Android：RecyclerView 添加 Header 和 Footer（二）

一、简介

ConcatAdapter 是谷歌新推出的adapter,用它可连接多个adapter,实现一个列表多种item样式，这里不再使用传统的方法实现，而是借助于 ConcatAdapter 来添加 Header和footer。

二、实现

1.布局

列表

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:paddingBottom="@dimen/activity_vertical_margin"
 android:paddingLeft="@dimen/activity_horizontal_margin"
 android:paddingRight="@dimen/activity_horizontal_margin"
 android:paddingTop="@dimen/activity_vertical_margin"
 tools:context="com.study.wnw.recyclerviewheaderfooter.MainActivity">
 
 <androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>
    
</RelativeLayout>

列表项(item)

<?xml version="1.0" encoding="utf-8"?><LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="match_parent"
 android:layout_height="50dp">
 <TextView
    android:id="@+id/item"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:textSize="20sp"
    android:textColor="@color/colorAccent"
    android:gravity="center"
    android:background="#08e630"/>
</LinearLayout>

Header

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="match_parent"
 android:layout_height="100dp">
 
 <TextView
    android:id="@+id/header"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="我是Header"
    android:textSize="30sp"
    android:textColor="#fde70b0b"
    android:background="#f9777979"
    android:gravity="center"/>
</LinearLayout>

Footer

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="match_parent"
 android:layout_height="100dp">
 
 <TextView
    android:id="@+id/footer"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="我是Footer"
    android:textSize="30sp"
    android:textColor="#fde70b0b"
    android:background="#f9777979"
    android:gravity="center"/>
</LinearLayout>

2.代码实现

MainActivity.java

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_header_demo1);

        RecyclerView recyclerView = findViewById(R.id.recyclerview);

        HeaderAdapter headerAdapter = new HeaderAdapter();

        List<String> list = new ArrayList<>();
        list.add("张三");
        list.add("李四");
        list.add("王五");
        list.add("赵六");
        DataListAdapter dataListAdapter = new DataListAdapter(this, list);

        FooterAdapter footerAdapter = new FooterAdapter();
        ConcatAdapter concatAdapter = new ConcatAdapter(headerAdapter,dataListAdapter,footerAdapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(concatAdapter);
    }
}

HeaderAdapter.java

public class HeaderAdapter extends RecyclerView.Adapter<HeaderAdapter.HeaderViewHolder>{

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

    @Override
    public void onBindViewHolder(@NonNull HeaderViewHolder holder, int position) {
        holder.header.setText("我是Header");
    }

    @Override
    public int getItemCount() {
        return 1;
    }

    class HeaderViewHolder extends RecyclerView.ViewHolder{

        TextView header;
        public HeaderViewHolder(@NonNull View itemView) {
            super(itemView);
            header = itemView.findViewById(R.id.header);
        }
    }
}

FooterAdapter.java

public class FooterAdapter extends RecyclerView.Adapter<FooterAdapter.FooterViewHolder>{

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

    @Override
    public void onBindViewHolder(@NonNull FooterViewHolder holder, int position) {
        holder.footer.setText("我是Footer");
    }

    @Override
    public int getItemCount() {
        return 1;
    }

    class FooterViewHolder extends RecyclerView.ViewHolder{

        TextView footer;
        public FooterViewHolder(@NonNull View itemView) {
            super(itemView);
            footer = itemView.findViewById(R.id.header);
        }
    }
}

DataListAdapter.java

public class DataListAdapter extends RecyclerView.Adapter<DataListAdapter.DataViewHolder> {
    private Context mContext;
    private List<String> mDataList;

    public DataListAdapter(Context context,List<String> dataList){
        mContext = context;
        mDataList = dataList;
    }

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

    @Override
    public void onBindViewHolder(@NonNull DataViewHolder holder, int position) {
        holder.textView.setText("item:" + position + mDataList.get(position));
    }

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

    class DataViewHolder extends RecyclerView.ViewHolder {
        TextView textView;

        public DataViewHolder(@NonNull View itemView) {
            super(itemView);
            textView = itemView.findViewById(R.id.item);
        }
    }
}