Android中封装RecyclerView实现添加头部和底部示例代码

前言

我们大家都知道listview具有添加头部和添加底部的方法，但是recyclerview并没有这样子的方法。所以recyclerview是不能添加底部和头部的，但是能不能仿造listview来实现recyclerview添加头部和底部呢？答案当然是可行的。本文就来给大家介绍了关于android封装recyclerview添加头部和底部的相关内容，分享出来供大家参考学习，下面话不多说了，来一起看看详细的介绍吧。

首先看下实现的效果：

代码如下：

public class wrapmyrecyclerview extends recyclerview {

 private adapter madapter;
 private arraylist<view> mheaderviewinfos = new arraylist<>();//保存headerview
 private arraylist<view> mfooterviewinfos = new arraylist<>();//保存footerview

 public wrapmyrecyclerview(context context) {
  super(context);
 }

 public wrapmyrecyclerview(context context, @nullable attributeset attrs) {
  super(context, attrs);
 }

 public wrapmyrecyclerview(context context, @nullable attributeset attrs, int defstyle) {
  super(context, attrs, defstyle);
 }

 /**
  * 添加headerview
  * @param v
  */
 public void addheaderview(view v) {
  mheaderviewinfos.add(v);
  // wrap the adapter if it wasn't already wrapped.
  if (madapter != null) {
   if (!(madapter instanceof recyclerheaderviewlistadapter)) {
    wrapheaderlistadapterinternal();
   }
  }
 }

 /**
  * 添加一个footerview
  * @param v
  */
 public void addfooterview(view v) {
  mfooterviewinfos.add(v);
  // wrap the adapter if it wasn't already wrapped.
  if (madapter != null) {
   if (!(madapter instanceof recyclerheaderviewlistadapter)) {
    wrapheaderlistadapterinternal();
   }
  }
 }

 /**
  * 设置一个adapter
  * @param adapter
  */
 @override
 public void setadapter(adapter adapter) {

  if (mheaderviewinfos.size() > 0 || mfooterviewinfos.size() > 0) {
   madapter = wrapheaderlistadapterinternal(mheaderviewinfos, mfooterviewinfos, adapter);
  } else {
   madapter = adapter;
  }
  super.setadapter(madapter);
 }

 private void wrapheaderlistadapterinternal() {
  madapter = wrapheaderlistadapterinternal(mheaderviewinfos, mfooterviewinfos, madapter);
 }

 /**
  * 新建一个recyclerheaderviewlistadapter对象
  * 最终的adapter实现它
  * @param headerviewinfos
  * @param footerviewinfos
  * @param adapter
  * @return
  */
 protected recyclerheaderviewlistadapter wrapheaderlistadapterinternal(
   arraylist<view> headerviewinfos,
   arraylist<view> footerviewinfos,
   adapter adapter) {
  return new recyclerheaderviewlistadapter(headerviewinfos, footerviewinfos, adapter);
 }

}

这就是封装的recyclerview，里面主要有三个方法addheaderview、 addfooterview和重写的setadapter。这里的唯一的思想就是偷梁换柱，当我们添加头部、尾部或者设置adapter时，真正的adapter并不是我们传入的adapter，而是重新new 了一个recyclerheaderviewlistadapter。这才是recyclerview最终设置的adapter。

其实我们看到listview也是通过这样子的思想来添加头部和尾部的。

这就是listview的addheaderview方法，它会偷偷的创建headerviewlistadapter这个adapter。最终添加的header和footer在headerviewlistadapter里面实现。

public class recyclerheaderviewlistadapter extends recyclerview.adapter {

 private final arraylist<view> mheaderviewinfos;//保存headerview数据
 private final arraylist<view> mfooterviewinfos;//保存footerview数据
 private recyclerview.adapter madapter;   //用户自己构造的adapter
 private static final int recycler_header_view = 0x001;//headerview类型
 private static final int recycler_footer_view = 0x002;//footerview类型


 /**
  * 构造方法
  * 初始化
  * @param headerviewinfos
  * @param footerviewinfos
  * @param adapter
  */
 public recyclerheaderviewlistadapter(arraylist<view> headerviewinfos,
           arraylist<view> footerviewinfos,
           recyclerview.adapter adapter) {

  madapter = adapter;
  if (headerviewinfos == null) {
   mheaderviewinfos = new arraylist<>();
  } else {
   mheaderviewinfos = headerviewinfos;
  }

  if (footerviewinfos == null) {
   mfooterviewinfos = new arraylist<>();
  } else {
   mfooterviewinfos = footerviewinfos;
  }
 }

 /**
  * 根据getitemviewtype返回的条目类型
  * 创建不同的itemview
  * 传入的adapter，回调它的oncreateviewholder即可
  * @param parent
  * @param viewtype
  * @return
  */
 @override
 public recyclerview.viewholder oncreateviewholder(viewgroup parent, int viewtype) {
  if (viewtype == recycler_header_view){
   return new headerviewlayout(mheaderviewinfos.get(0));
  }else if (viewtype == recycler_footer_view){
   return new headerviewlayout(mfooterviewinfos.get(0));
  }
  return madapter.oncreateviewholder(parent,viewtype);
 }

 /**
  * 绑定数据
  * headerview和footerview不需要绑定数据，直接return即可
  * 传入的adapter需要回调它的onbindviewholder即可
  * @param holder
  * @param position
  */
 @override
 public void onbindviewholder(recyclerview.viewholder holder, int position) {
  //header
  int numheaders = getheaderscount();
  if (position < numheaders) {
   return ;
  }
  //adapter body
  final int adjposition = position - numheaders;
  int adaptercount = 0;
  if (madapter != null) {
   adaptercount = madapter.getitemcount();
   if (adjposition < adaptercount) {
    madapter.onbindviewholder(holder, adjposition);
    return ;
   }
  }
  //footer
 }

 /**
  * 返回条目的类型
  * 传入的adapter，回调它的getitemviewtype即可
  * @param position
  * @return
  */
 @override
 public int getitemviewtype(int position) {
  // header
  int numheaders = getheaderscount();
  if (position < numheaders) {
   return recycler_header_view;
  }
  // adapter
  final int adjposition = position - numheaders;
  int adaptercount = 0;
  if (madapter != null) {
   adaptercount = madapter.getitemcount();
   if (adjposition < adaptercount) {
    return madapter.getitemviewtype(position);
   }
  }
  // footer (off-limits positions will throw an indexoutofboundsexception)
  return recycler_footer_view;
 }

 /**
  * 总条目即：footerview的条目+headerview的条目+穿入的adapter条目
  * @return
  */
 @override
 public int getitemcount() {
  if (madapter != null) {
   return getfooterscount() + getheaderscount() + madapter.getitemcount();
  } else {
   return getfooterscount() + getheaderscount();
  }
 }

 /**
  * 获取headerview的条目
  * @return
  */
 public int getheaderscount() {
  return mheaderviewinfos.size();
 }

 /**
  * 获取footervie的条目
  * @return
  */
 public int getfooterscount() {
  return mfooterviewinfos.size();
 }

 /**
  * 这是footerview和headerview的viewholder需要
  * 这里只是提供一个构造器即可，实际上用处不大
  */
 private static class headerviewlayout extends recyclerview.viewholder{

  public headerviewlayout(view itemview) {
   super(itemview);
  }
 }

}

这是实现添加header、footer和传入adapter的recyclerheaderviewlistadapter。具体的逻辑都在文件的注释里面有说明。逻辑是仿造listview的headerviewlistadapter来实现的。

其实就是创建一个adapter，然后根据不同的条目类型来创建条目和绑定条目的数据即可。

<?xml version="1.0" encoding="utf-8"?>
<linearlayout
 xmlns: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:orientation="vertical"
 tools:context="com.wrap.recycler.wraprecyclerviewactivity">

 <com.lwj.wrap.recycler.wrapmyrecyclerview
  android:id="@+id/wrap_recyclerview"
  android:layout_width="match_parent"
  android:layout_height="match_parent"/>

</linearlayout>

这是布局文件

public class wraprecyclerviewactivity extends appcompatactivity {
 private wrapmyrecyclerview mrecyclerview;
 private myadapter mmyadapter;
 private list<string> mlist01 = new arraylist<>();
 private static final int wc = viewgroup.layoutparams.wrap_content;
 @override
 protected void oncreate(bundle savedinstancestate) {
  super.oncreate(savedinstancestate);
  setcontentview(r.layout.activity_wrap_recycler_view);
  getdata();
  mrecyclerview = (wrapmyrecyclerview) this.findviewbyid(r.id.wrap_recyclerview);
  mrecyclerview.setlayoutmanager(new linearlayoutmanager(this));

  //加入headerview
  viewgroup.layoutparams params = new viewgroup.layoutparams(wc,wc);
  imageview headerview = new imageview(this);
  headerview.setimageresource(r.drawable.timg);
  headerview.setlayoutparams(params);
  mrecyclerview.addheaderview(headerview);
  //设置adapter
  mmyadapter = new myadapter(this,mlist01);
  mrecyclerview.setadapter(mmyadapter);
  //加入footerview
  params = new viewgroup.layoutparams(wc,wc);
  imageview footerview = new imageview(this);
  footerview.setimageresource(r.drawable.hhfj);
  footerview.setlayoutparams(params);
  mrecyclerview.addfooterview(footerview);
  mmyadapter.notifydatasetchanged();

 }
 public void getdata() {
  for (int i = 0; i < 3; i++) {
   string data ="adapter...." + i;
   mlist01.add(data);
  }
 }
}

使用直接调用addheaderview、addfooterview即可。

除了这种方式来实现addheaderview和addfooterview，另外一种方式就是封装adapter来实现，原理还是保持不变：根据不同的条目类型来创建条目和绑定条目的数据。

public class mycirclerecycviewadapter extends recyclerview.adapter {
 public list<circleinfo.circlepageinfo> infos = null;
 private context mcontext;
 private listviewimgloader mloader;
 private view view_footer;//尾部
 private view view_header;//头部
 //type
 private int type_normal = 1000;
 private int type_header = 1001;
 private int type_footer = 1002;
 private int tagtype = type_normal;

 public mycirclerecycviewadapter(context context,list<circleinfo.circlepageinfo> datas) {
  this.infos = datas;
  this.mcontext = context;
  mloader = new listviewimgloader();
  mloader.setmemorycachesize(1024 * 1024);
  mloader.setvisibleitemcount(12);
 }

 @override
 public recyclerview.viewholder oncreateviewholder(viewgroup parent, int viewtype) {
  if (viewtype == type_footer) {
   tagtype = type_footer;
   return new mycircleitemholder(view_footer);
  } else if (viewtype == type_header) {
   tagtype = type_header;
   return new mycircleitemholder(view_header);
  } else {
   tagtype = type_normal;
   view view = layoutinflater.from(mcontext).inflate(r.layout.circle_gridview_items, parent,false);
   return new mycircleitemholder(view);
  }
 }

 @override
 public void onbindviewholder(recyclerview.viewholder holder, int position) {
  if (!isheaderview(position) && !isfooterview(position)) {
   if (haveheaderview()) position--;
   mycircleitemholder viewholder = (mycircleitemholder)holder;
   circleinfo.circlepageinfo minfo = infos.get(position);
   setdata(viewholder,minfo);
  }
 }

 @override
 public int getitemcount() {
  int count = (infos == null ? 0 : infos.size());
  if (view_footer != null) {
   count++;
  }
  if (view_header != null) {
   count++;
  }
  return count;
 }

 @override
 public int getitemviewtype(int position)
 {
  if (isheaderview(position)) {
   return type_header;
  } else if (isfooterview(position)) {
   return type_footer;
  } else {
   return type_normal;
  }
 }
 public void addheaderview(view headerview) {
  if (haveheaderview()) {
   throw new illegalstateexception("hearview has already exists!");
  } else {
   //避免出现宽度自适应
   viewgroup.layoutparams params = new viewgroup.layoutparams(utils.getrealpixel(30), utils.getrealpixel(230));
   headerview.setlayoutparams(params);
   view_header = headerview;
   notifyiteminserted(0);
  }
 }
 public void addfooterview(view footerview) {
  if (havefooterview()) {
   throw new illegalstateexception("footerview has already exists!");
  } else {
   viewgroup.layoutparams params = new viewgroup.layoutparams(viewgroup.layoutparams.match_parent, viewgroup.layoutparams.wrap_content);
   footerview.setlayoutparams(params);
   view_footer = footerview;
//   ifgridlayoutmanager();
   notifyiteminserted(getitemcount() - 1);
  }
 }

 private boolean haveheaderview() {
  return view_header != null;
 }

 public boolean havefooterview() {
  return view_footer != null;
 }

 private boolean isheaderview(int position) {
  return haveheaderview() && position == 0;
 }

 private boolean isfooterview(int position) {
  return havefooterview() && position == getitemcount() - 1;
 }


 private void setdata(final mycircleitemholder viewholder, final circleinfo.circlepageinfo minfo) {
  if(minfo == null || minfo == viewholder.taginfo)
  {
   return;
  }else{
   viewholder.taginfo = minfo;
   if(!strutils.isenpty(minfo.thread_unread)){
    if(minfo.thread_unread.equals("0")){
     viewholder.threaduunreadtv.setvisibility(view.invisible);
    }else{
     viewholder.threaduunreadtv.setvisibility(view.visible);
     viewholder.threaduunreadtv.settext(minfo.thread_unread);
    }
   }else{
    viewholder.threaduunreadtv.setvisibility(view.invisible);
   }

   if (!textutils.isempty(viewholder.tagurl)){
    if(minfo.circle_img_path != null && !(minfo.circle_img_path.equals(viewholder.tagurl))){
     setimage(viewholder.mimageview,minfo.circle_img_path);
    }
   }else{
    setimage(viewholder.mimageview,minfo.circle_img_path);
   }
   if (!textutils.isempty(minfo.circle_img_path)){
    viewholder.tagurl = minfo.circle_img_path;
   }
   if(minfo.circlename != null){
    if(minfo.circlename.length() > 5){
     string s = minfo.circlename.substring(0,5) + "...";
     viewholder.textview.settext(s);
    }else{
     viewholder.textview.settext(minfo.circlename);
    }
   }

  }
 }

 private void setimage(final colorfilterimageview mimageview, final string imgurl){
  mimageview.setbackgroundcolor(0xffadadad);
  mimageview.setimagebitmap(null);
  if(!textutils.isempty(imgurl))
  {
   mloader.loadimage(mimageview.hashcode(), imgurl, 300, new dnimg.ondnimglistener()
   {

    @override
    public void onprogress(string url, int downloadedsize, int totalsize)
    {
     // todo auto-generated method stub

    }

    @override
    public void onfinish(string url, string file, bitmap bmp)
    {
     if(url.equals(imgurl))
     {
      mimageview.setimagebitmap(bmp);
     }
    }
   });
  }else{
   mimageview.setbackgroundcolor(0xffadadad);
   mimageview.setimagebitmap(null);
  }
 }


 class mycircleitemholder extends recyclerview.viewholder{
  private colorfilterimageview mimageview;
  private textview textview;
  private circleinfo.circlepageinfo taginfo;
  private string tagurl;
  private textview threaduunreadtv;

  public mycircleitemholder(final view itemview) {
   super(itemview);
   if(tagtype == type_normal){
    mimageview = (colorfilterimageview)itemview.findviewbyid(r.id.quan_icon);
    mimageview.setscaletype(imageview.scaletype.center_crop);
    textview = (textview)itemview.findviewbyid(r.id.quan_name);
    threaduunreadtv = (textview)itemview.findviewbyid(r.id.quan_num);
    mimageview.setonclicklistener(new view.onclicklistener() {
     @override
     public void onclick(view v) {
      if (mlistener != null){
       mlistener.oncliitem(itemview,taginfo,threaduunreadtv);
      }
     }
    });
   }

  }
 }
 public onclickmycircleitemlistener mlistener;
 public void setonclickmycircleitemlistener(onclickmycircleitemlistener l){
  this.mlistener = l;
 }
 public interface onclickmycircleitemlistener{
  void oncliitem(view view,circleinfo.circlepageinfo info,view threadnumtv);
 }

 public void pauseloader(){
  if(mloader != null)
  {
   mloader.pause();
  }
 }
 public void resumeloader(){
  if(mloader != null)
  {
   mloader.resume();
  }
 }
 public void closeloader(){
  if(mloader != null)
  {
   mloader.close();
  }
 }

}

总结

以上就是这篇文章的全部内容了，希望本文的内容对各位android开发者们的学习或者工作能带来一定的帮助，如果有疑问大家可以留言交流，谢谢大家对的支持。