRb"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_marginStart="25dp"
            android:button="@null"
            android:maxLines="1"
            android:ellipsize="end"
            android:paddingTop="10dp"
            android:visibility="gone"
            android:gravity="center_horizontal"
            android:text="请选择"
            android:textColor="#333333"
            android:textSize="13dp" />

        <RadioButton
            android:id="@+id/thridRb"
            android:layout_marginStart="25dp"
            android:layout_width="wrap_content"
            android:button="@null"
            android:maxLines="1"
            android:visibility="gone"
            android:ellipsize="end"
            android:paddingTop="10dp"
            android:gravity="center_horizontal"
            android:text="请选择"
            android:textColor="#333333"
            android:textSize="13dp"
            android:layout_height="match_parent" />

    </RadioGroup>

    <android.support.constraint.ConstraintLayout
        android:id="@+id/contentLl"
        android:layout_width="0dp"
        android:layout_height="400dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/listItemRv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>

    </android.support.constraint.ConstraintLayout>
</android.support.constraint.ConstraintLayout>

分析一些三级选择器的参数，我们需要一个标题title，一个数据源dataSource，一个选择完成的回调，注意这里的数据源可以根据实际情况进行修改，不一定非要传三个list。

class ThirdLevelListPopupWindow(
        private val context: Context,
        private val title: String = "标题",
        private val dataSource: () -> ThirdLevelListDataModel,
        private val commitCallback: (param1: String,param2: Sting,param3: String) -> Unit
) : PopupWindowV24(context) {
    ...
}

分析一下这个三级列表的属性，首先，因为是三级列表，所以一定是每一级都依赖上一级的选择来进行联动，所以需要监听每次RecyclerView的点击位置。
同时，我们要根据点击的item来设置顶部tab的文字内容，所以需要在数据源中取出item中的数据，默认赋值为-1来表示初始化没有选择item的情况。

    private var firstList: ArrayList<String> = ArrayList()
    private var secondList: ArrayList<String> = ArrayList()
    private var thirdList: ArrayList<String> = ArrayList()

    private var firstIndex = -1
    set(value) {
        field = value
        if (value == -1) {
            firstRb.text = "请选择"
        } else {
            firstRb.text = firstList[value]
        }
    }

    private var secondIndex = -1
    set(value) {
        field = value
        if (value == -1) {
            secondRb.text = "请选择"
        } else {
            secondRb.text = secondList[value]
        }
    }


    private var thirdIndex = -1
    set(value) {
        field = value
        if (value == -1) {
            thirdRb.text = "请选择"
        } else {
            thirdRb.text = thirdList[value]
        }
    }

我们还需要一个标记来判断当前选中的tab：

private var curTabPosition : Int = 0

接下来我们要对RecyclerView的adapter进行设计，我们需要传入一个List数据源，一个选中位置的标记，还有一个选择item的点击闭包。
由于我们复用了同一个recyclerView，所以当我们选择不同tab的时候，要更改对应的数据源，需要在外部更改数据源、点击事件、和选择item的位置，所以我们用闭包来在外部控制数据。

class ThirdLevelListPopupWindowAdapter(
        private val dataSource : () -> List<String>,
        val isSelectedBlock: (Int) -> Boolean,
        val block: (Int) -> Unit)
: RecyclerView.Adapter<AddressListPopupWindowAdapter.ViewHolder>() {
    ...
}

其中item的点击事件在onBindViewHolder()中进行设置

        holder.itemView.setOnClickListener{
            block.invoke(position)
        }

在ThirdLevelListPopupWindow中初始化这个adapter：

adapter = ThirdLevelListPopupWindowAdapter({
            when (curTabPosition) {
                0 -> firstList
                1 -> secondList
                else -> thirdList
            }
        }, {
            when (curTabPosition) {
                0 -> it == firstIndex
                1 -> it == secondIndex
                else -> it == thirdIndex
            }
        },{
            when (curTabPosition) {
                0 -> setFirstTab(it)
                1 -> setSceondTab(it)
                else -> setThirdTab(it)
            }
        })

将adapter绑定到RecyclerView之后，为三个tab设置点击事件，

         firstRb.setOnClickListener {
            firstRb.isChecked = true
            curTabPosition = 0
            adapter.notifyDataSetChanged()
        }
        secondRb.setOnClickListener {
            secondRb.isChecked = true
            curTabPosition = 1
            adapter.notifyDataSetChanged()
        }
        thirdRb.setOnClickListener {
            thirdRb.isChecked = true
            curTabPosition = 2
            adapter.notifyDataSetChanged()
        }

每一级的RecyclerView的点击事件

    private fun setFirstTab(position: Int) {
        firstIndex = position
        firstRb.text = firstList[position]
        secondRb.visibility = View.VISIBLE
        secondRb.text = "请选择"
        secondIndex = -1
        secondRb.isChecked= true
        secondList.clear()
        initData(secondList)    //这里方法根据自己的实际情况去实现即可
        thirdIndex = -1
        thirdRb.visibility = View.GONE
        curTabPosition = 1
        adapter.notifyDataSetChanged()
    }

    private fun setSecondTab(position: Int) {
        curTabPosition = 2
        thirdIndex = -1
        thirdList.clear()
        initData(thirdList)
        thirdRb.visibility = View.VISIBLE
        thirdRb.isChecked = true
        thirdRb.text = "请选择"
        secondIndex = position
        adapter.notifyDataSetChanged()
    }

    private fun setSecondTab(position: Int) {
        thridIndex = position
        commitCallback.invoke(firstList[firstIndex], secondList[secondIndex], thirdList[thirdIndex])
        dismiss()
    }