Android RecyclerView添加Header头部

Android RecyclerView不像以前的ListView那样直接添加头部，如果要给RecyclerView增加头部，则需要自己写或者使用第三方开源项目。
RecyclerViewHeader是github上的一个开源项目，旨在为Android RecyclerView增加头部，其在github上的项目主页是：https://github.com/blipinsk/RecyclerViewHeader
RecyclerViewHeader使用相对比较简单，写一个例子。
注意RecyclerViewHeader的布局文件写法：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <com.bartoszlipinski.recyclerviewheader2.RecyclerViewHeader xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/header"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="top">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@android:color/holo_orange_light"
            android:gravity="center"
            android:text="zhang phil @ csdn"
            android:textColor="@android:color/white" />

    </com.bartoszlipinski.recyclerviewheader2.RecyclerViewHeader>

</FrameLayout>

上层Java代码：

package zhangphil.app;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.bartoszlipinski.recyclerviewheader2.RecyclerViewHeader;

public class MainActivity extends AppCompatActivity {

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

        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        recyclerView.setLayoutManager(layoutManager);

        ItemAdapter adapter = new ItemAdapter();
        recyclerView.setAdapter(adapter);

        //添加RecyclerView头部
        RecyclerViewHeader header = (RecyclerViewHeader) findViewById(R.id.header);
        header.attachTo(recyclerView);
    }


    private class ItemViewHolder extends RecyclerView.ViewHolder {
        public TextView text;

        public ItemViewHolder(View itemView) {
            super(itemView);
            text = (TextView) itemView.findViewById(android.R.id.text1);
        }
    }

    private class ItemAdapter extends RecyclerView.Adapter<ItemViewHolder> {

        @Override
        public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = View.inflate(parent.getContext(), android.R.layout.simple_list_item_1, null);
            ItemViewHolder holder = new ItemViewHolder(view);
            return holder;
        }

        @Override
        public void onBindViewHolder(ItemViewHolder holder, int position) {
            holder.text.setText(String.valueOf(position));
        }

        @Override
        public int getItemCount() {
            return 20;
        }
    }
}

代码运行结果：