Android中封装RecyclerView实现添加头部和底部示例代码
程序员文章站
2023-12-14 16:28:34
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...
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。