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关于在MVVM框架中BaseRecyclerViewAdapter的封装

在Android Studio 4.0及之后版本中，黄油刀（butter knife）因不适配AndroidX库而逐渐退出舞台，官方也发布公告称将不再继续支持。这意味着开发者需要重新考虑数据绑定相关的布局和Adapter封装方式。在此背景下，建议使用官方提供的ViewDataBinding来进行RecyclerView Adapter的封装和优化。本文将介绍如何将现有的YellowButterknife代码重新转型为ViewDataBinding的应用，并在此基础上对RecyclerView Adapter进行封装和拓展。

作为一名开发者，我决定重新对RecyclerView的Adapter进行封箱与优化，解决以下问题：

封装后的代码效果

通过封装后代码的简洁性，可以看出这种方式对开发者来说更加高效和便捷。例如，常规的Adapter类可以像下面这样的代码展示：

class JokeAdapter(context: Context) :    BaseRecyclerViewAdapter
   
     {    override fun getLayoutId(): Int {        return R.layout.joke_item    }    override fun onBindHolder(        holder: BaseViewHolder
    
     ,        position: Int    ) {        holder.getBinding().setItem(mList.get(position))    }}
    
   

从代码中可以看出，开发者只需要继承BaseRecyclerViewAdapter，并提供相应的数据类型和布局即可，实现起来更加简洁高效。

BaseRecyclerViewAdapter的实现

BaseRecyclerViewAdapter 是我们的核心基类，主要功能包括：

BaseViewHolder的实现

ViewHolder 的封装是 BaseRecyclerViewAdapter 的重要组成部分，它负责管理和操作每个RecyclerView项的绑定和刷新。BaseViewHolder 的实现如下：

class BaseViewHolder
   
     :    RecyclerView.ViewHolder {    private val binding: T    private val headerBinding: ViewDataBinding? = null    private val isHeaderViewHolder: Boolean = false    constructor(binding: T) : super(binding.root) {        this.binding = binding    }    constructor(headerBinding: ViewDataBinding, isHeaderViewHolder: Boolean) :        super(headerBinding.root) {        this.isHeaderViewHolder = isHeaderViewHolder        this.headerBinding = headerBinding        this.binding = null    }    fun getBinding(): T = binding    fun getHeaderBinding(): ViewDataBinding? = headerBinding}
   

点击事件与长按事件的封装

交互功能是使用BaseRecyclerViewAdapter 的重要体现，通过在onBindViewHolder方法中添加点击事件和长按事件处理，用户可以在RecyclerView列表中实现单项交互。

完整代码

以下是完整的代码示例，展示了BaseRecyclerViewAdapter以及其相关辅助类的实现：

package com.jcloudsoft.demo.baseimport android.content.Contextimport android.view.LayoutInflaterimport android.view.Viewimport android.view.ViewGroupimport androidx.annotation.LayoutResimport androidx.databind.BinaryOperatorimport androidx.databinding.DataBindingUtilimport androidx.databinding.ViewDataBindingimport androidx.recyclerview.widget.RecyclerViewimport java.util.*abstract class BaseRecyclerViewAdapter
   
     :    RecyclerView.Adapter
    
     
      >,    SimpleItemTouchHelperCallback.ItemTouchHelperAdapter {    protected var mContext: Context    protected var mList: List
      
        = ArrayList()    protected var headerView: View? = null    private var headerViewId: Int = -1    companion object {        const val TYPE_HEAD = 1        const val TYPE_NORMAL = 0    }    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BaseViewHolder
       
         {        if (viewType == TYPE_HEAD && headerViewId != -1) {            val binding = DataBindingUtil.inflate(                LayoutInflater.from(parent.context),                headerViewId,                parent,                false            )            return BaseViewHolder(binding, true)        }        val binding = DataBindingUtil.inflate(            LayoutInflater.from(parent.context),            getLayoutId(),            parent,            false        )        return BaseViewHolder(binding)    }    override fun onBindViewHolder(holder: BaseViewHolder
        
         , position: Int) { if (headerView == null) { if (position == 0) { return } } if (getItemViewType(position) == TYPE_HEAD) { onBindHeaderHolder(holder, getRealPosition(holder)) return } holder.getBinding().root.setOnClickListener { v -> if (mOnItemClickListener != null) { mOnItemClickListener.onItemClick(v, getRealPosition(holder)) } } holder.getBinding().root.setLongClickable { v -> if (mOnItemLongClickListener != null) { mOnItemLongClickListener.onItemLongClick(v, getRealPosition(holder)) true } false } onBindHolder(holder, getRealPosition(holder)) } protected abstract val mList: List
         
           protected abstract val layoutId: Int @LayoutRes get protected abstract fun onBindHolder(holder: BaseViewHolder
          
           , position: Int) protected abstract fun onBindHeaderHolder(holder: BaseViewHolder
           
            , position: Int) // ... 其他方法}
           
          
         
        
       
      
     
    
   

BaseViewHolder的实现

package com.jcloudsoft.demo.baseimport android.view.LayoutInflaterimport android.view.Viewimport android.view.ViewGroupimport androidx.databinding.ViewDataBindingimport androidx.recyclerview.widget.RecyclerViewclass BaseViewHolder
   
     : RecyclerView.ViewHolder {    private val binding: T    private val headerBinding: ViewDataBinding? = null    private val isHeaderViewHolder: Boolean = false    constructor(binding: T) : super(binding.root) {        this.binding = binding    }    constructor(headerBinding: ViewDataBinding, isHeaderViewHolder: Boolean) :        super(headerBinding.root) {        this.isHeaderViewHolder = isHeaderViewHolder        this.headerBinding = headerBinding        this.binding = null    }    fun getBinding(): T = binding    fun getHeaderBinding(): ViewDataBinding? = headerBinding    // ... 其他属性和方法}
   

通过上述封装，我们可以更灵活地处理RecyclerView列表，支持多种布局模式和交互功能，同时提高代码的可维护性和可读性。

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