一种优雅的方式来使用RecyclerView

使得RecyclerView各种情况的多类型条目更简单！

示例图片

下载体验

核心思想

　　想必大家都遇到过，在一个列表中显示不同样式的需求。在RecyclerView中可以通过ViewType进行区分，如果样式特别多的时候就会使得代码非常冗余，不利于开发及维护。那么有没有一种优雅的方法解决这个问题呢？

　　技术经理给你说，接下来的项目由你负责，明天下班前把排期同步出来。这时你应该怎么做？由于你是Android端的RD，你对Android的排期是比较了解的，但是iOS端、FE端、Server端的排期怎么办呢？聪明的你立即把任务派发下去了，给每个端的负责人说，明天中午之前把排期汇总给我。

　　没错，在多样式列表的设计中也可以采用这种策略，给RecyclerView设置的Adapter不做具体的处理，而是由它派发出去。

实现方案

1. addDelegate 向Adapter中注册委托Adapter;
2. addDataList 设置数据；
3. layout 渲染布局，Adapter查找到对应的委托Adapter，由委托Adapter去做具体渲染。

引入

androidX

implementation 'com.kevin:delegationadapter:2.0.4'
// 扩展库，扩展支持了item click、item long click、databinding、load more
implementation 'com.kevin:delegationadapter-extras:2.0.4'

support

implementation 'com.kevin:delegationadapter:1.2.1'
// 扩展库，扩展支持了item click、item long click、databinding、load more
implementation 'com.kevin:delegationadapter-extras:1.2.1'

如何使用

简单用法

1. 带RecyclerView的布局

   <?xml version="1.0" encoding="utf-8"?>
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:layout_width="match_parent"
       android:layout_height="match_parent">
   
       <android.support.v7.widget.RecyclerView
           android:id="@+id/recycler_view"
           android:layout_width="match_parent"
           android:layout_height="match_parent" />
   
   </LinearLayout>
   

2. 初始化RecyclerView

   Adapter为DelegationAdapter，然后向DelegationAdapter中注册委托Adapter。

   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       RecyclerView recyclerView = findViewById(R.id.recycler_view);
       // ① 设置 LayoutManager
       // LinearLayoutManager layoutManager = new LinearLayoutManager(this);
       GridLayoutManager layoutManager = new GridLayoutManager(this, 3);
       recyclerView.setLayoutManager(layoutManager);
       // ② 创建 DelegationAdapter 对象
       DelegationAdapter delegationAdapter = new DelegationAdapter();
       // ③ 向Adapter中注册委托Adapter
       delegationAdapter.addDelegate(new CompanyAdapterDelegate());
       // ④ 设置Adapter
       recyclerView.setAdapter(delegationAdapter);
   }
   

3. 委托Adapter编写

   委托Adapter继承自AdapterDelegate，需要两个泛型，第一个为该委托Adapter可处理数据的数据类型(这里为String)，第二个参数为ViewHolder。剩下的就按照之前怎么写Adapter来写委托Adapter就可以啦。比如：在onCreateViewHolder创建ViewHolder，在onBindViewHolder中绑定数据到视图控件。

   public class CompanyAdapterDelegate extends AdapterDelegate<String, CompanyAdapterDelegate.ViewHolder> {
   
       @Override
       public ViewHolder onCreateViewHolder(ViewGroup parent) {
           View view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
           ViewHolder holder = new ViewHolder(view);
           return holder;
       }
   
       @Override
       public void onBindViewHolder(final ViewHolder holder, final int position, final String item) {
           holder.tvName.setText(item);
       }
   
       static class ViewHolder extends RecyclerView.ViewHolder {
           public TextView tvName;
   
           public ViewHolder(View itemView) {
               super(itemView);
               tvName = itemView.findViewById(android.R.id.text1);
           }
       }
   }
   

4. 设置数据

   protected void onCreate(Bundle savedInstanceState) {
       // ... ...
   
       List<String> companies = new ArrayList<>();
       companies.add("🇨🇳 Baidu");
       companies.add("🇨🇳 Alibaba");
       companies.add("🇨🇳 Tencent");
       companies.add("🇺🇸 Google");
       companies.add("🇺🇸 Facebook");
       companies.add("🇺🇸 Microsoft");
       // ⑤ 设置数据
       delegationAdapter.setDataItems(companies);
   }
   

复杂用法

如果想区分🇨🇳公司为红色，美国公司为蓝色，怎么办呢？

1. 编写CNCompanyAdapterDelegate

   public class CNCompanyAdapterDelegate extends AdapterDelegate<String, CNCompanyAdapterDelegate.ViewHolder> {
   
       @Override
       public boolean isForViewType(String item, int position) {
           return item.contains("🇨🇳");
       }
   
       @Override
       public ViewHolder onCreateViewHolder(ViewGroup parent) {
           View view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
           ViewHolder holder = new ViewHolder(view);
           return holder;
       }
   
       @Override
       public void onBindViewHolder(final ViewHolder holder, final int position, final String item) {
           holder.tvName.setText(item);
           holder.tvName.setTextColor(Color.RED);
       }
       
       static class ViewHolder extends RecyclerView.ViewHolder {
           public TextView tvName;
   
           public ViewHolder(View itemView) {
               super(itemView);
               tvName = itemView.findViewById(android.R.id.text1);
           }
       }
   }
   

2. 编写USCompanyAdapterDelegate

   public class USCompanyAdapterDelegate extends AdapterDelegate<String, USCompanyAdapterDelegate.ViewHolder> {
   
       @Override
       public boolean isForViewType(String item, int position) {
           return item.contains("🇺🇸");
       }
   
       @Override
       public ViewHolder onCreateViewHolder(ViewGroup parent) {
           View view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
           ViewHolder holder = new ViewHolder(view);
           return holder;
       }
   
       @Override
       public void onBindViewHolder(final ViewHolder holder, final int position, final String item) {
           holder.tvName.setText(item);
           holder.tvName.setTextColor(Color.BLUE);
       }
   
       static class ViewHolder extends RecyclerView.ViewHolder {
           public TextView tvName;
   
           public ViewHolder(View itemView) {
               super(itemView);
               tvName = itemView.findViewById(android.R.id.text1);
           }
       }
   }
   

3. 注册委托Adapter

// 向Adapter中注册委托Adapter
delegationAdapter.addDelegate(new CNCompanyAdapterDelegate());
delegationAdapter.addDelegate(new USCompanyAdapterDelegate());

更多请看示例

THANKS TO

1. MultiItem 委托思想来源
2. AdapterDelegates 委托架子来源