RecycleView 项目中优化处理

RecycleView 我们在Android项目中经常使用，adapter一般我们是这么写的：显示新建一个Adapter类继承 RecyclerView.Adapter，然后
再写一个ViewHolder类继承RecyclerView.ViewHolder类

class JcActivityListAdapter(context: Context, list: List<JCActivityBean>) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

    var context = context
    var list = list
      lateinit var disposable: Disposable
    override fun getItemViewType(position: Int): Int {

        return if (position == 0) {
            ActivityConstant.TYPE_HEADER_VIEW
        } else {
            ActivityConstant.TYPE_NORMAL_VIEW
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): RecyclerView.ViewHolder {

        if (viewType == ActivityConstant.TYPE_HEADER_VIEW) {
            var headView = LayoutInflater.from(context).inflate(R.layout.group_buy_activity_head_layout, parent, false)
            return HeaderHolder(headView)
        } else {

            var view = LayoutInflater.from(context).inflate(R.layout.jc_activity_list_item_layout, parent, false)
            return ListHolder(view)
        }
    }

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

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder?, position: Int) {
   ...........省略业务代码
    }

    inner class ListHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        var image = itemView.findViewById(R.id.image) as SimpleDraweeView
        ...........省略业务代码
    }

    inner class HeaderHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

    }
}

这样的话，我们就会发现每次都要新建一个ViewHolder继承 RecyclerView.ViewHolder的匿名内部类，很是繁琐，

我们可以写一个公共ViewHolder类，把布局文件作为参数传进去 代码如下：

public class CustomViewHolder extends RecyclerView.ViewHolder {

    private SparseArray<View> views;
    private View rootView;

    public CustomViewHolder(View itemView) {
        super(itemView);
        views = new SparseArray<>();
        this.rootView = itemView;
    }

    public static CustomViewHolder createViewHolder(Context context, ViewGroup parent, int resource) {

        View rootView = LayoutInflater.from(context).inflate(resource, parent, false);
        CustomViewHolder customViewHolder = new CustomViewHolder(rootView);
        return customViewHolder;
    }
    public View getRootView() {
        return rootView;
    }

    public <T extends View> T getView(int resource) {

        View view = views.get(resource);
        if (view == null) {

            view = rootView.findViewById(resource);
            views.put(resource, view);
        }

        return (T) view;
    }

}

使用方式如下：

class DcGoodsListAdapter(context: Context,list: MutableList<CommdityBean>): RecyclerView.Adapter<CustomViewHolder>() {


    var context = context
    var list = list

    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): CustomViewHolder {

        return CustomViewHolder.createViewHolder(parent?.context,parent, R.layout.dc_goods_item_layout)

    }

    override fun getItemCount(): Int {

        return list.size
    }

    override fun onBindViewHolder(holder: CustomViewHolder?, position: Int) {

        (holder?.getView(R.id.commodity_name)as TextView).text = list[position].commodity_name
    //业务代码省略
    }


}