Android开发菜鸟——RecyclerView

RecyclerView整合了ListView和GridView两者的特性，即可以用RecyclerView替换这两者。

一、使用方法

1、布局使用RecyclerView

            itemCount、listitem只是为了预览而设置的，不是必须的。

2、设置列表格式layoutManager

网格列表recyclerView.layoutManager = GridLayoutManager(this, 3)线性列表recyclerView.layoutManager = LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false)瀑布列表recyclerView.layoutManager = StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL)

3、设置适配器adapter

recyclerView.adapter = RecycleAdapter()

二、通用Adapter

abstract class RecycleAdapter(private var mDataSet: ArrayList, private var listener: IRecyclerViewListener?): RecyclerView.Adapter() {// 按layoutResId保存holder    private var mHolders: SparseArray = SparseArray()    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecycleViewHolder {        var mHolder = getHolder(viewType)        if (mHolder == null) {        // 创建holder            mHolder = RecycleViewHolder.get(parent, getLayoutId(viewType))            putHolder(viewType, mHolder)        }        return mHolder    }    override fun getItemCount(): Int {        return mDataSet.size    }// 可以在此给列表项设置宽高    override fun onBindViewHolder(holder: RecycleViewHolder, position: Int) {        holder.itemView.setOnClickListener {            listener?.onItemClickListener(position)        }        holder.itemView.setOnLongClickListener {            listener?.onItemLongClickListener(position)            true        }        convert(holder, mDataSet[position], position)    }        private fun getHolder(viewType: Int): RecycleViewHolder? {        return mHolders.get(viewType)    }        private fun putHolder(viewType: Int, holder: RecycleViewHolder) {        mHolders.put(viewType, holder)    }        abstract fun getLayoutId(viewType: Int): Int        // 也可以在此给列表项设置宽高    abstract fun convert(holder: RecycleViewHolder, data: T, position: Int)}

三、常用配置

1、设置间隔

线性列表的间隔比较容易就不说了。

可添加多个间隔设置recyclerView.addItemDecoration()官方提供有DividerItemDecorationrecyclerView.addItemDecoration(DividerItemDecoration(context, orientation))间隔实现类：可组合实现多种效果class MyItemDecoration : RecyclerView.ItemDecoration() {    /**     * 设置padding：即设置Rect的left、top、right、bottom     */    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {       super.getItemOffsets(outRect, view, parent, state)    }    /**     * 绘制背景     * canvas可以绘制各种图形文字     */    override fun onDraw(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {        super.onDraw(c, parent, state)    }    /**     * 绘制遮罩     * canvas可以绘制各种图形文字     */    override fun onDrawOver(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {        super.onDrawOver(c, parent, state)    }}

2、设置网格列表项宽度不同占比

/** * A {@link RecyclerView.LayoutManager} implementations that lays out items in a grid. *  * By default, each item occupies 1 span. You can change it by providing a custom * {@link SpanSizeLookup} instance via {@link #setSpanSizeLookup(SpanSizeLookup)}. */public class GridLayoutManager extends LinearLayoutManager {}

通过官方代码注释可以看到，想要设置列表项占比，可以通过setSpanSizeLookup实现。以下是默认的SpanSizeLookup，可以看到列表项占比都是1，所以只需要覆写getSpanSize就行了

/**     * Default implementation for {@link SpanSizeLookup}. Each item occupies 1 span.     */    public static final class DefaultSpanSizeLookup extends SpanSizeLookup {        @Override        public int getSpanSize(int position) {            return 1;        }        @Override        public int getSpanIndex(int position, int spanCount) {            return position % spanCount;        }    }

四、自定义

RecycleView目前支持三种LayoutManager，如果这三种LayoutManager不能满足UI设计效果，可以通过自定义LayoutManager进行修改。