使用RecyclerView添加Header和Footer的方法

recyclerview与listview原理是类似的：都是仅仅维护少量的view并且可以展示大量的数据集。recyclerview用以下两种方式简化了数据的展示和处理:

使用layoutmanager来确定每一个item的排列方式。

为增加和删除项目提供默认的动画效果。

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的使用之helloworld

recyclerview的使用之多item布局的加载

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 == mheadercount) {
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。

关于使用recyclerview添加header和footer的方法就给大家介绍到这里，希望对大家有所帮助！