RecyclerView之Header和Footer的添加

一，添加Header和Footer

在Adapter中新添加一些int值，用于區(qū)分添加Header，F(xiàn)ooter，還是都沒有添加

        val TYPE_FOOTER = 1//添加Footer
        val TYPE_HEADER = 2//添加Header
        val TYPE_NORMAL = 0//兩者都沒有添加

在Adapter中新暴漏兩個方法，用于設(shè)置Header和Footer

    fun setHeaderView(hv: View){
        headerView = hv
        notifyItemInserted(0)
    }

    fun setFooterView(fv: View){
        footerView = fv
        notifyItemInserted(itemCount - 1)
    }

根據(jù)是否添加了Header和Footer來設(shè)置itemCount的值

    override fun getItemCount(): Int{
        if (headerView != null && footerView != null)
            return items.size + 2
        else if(headerView == null && footerView == null)
            return items.size
        else
            return items.size + 1
    }

復(fù)寫getItemViewType方法，用于區(qū)分是否需要添加Header和Footer

    override fun getItemViewType(position: Int): Int {
        if (headerView == null && footerView == null)
            return TYPE_NORMAL
        if(position == 0)
            return TYPE_HEADER
        if(position == itemCount-1)
            return TYPE_FOOTER
        return TYPE_NORMAL
    }

在onCreateViewHolder中根據(jù)設(shè)置的標(biāo)記來分別綁定布局文件

    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ViewHolder {
        if (headerView != null && viewType == TYPE_HEADER)
            return ViewHolder(headerView!!)
        if (footerView != null && viewType == TYPE_FOOTER)
            return ViewHolder(footerView!!)

        val view = LayoutInflater.from(context).inflate(R.layout.item_rc_4st, parent, false)
        view.setOnClickListener { view ->  listener?.onItemClick(view, view.tag as Int) }
        return ViewHolder(view)
    }

或者寫成

override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ViewHolder {
        if (headerView != null && viewType == TYPE_HEADER) {
            val view = LayoutInflater.from(context).inflate(R.layout.header, parent, false)
            return ViewHolder(view)      
        }
        if (footerView != null && viewType == TYPE_FOOTER) {
            val view = LayoutInflater.from(context).inflate(R.layout.footer, parent, false)
            return ViewHolder(view)
        }
        val view = LayoutInflater.from(context).inflate(R.layout.item_rc_4st, parent, false)
        view.setOnClickListener { view ->  listener?.onItemClick(view, view.tag as Int) }
        return ViewHolder(view)
    }

在onBindViewHolder增加多Footer和Header的處理。如果添加了Header的話，那么Header的位置為‘0’，此時pos位置的值為數(shù)據(jù)中pos-1位置的值

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        if (getItemViewType(position) == TYPE_HEADER) return
        else if (getItemViewType(position) == TYPE_FOOTER) return
        else{
            if (holder is RecyclerViewAddHeaderAndFooterAdapter.ViewHolder){
                Log.e("hjd", "position->"+ position)
                val positionTemp = if (headerView == null) position else position -1//計算pos位置
                if (positionTemp < items.size){
                    holder.tv!!.text = items[positionTemp]
                    holder.itemView.tag= positionTemp
                }
            }
        }
    }

這樣添加Header和Footer就完成了，下面來看Adapter中的完整代碼

class RecyclerViewAddHeaderAndFooterAdapter(var context: Context, var items: ArrayList<String>):RecyclerView.Adapter<RecyclerViewAddHeaderAndFooterAdapter.ViewHolder>(){
    companion object{
        val TYPE_FOOTER = 1//添加Footer
        val TYPE_HEADER = 2//添加Header
        val TYPE_NORMAL = 0//兩者都沒有添加
        var headerView: View? = null
        var footerView: View? = null
    }
    var list = ArrayList<String>()
    init {
        list = items
    }

    fun setHeaderView(hv: View){
        headerView = hv
        notifyItemInserted(0)
    }

    fun setFooterView(fv: View){
        footerView = fv
        notifyItemInserted(itemCount - 1)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        if (getItemViewType(position) == TYPE_HEADER) return
        else if (getItemViewType(position) == TYPE_FOOTER) return
        else{
            if (holder is RecyclerViewAddHeaderAndFooterAdapter.ViewHolder){
                Log.e("hjd", "position->"+ position)
                val positionTemp = if (headerView == null) position else position -1
                if (positionTemp < items.size){
                    holder.tv!!.text = items[positionTemp]
                    holder.itemView.tag= positionTemp
                }
            }
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ViewHolder {
        if (headerView != null && viewType == TYPE_HEADER)
            return ViewHolder(headerView!!)
        if (footerView != null && viewType == TYPE_FOOTER)
            return ViewHolder(footerView!!)

        val view = LayoutInflater.from(context).inflate(R.layout.item_rc_4st, parent, false)
        view.setOnClickListener { view ->  listener?.onItemClick(view, view.tag as Int) }
        return ViewHolder(view)
    }

    override fun getItemCount(): Int{
        if (headerView != null && footerView != null)
            return items.size + 2
        else if(headerView == null && footerView == null)
            return items.size
        else
            return items.size + 1
    }

    override fun getItemViewType(position: Int): Int {
        if (headerView == null && footerView == null)
            return TYPE_NORMAL
        if(position == 0)
            return TYPE_HEADER
        if(position == itemCount-1)
            return TYPE_FOOTER
        return TYPE_NORMAL
    }

    class ViewHolder(itemTv: View):RecyclerView.ViewHolder(itemTv){
        var tv: TextView? = null

        init {
            if (headerView != itemTv && footerView != itemTv) {
                tv = itemTv.findViewById(R.id.tv) as TextView
            }
        }

    }


    private var listener: OnItemClickListener?=null

    fun setOnItemClickListener(l: OnItemClickListener): Unit{
        this.listener = l
    }
    interface OnItemClickListener{
        fun onItemClick(view: View, pos: Int)
    }

    fun addItem(pos: Int){
        list.add(pos, "Add item"+ pos)
        notifyItemInserted(pos)
    }

    fun delItem(pos: Int){
        list.removeAt(pos)
        notifyItemRemoved(pos)
    }
}

因為我沒有在上面的Adapter中直接設(shè)置Header和Footer的布局，因此需要在Activity中進行設(shè)置

    /**
     * 添加HeaderView
     */
    fun setHeaderView(rv: RecyclerView, adapter: RecyclerViewAddHeaderAndFooterAdapter){
        val hv = LayoutInflater.from(this).inflate(R.layout.header, rv, false)
        adapter.setHeaderView(hv)
    }

    /**
     * 添加FooterView
     */
    fun setFooterView(rv: RecyclerView, adapter: RecyclerViewAddHeaderAndFooterAdapter){
        val hv = LayoutInflater.from(this).inflate(R.layout.footer, rv, false)
        adapter.setFooterView(hv)
    }

效果圖如下


device-2017-06-27-094800.png

上面效果使用的顯示方式為LinearLayoutManager，現(xiàn)在換成GridLayoutManager，運行，效果圖為：

device-2017-06-27-101049.png

可以看出，Header和Footer都只是占據(jù)了一個Item的位置，而我們希望的是占據(jù)一行，所以這樣明顯不符合我們的要求。在GridLayoutManager中提供了setSpanSizeLookup方法，它就是用來設(shè)置列數(shù)的，我們可以通過調(diào)用此方法來滿足我們的要求。
在Adapter中，復(fù)寫onAttachedToRecyclerView方法

//此為Kotlin代碼
override fun onAttachedToRecyclerView(recyclerView: RecyclerView?) {
        val manager = recyclerView!!.layoutManager
        if (manager == null){
            Log.e("hjd", "layoutManager == null")
        }else {
            if (manager is GridLayoutManager) {
                val glm: GridLayoutManager = manager
                glm.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup() {
                    override fun getSpanSize(position: Int): Int {
                        if (getItemViewType(position) == TYPE_HEADER || getItemViewType(position) == TYPE_FOOTER)
                            return glm.spanCount
                        else
                            return 1
                    }
                }
            }
        }
    }

//此為Java代碼
@Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        if (layoutManager == null){
            Log.e("hjd", "layoutManager == null");
        }else {
            if (layoutManager instanceof GridLayoutManager){
                final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
                gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
                    @Override
                    public int getSpanSize(int position) {
                        if (getItemViewType(position) == TYPE_FOOTER || getItemViewType(position) == TYPE_HEADER)
                            return gridLayoutManager.getSpanCount();
                        else
                            return 1;
                    }
                });
            }
        }
    }

運行程序，發(fā)現(xiàn)上面的Kotlin代碼并沒有實現(xiàn)，我們的效果。而
Java代碼能夠正確實現(xiàn)我們的效果，圖為：

device-2017-06-27-143323.png

當(dāng)然也并不是只能在Adapter中進行設(shè)置，也可以直接在Activity中進行：

//此為Kotlin代碼
gridLayoutManager.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup(){
            override fun getSpanSize(position: Int): Int {
                if (mAdapter!!.getItemViewType(position) == 1 || mAdapter!!.getItemViewType(position) == 2){
                    return gridLayoutManager.spanCount
                }else
                    return 1
            }
        }

上面兩種代碼都可以實現(xiàn)上圖效果。
現(xiàn)在換成StaggeredGridLayoutManager，運行，效果圖為：

device-2017-06-27-101049.png

也只是占用一個Item的位置，因此我們也要進行配置，以滿足我們的要求

//此為Kotlin代碼
    override fun onViewAttachedToWindow(holder: ViewHolder?) {
        super.onViewAttachedToWindow(holder)
        val layoutParams = holder!!.itemView.layoutParams
        if (layoutParams != null && layoutParams is StaggeredGridLayoutManager.LayoutParams) {
            layoutParams.isFullSpan = getItemViewType(holder.layoutPosition) == TYPE_HEADER || getItemViewType(holder.layoutPosition) == TYPE_FOOTER
        }
    }

//此為Java代碼
@Override
    public void onViewAttachedToWindow(ViewHodler holder) {
        super.onViewAttachedToWindow(holder);
        ViewGroup.LayoutParams layoutParams = holder.itemView.getLayoutParams();
        if (layoutParams != null && layoutParams instanceof StaggeredGridLayoutManager.LayoutParams){
            StaggeredGridLayoutManager.LayoutParams lp = (StaggeredGridLayoutManager.LayoutParams) layoutParams;
            lp.setFullSpan(getItemViewType(holder.getLayoutPosition())== TYPE_HEADER || getItemViewType(holder.getLayoutPosition()) == TYPE_FOOTER);
        }
    }

運行程序，效果圖為：


device-2017-06-27-152155.png

這樣RecyclerView中三種顯示方式，都能正確顯示Header和Footer。
好了，RecyclerView添加Header和Footer就介紹到這里，不足之處請各位指正，謝謝。下一篇講解RecyclerView之上拉加載下拉刷新

參考文章

最后編輯于 ：
?著作權(quán)歸作者所有,轉(zhuǎn)載或內(nèi)容合作請聯(lián)系作者
【社區(qū)內(nèi)容提示】社區(qū)部分內(nèi)容疑似由AI輔助生成，瀏覽時請結(jié)合常識與多方信息審慎甄別。
平臺聲明：文章內(nèi)容（如有圖片或視頻亦包括在內(nèi)）由作者上傳并發(fā)布，文章內(nèi)容僅代表作者本人觀點，簡書系信息發(fā)布平臺，僅提供信息存儲服務(wù)。

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容