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**

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？

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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

addDelegate 向Adapter中注册委托Adapter;
addDataList 设置数据；
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

implementation 'com.kevin:delegationadapter:1.1.7'
// 扩展库，扩展支持了item click、item long click、databinding、load more
implementation 'com.kevin:delegationadapter-extras:1.1.7'

如何使用

简单用法

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>

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);
}

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);
        }
    }
}

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？

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);
        }
    }
}

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);
        }
    }
}

注册委托Adapter

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

THANKS TO

MultiItem 委托**来源
AdapterDelegates 委托架子来源

tonicus/DelegationAdapter