RecycleView的点击事件

原文：https://www.jianshu.com/p/8d5288b56f45

各实现方法以及存在的问题
想要实现RecyclerView的Item的点击事件，你可能会想到各种方法。
比如：
1.在创建ItemView时添加点击监听。
也就是在 RecyclerView.Adapter内的onBindViewHolder()直接实现绑定。
问题是“逻辑跟adapter类耦合严重”。
2.通过RecyclerView已有的方法addOnItemTouchListener()实现.
重载SimpleOnItemTouchListener类，用GestureDetectorCompat捕获item的点击事件。具体代Google一下即可。
问题是“子view不能获取点击”
依据“OnChildAttachStateChangeListener”实现点击监听
今天我们重点不在于前面这两种方法。而是要具体讲解一下第三种Item点击事件的实现。也就是依托于OnChildAttachStateChangeListener的实现。
目标：
1.足够优雅。
2.能够获取Item的点击，也能够实现子View的点击事件。
实现：
知道“OnChildAttachStateChangeListener”这个关键词，我们便可以Google一下此实现了。下面便是千篇一律的代码：

class ItemClickSupport private constructor(private val mRecyclerView: RecyclerView) {
    private var mOnItemClickListener: OnItemClickListener? = null
    private var mOnItemLongClickListener: OnItemLongClickListener? = null
    private val mOnClickListener = View.OnClickListener { v ->
        if (mOnItemClickListener != null) {
            val holder = mRecyclerView.getChildViewHolder(v)
            mOnItemClickListener!!.onItemClicked(mRecyclerView, holder.adapterPosition, v)
        }
    }
    private val mOnLongClickListener = View.OnLongClickListener { v ->
        if (mOnItemLongClickListener != null) {
            val holder = mRecyclerView.getChildViewHolder(v)
            return@OnLongClickListener mOnItemLongClickListener!!.onItemLongClicked(mRecyclerView, holder.adapterPosition, v)
        }
        false
    }
    private val mAttachListener = object : RecyclerView.OnChildAttachStateChangeListener {
        override fun onChildViewAttachedToWindow(view: View) {
            if (mOnItemClickListener != null) {
                view.setOnClickListener(mOnClickListener)
            }
            if (mOnItemLongClickListener != null) {
                view.setOnLongClickListener(mOnLongClickListener)
            }
        }

        override fun onChildViewDetachedFromWindow(view: View) {

        }
    }

    init {
        mRecyclerView.setTag(R.id.item_click_support, this)
        mRecyclerView.addOnChildAttachStateChangeListener(mAttachListener)
    }

    fun addOnItemClickListener(listener: OnItemClickListener): ItemClickSupport {
        mOnItemClickListener = listener
        return this
    }

    fun addOnItemLongClickListener(listener: OnItemLongClickListener): ItemClickSupport {
        mOnItemLongClickListener = listener
        return this
    }

    private fun detach(view: RecyclerView) {
        view.removeOnChildAttachStateChangeListener(mAttachListener)
        view.setTag(R.id.item_click_support, null)
    }

    // 点击接口
    public interface OnItemClickListener {
        fun onItemClicked(recyclerView: RecyclerView, position: Int, v: View)
    }

    // 长按接口
    interface OnItemLongClickListener {
        fun onItemLongClicked(recyclerView: RecyclerView, position: Int, v: View): Boolean
    }

    companion object {

        fun addTo(view: RecyclerView): ItemClickSupport {
            var support: ItemClickSupport? = view.getTag(R.id.item_click_support) as ItemClickSupport?
            if (support == null) {
                support = ItemClickSupport(view)
            }
            return support
        }

        fun removeFrom(view: RecyclerView): ItemClickSupport? {
            val support = view.getTag(R.id.item_click_support) as ItemClickSupport
            support.detach(view)
            return support
        }
    }
}

使用：
// 点击
      ItemClickSupport.addTo(recycler_view).addOnItemClickListener(object : ItemClickSupport.OnItemClickListener {
            override fun onItemClicked(recyclerView: RecyclerView, position: Int, v: View) {
                Snackbar.make(v, "recycler_view click", Snackbar.LENGTH_LONG).show()
            }

        })