安卓中RecyclerView的嵌套问题-零点诗人的博客

一、使用情景分析

在有些时候，我们需要嵌套使用RecyclerView才能恰当的构建布局，比如在下方的墨刀项目中，对于购物车界面就需要使用RecyclerView进行嵌套。

游戏交易平台项目中的购物界面，首先为保证底栏，上方内容都放置于Fragment中，中间区域的商店利用RecyclerView进行加载。

外层布局分析

外层为商店信息，主要有以下控件需要根据数据动态加载：

信息	控件
商店复选框	CheckBox
店铺图标	imageView
店铺名称	TextView
商品数据	RecyclerView

内层布局分析

内层为用户添加的要购买的商品信息，主要有以下控件需要动态加载：

信息	控件
货品复选框	CheckBox
货品图片	ImageView
货品标题	TextView
发货方式	TextView
货品单价	TextView
数量	TextView组合

二、布局代码

布局不是本文重点，参考下方代码即可，不过多赘述。

外层布局代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="10dp"
    android:padding="10dp"
    app:cardCornerRadius="10dp">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <CheckBox
            android:id="@+id/shopCheckBox"
            style="@style/Widget.AppCompat.CompoundButton.RadioButton"
            android:layout_width="30dp"
            android:layout_height="wrap_content"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <ImageView
            android:id="@+id/imageView30"
            android:layout_width="20dp"
            android:layout_height="20dp"
            android:layout_marginStart="8dp"
            app:layout_constraintBottom_toBottomOf="@+id/shopCheckBox"
            app:layout_constraintStart_toEndOf="@+id/shopCheckBox"
            app:layout_constraintTop_toTopOf="@+id/shopCheckBox"
            app:srcCompat="@drawable/shopcar_shop_icon" />

        <TextView
            android:id="@+id/shopname"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="8dp"
            android:text="TextView"
            app:layout_constraintBottom_toBottomOf="@+id/imageView30"
            app:layout_constraintStart_toEndOf="@+id/imageView30"
            app:layout_constraintTop_toTopOf="@+id/imageView30" />

        <ImageView
            android:id="@+id/imageView31"
            android:layout_width="24dp"
            android:layout_height="24dp"
            android:layout_marginStart="8dp"
            app:layout_constraintBottom_toBottomOf="@+id/shopname"
            app:layout_constraintStart_toEndOf="@+id/shopname"
            app:layout_constraintTop_toTopOf="@+id/shopname"
            app:srcCompat="@drawable/right_arrow" />

        <TextView
            android:id="@+id/textView46"
            android:layout_width="match_parent"
            android:layout_height="1dp"
            android:background="@color/theme_gray"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/shopCheckBox" />

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/shopGoodRecyclerView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="10dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/textView46" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>

内层布局代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <CheckBox
        android:id="@+id/ShopCarGoodCheckBox"
        style="@style/Widget.AppCompat.CompoundButton.RadioButton"
        android:layout_width="30dp"
        android:layout_height="60dp"
        android:clickable="true"
        app:layout_constraintBottom_toBottomOf="@+id/ShopCarGoodImg"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/ShopCarGoodImg" />

    <ImageView
        android:id="@+id/ShopCarGoodImg"
        android:layout_width="60dp"
        android:layout_height="60dp"
        app:layout_constraintStart_toEndOf="@+id/ShopCarGoodCheckBox"
        app:layout_constraintTop_toTopOf="parent"
        app:srcCompat="@drawable/goods_gameitem" />

    <TextView
        android:id="@+id/ShopCarGoodTitle"
        android:layout_width="212dp"
        android:layout_height="40dp"
        android:layout_marginStart="16dp"
        android:text="TextView"
        app:layout_constraintStart_toEndOf="@+id/ShopCarGoodImg"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/ShopCarGoodShippingForm"
        android:layout_width="108dp"
        android:layout_height="16dp"
        android:text="TextView"
        android:textColor="@color/text_gray"
        android:textSize="12sp"
        app:layout_constraintStart_toStartOf="@+id/ShopCarGoodTitle"
        app:layout_constraintTop_toBottomOf="@+id/ShopCarGoodTitle" />

    <TextView
        android:id="@+id/ShopCarGoodPrice"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="TextView"
        android:textColor="@color/theme_red"
        android:textSize="16sp"
        android:textStyle="bold"
        app:layout_constraintStart_toStartOf="@+id/ShopCarGoodShippingForm"
        app:layout_constraintTop_toBottomOf="@+id/ShopCarGoodShippingForm" />

    <com.dreamgyf.android.ui.widget.shape.ShapeLayout
        android:layout_width="78dp"
        android:layout_height="22dp"
        app:cornerRadius="4dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="@+id/ShopCarGoodPrice"
        app:strokeColor="@color/text_light_gray"
        app:strokeWidth="1dp">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <com.dreamgyf.android.ui.widget.shape.ShapeLayout
                android:layout_width="22dp"
                android:layout_height="match_parent"
                app:cornerBottomLeftRadius="4dp"
                app:cornerTopLeftRadius="4dp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                app:strokeColor="@color/text_light_gray"
                app:strokeWidth="1dp">

                <TextView
                    android:id="@+id/textView40"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:gravity="center"
                    android:text="-" />
            </com.dreamgyf.android.ui.widget.shape.ShapeLayout>

            <TextView
                android:id="@+id/ShopCarGoodNumbers"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginStart="22dp"
                android:layout_marginEnd="22dp"
                android:gravity="center"
                android:text="0"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent" />

            <com.dreamgyf.android.ui.widget.shape.ShapeLayout
                android:layout_width="22dp"
                android:layout_height="match_parent"
                app:cornerBottomRightRadius="4dp"
                app:cornerTopRightRadius="4dp"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                app:strokeColor="@color/text_light_gray"
                app:strokeWidth="1dp">

                <TextView
                    android:id="@+id/textView42"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:gravity="center"
                    android:text="+" />
            </com.dreamgyf.android.ui.widget.shape.ShapeLayout>
        </androidx.constraintlayout.widget.ConstraintLayout>

    </com.dreamgyf.android.ui.widget.shape.ShapeLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

三、Java代码

使用RecyclerView通常需要三步：

编写Holder
编写Adaptor
为RecyclerView对象设置Adaptor和布局

为了使得体系更加清晰明了，我们把Holder作为Adaptor的内部类。

问题分析

在Adaptor onBindViewHolder()方法中，需要给holder中注册过的部件设置值，每一个商店都有自己的值和嵌套的RecyclerView，每个内层RecyclerView中又都需要详细的信息，他们大概都是不同的。往常我们往往把数据设置为全局变量以方便访问，但内层数据有多个且输入不确定，内层布局中的数据该如何获取呢？

数据的解决方法

跟布局类似，我们需要把内层数据嵌套进外层数据中，并且在创建Adaptor时作为其私有属性传入，这样就把每个RecyclerView的数据绑定进其对应的Adaptor中。

为节省版面略去基础方法

内层数据实体类

public class ShopCarGoodItem {
    private boolean selected;
    private String imgUrl;
    private String title;
    private String ShippingForm;
    private double price;
    private int number;
}

外层数据实体类

public class ShopCarShopItem {
    private boolean selected;
    private String shopName;
    private List<ShopCarGoodItem> shopCarGoods;
}

Adaptor的构造示例

先前我们提到过，把Holder作为Adaptor的内部类，还要为将数据绑定进去，再加上需要重写的三个方法，需要编写三块代码。

内层Adaptor代码

 public class ShopCarGoodAdapter extends RecyclerView.Adapter<ShopCarGoodAdapter.ShopCarGoodViewHolder>{
        private List<ShopCarGoodItem> shopCarGoodItems;

        public ShopCarGoodAdapter(List<ShopCarGoodItem> shopCarGoodItems) {
            this.shopCarGoodItems = shopCarGoodItems;
        }

        @NonNull
        @Override
        public ShopCarGoodViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            View view=LayoutInflater.from(getContext())
                    .inflate(R.layout.item_shopcar_goods,parent,false);
            return new ShopCarGoodViewHolder(view);
        }

        @Override
        public void onBindViewHolder(@NonNull ShopCarGoodViewHolder holder, int position) {
            holder.checkBox.setSelected(shopCarGoodItems.get(position).isSelected());
            Glide.with(getContext())
                    .load(shopCarGoodItems.get(position).getImgUrl())
                    .into(holder.imageView);
            holder.title.setText(shopCarGoodItems.get(position).getTitle());
            holder.ShippingForm.setText("发货方式："+shopCarGoodItems.get(position).getShippingForm());
            holder.price.setText(String.format("￥ %.2f",shopCarGoodItems.get(position).getPrice()));
            holder.number.setText(""+shopCarGoodItems.get(position).getNumber());
        }

        @Override
        public int getItemCount() {
            return shopCarGoodItems.size();
        }

        public class ShopCarGoodViewHolder extends RecyclerView.ViewHolder{
            CheckBox checkBox;
            ImageView imageView;
            TextView title;
            TextView ShippingForm;
            TextView price;
            TextView number;
            public ShopCarGoodViewHolder(@NonNull View itemView) {
                super(itemView);
                checkBox=itemView.findViewById(R.id.ShopCarGoodCheckBox);
                imageView=itemView.findViewById(R.id.ShopCarGoodImg);
                title=itemView.findViewById(R.id.ShopCarGoodTitle);
                ShippingForm=itemView.findViewById(R.id.ShopCarGoodShippingForm);
                price=itemView.findViewById(R.id.ShopCarGoodPrice);
                number=itemView.findViewById(R.id.ShopCarGoodNumbers);
            }
        }
    }

外层Adaptor代码

public class ShopCarAdapter extends RecyclerView.Adapter<ShopCarAdapter.ShopCarViewHolder>{
        private List<ShopCarShopItem> shopItems;

        public ShopCarAdapter(List<ShopCarShopItem> shopItems) {
            this.shopItems = shopItems;
        }

        @NonNull
        @Override
        public ShopCarViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            View view =LayoutInflater.from(getContext())
                    .inflate(R.layout.item_shopcar_shops,parent,false);
            return new ShopCarViewHolder(view);
        }

        @Override
        public void onBindViewHolder(@NonNull ShopCarViewHolder holder, int position) {
            holder.checkBox.setSelected(shopItems.get(position).isSelected());
            holder.textView.setText(shopItems.get(position).getShopName());
            ShopCarGoodAdapter shopCarGoodAdapter = new ShopCarGoodAdapter(shopItems.get(position).getShopCarGoods());
            holder.recyclerView.setAdapter(shopCarGoodAdapter);
            holder.recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
        }

        @Override
        public int getItemCount() {
            return shopItems.size();
        }

        public class ShopCarViewHolder extends RecyclerView.ViewHolder{
            CheckBox checkBox;
            TextView textView;
            RecyclerView recyclerView;
            public ShopCarViewHolder(@NonNull View itemView) {
                super(itemView);
                checkBox=itemView.findViewById(R.id.shopCheckBox);
                textView=itemView.findViewById(R.id.shopname);
                recyclerView=itemView.findViewById(R.id.shopGoodRecyclerView);

            }
        }
    }

四、运行结果

应用外层RecyclerView

RecyclerView recyclerView = view.findViewById(R.id.shopsView);
ShopCarAdapter shopCarAdapter = new ShopCarAdapter(shopItems);
recyclerView.setAdapter(shopCarAdapter);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));

目录CONTENT

安卓中RecyclerView的嵌套问题