以spinner舉例，首先定義一個(gè)在model

object SPModel : BaseObservable(){

    var pos = false

        @Bindable

        get(){

            return field

        }

        set(value){

            field = value

            notifyPropertyChanged(BR.pos)

        }

}

pos即spinner的selected position

然后給用BindingAdapter給spinner賦值

@JvmStatic

@BindingAdapter("selectedPos")

fun setSelectedPos(sp:Spinner,pos:Int){

    sp.setSelection(pos)

}

這個(gè)時(shí)候，當(dāng)我們修改model的pos的值的時(shí)候，spinner的選中項(xiàng)就會(huì)變成對(duì)應(yīng)position的項(xiàng)

然后需要對(duì)spinner進(jìn)行反向綁定，即用 Databinding對(duì)onItemSelectedListener進(jìn)行監(jiān)聽(tīng)

@JvmStatic

@InverseBindingAdapter(attribute = "selectedPos",event = "posAttrChanged")

fun getSelectedPos(sp:Spinner){

    return sp.selectedItemPosition

}

@JvmStatic

@BindingAdapter("posAttrChanged")

fun setSPChanged(sp:Spinner,lis:InverseBindingListener){

    sp.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {

        override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {

            lis.onChange()

        }

        override fun onNothingSelected(parent: AdapterView<*>?) { }

    }

}

這個(gè)BindingAdapter對(duì)應(yīng)的即是InverseBindingAdapter中的event，所以value需要與InverseBindingAdapter中的event一致

最后則是xml中添加屬性，根目錄添加 xmlns:bind="http://schemas.android.com/tools"

xmlns:bind="http://schemas.android.com/tools"

<Spinner
    android:layout_width = "300dp"

    android:layout_width = "60dp"

    android:entries = "@array/test"

    bind:selectedPos = "@={model.pos}"

/>