RecyclerView的使用（3）之添加Header和Footer

来源：互联网发布：飞行仪表显示软件开发编辑：程序博客网时间：2024/04/29 17:52

原创文章，转载请注明 http://blog.csdn.net/leejizhou/article/details/50742544 李济洲的博客

RecyclerView虽然作为ListView的替代者有着较好的性能提升，但是ListView的一些常用功能却没有提供，比如我们平时会经常用到的addHeaderView，addFooterView，既然RecyclerView没有提供这个方法，我们应该如何为列表添加头部和底部呢？通过看ListView的源码可以知道ListView的添加Header和Footer是靠Adapter里面动态添加的，所以我们按照这个思路也给RecyclerView添加HeaderView和FooterView，先看一下效果

如果你还不了解RecyclerView如何使用，可以看一下前几篇博文
RecyclerView的使用（1）之HelloWorld
RecyclerView的使用（2）之多Item布局的加载

这里写图片描述

RecyclerView实现添加HeaderView和FooterView的核心就是在Adapter里面的onCreateViewHolder根据viewType来判断是列表项还是HeaderView来分别加载不同的布局文件，当然viewType的判断规则也是由我们定义的，废话不多说，看一下具体的实现效果。

1：Gradle配置 build.gradle

 compile 'com.android.support:recyclerview-v7:23.1.1' compile 'com.android.support:cardview-v7:23.1.1'

2：主布局文件 activity_main.xml 很简单里面一个RecyclerView

<?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        xmlns:android="http://schemas.android.com/apk/res/android"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:id="@+id/rv_list"        /></LinearLayout>

3：列表项布局 rv_item.xml 外面一个CardView的卡片式容器里面一个TextView

<?xml version="1.0" encoding="utf-8"?><android.support.v7.widget.CardView    xmlns:card_view="http://schemas.android.com/apk/res-auto"    xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_margin="8dp"    android:id="@+id/cv_item"    android:foreground="?android:attr/selectableItemBackground"    card_view:cardCornerRadius="4dp"    card_view:cardElevation="4dp"    >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content">        <TextView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/tv_item_text"            android:text="test"            android:layout_margin="8dp"            />    </LinearLayout></android.support.v7.widget.CardView>

4：列表头部布局 rv_header.xml

<?xml version="1.0" encoding="utf-8"?><android.support.v7.widget.CardView    xmlns:card_view="http://schemas.android.com/apk/res-auto"    xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_margin="8dp"    android:id="@+id/cv_item"    android:foreground="?android:attr/selectableItemBackground"    card_view:cardCornerRadius="4dp"    card_view:cardElevation="4dp"    card_view:cardBackgroundColor="#4CAF50"    >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="150dp"        >        <TextView            android:layout_width="match_parent"            android:layout_height="match_parent"            android:text="Header"            android:textSize="30sp"            android:textColor="#ffffff"            android:gravity="center"            />    </LinearLayout></android.support.v7.widget.CardView>

5：列表底部布局 rv_footer.xml

<?xml version="1.0" encoding="utf-8"?><android.support.v7.widget.CardView    xmlns:card_view="http://schemas.android.com/apk/res-auto"    xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_margin="8dp"    android:id="@+id/cv_item"    android:foreground="?android:attr/selectableItemBackground"    card_view:cardCornerRadius="4dp"    card_view:cardElevation="4dp"    card_view:cardBackgroundColor="#E91E63"    >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="150dp"        >        <TextView            android:layout_width="match_parent"            android:layout_height="match_parent"            android:text="Footer"            android:textSize="30sp"            android:textColor="#ffffff"            android:gravity="center"            />    </LinearLayout></android.support.v7.widget.CardView>

6：*HeaderBottomAdapter.java，RecyclerView的Adapter，在getItemViewType方法里面判断了当前Item的类型，然后在onCreateViewHolder跟据item的类型分别加载不同的布局以实现HeaderView和FooterView，其他方法的含义可以参考注释

import android.content.Context;import android.support.v7.widget.RecyclerView;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;/** * Created by Lijizhou on 2016/2/24. * Blog:http://blog.csdn.net/leejizhou * QQ:3107777777 */public class HeaderBottomAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {    //item类型    public static final int ITEM_TYPE_HEADER = 0;    public static final int ITEM_TYPE_CONTENT = 1;    public static final int ITEM_TYPE_BOTTOM = 2;    //模拟数据    public String [] texts={"java","python","C++","Php",".NET","js","Ruby","Swift","OC"};    private LayoutInflater mLayoutInflater;    private Context mContext;    private int mHeaderCount=1;//头部View个数    private int mBottomCount=1;//底部View个数    public HeaderBottomAdapter(Context context) {        mContext = context;        mLayoutInflater = LayoutInflater.from(context);    }    //内容长度    public int getContentItemCount(){        return texts.length;    }    //判断当前item是否是HeadView    public boolean isHeaderView(int position) {        return mHeaderCount != 0 && position < mHeaderCount;    }    //判断当前item是否是FooterView    public boolean isBottomView(int position) {        return mBottomCount != 0 && position >= (mHeaderCount + getContentItemCount());    }    //判断当前item类型    @Override    public int getItemViewType(int position) {        int dataItemCount = getContentItemCount();        if (mHeaderCount != 0 && position < mHeaderCount) {            //头部View            return ITEM_TYPE_HEADER;        } else if (mBottomCount != 0 && position >= (mHeaderCount + dataItemCount)) {            //底部View            return ITEM_TYPE_BOTTOM;        } else {            //内容View            return ITEM_TYPE_CONTENT;        }    }    //内容 ViewHolder    public static class ContentViewHolder extends RecyclerView.ViewHolder {        private TextView textView;        public ContentViewHolder(View itemView) {            super(itemView);            textView=(TextView)itemView.findViewById(R.id.tv_item_text);        }    }    //头部 ViewHolder    public static class HeaderViewHolder extends RecyclerView.ViewHolder {        public HeaderViewHolder(View itemView) {            super(itemView);        }    }    //底部 ViewHolder    public static class BottomViewHolder extends RecyclerView.ViewHolder {        public BottomViewHolder(View itemView) {            super(itemView);        }    }    @Override    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        if (viewType ==ITEM_TYPE_HEADER) {            return new HeaderViewHolder(mLayoutInflater.inflate(R.layout.rv_header, parent, false));        } else if (viewType == ITEM_TYPE_CONTENT) {            return  new ContentViewHolder(mLayoutInflater.inflate(R.layout.rv_item, parent, false));        } else if (viewType == ITEM_TYPE_BOTTOM) {            return new BottomViewHolder(mLayoutInflater.inflate(R.layout.rv_footer, parent, false));        }        return null;    }    @Override    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {        if (holder instanceof HeaderViewHolder) {        } else if (holder instanceof ContentViewHolder) {            ((ContentViewHolder) holder).textView.setText(texts[position - mHeaderCount]);        } else if (holder instanceof BottomViewHolder) {        }    }    @Override    public int getItemCount() {       return mHeaderCount + getContentItemCount() + mBottomCount;    }}

7：最后一步，MainActivity.java

import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.support.v7.widget.GridLayoutManager;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;public class MainActivity extends AppCompatActivity {    private RecyclerView mRecyclerView;    private HeaderBottomAdapter adapter;    GridLayoutManager gridLayoutManager;    LinearLayoutManager layoutManager;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        mRecyclerView=(RecyclerView)findViewById(R.id.rv_list);        //List布局        layoutManager=new LinearLayoutManager(this);        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);        mRecyclerView.setLayoutManager(layoutManager);        mRecyclerView.setAdapter(adapter=new HeaderBottomAdapter(this));        //Grid布局 //        gridLayoutManager=new GridLayoutManager(MainActivity.this, 2);//        mRecyclerView.setLayoutManager(gridLayoutManager);//这里用线性宫格显示 类似于grid view//        mRecyclerView.setAdapter(adapter=new HeaderBottomAdapter(this));//////            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {//                @Override//                public int getSpanSize(int position) {//                    return (adapter.isHeaderView(position) || adapter.isBottomView(position)) ? gridLayoutManager.getSpanCount() : 1;//                }//            });    }}

这里注意一点，如果你的RecyclerView使用Grid类型列表在设置Adapter后需要调用这个方法，根据当前Item类型来判断占据的横向格数，这也是Adapter里面实现isHeaderView和isBottomView的缘故

 gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {                @Override                public int getSpanSize(int position) {                    return (adapter.isHeaderView(position) || adapter.isBottomView(position)) ? gridLayoutManager.getSpanCount() : 1;                }           });

Ok，RecyclerView添加Header和Footer就这样轻松实现了，你也可以把Adapter再次封装更有利于日常的开发，本篇博文的源码下载地址 下载地址

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