开始逐渐领略到itemdecoration的美~
今天让我 使用 itemdecoration 来完成 可推动的悬浮导航栏的效果，最终实现的效果如下图：
具体实现步骤如下：
根据我前面的文章所讲的recyclerview的基本使用，我们先来完成基本的recyclerview：
第一步：布局里写一个recyclerview
第二步：实例化
recyclerview = (recyclerview) findviewbyid(r.id.recyclerview);
第三步：获取所需的数据 (这里我们来个真实点的情景，去联网请求数据)
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/**
* 联网请求所需的url
*/
public string url="http://api.meituan.com/mmdb/movie/v2/list/rt/order/coming.json?ci=1&limit=12&token=&__vhost=api.maoyan.com&utm_campaign=amoviebmoviecd-1&moviebundleversion=6801&utm_source=xiaomi&utm_medium=android&utm_term=6.8.0&utm_content=868030022327462&net=255&dmodel=mi%205&uuid=0894de03c76f6045d55977b6d4e32b7f3c6aab02f9cea042987b380ec5687c43&lat=40.100673&lng=116.378619&__skck=6a375bce8c66a0dc293860dfa83833ef&__skts=1463704714271&__skua=7e01cf8dd30a179800a7a93979b430b2&__skno=1a0b4a9b-44ec-42fc-b110-ead68bcc2824&__skcy=sxcdkbgi20cgxqppzvhcu3%2fkzde%3d";
//联网获取数据
getdatafromnet();
/**
* 使用okhttputils进行联网请求数据
*/
private void getdatafromnet() {
okhttputils.
get()
.url(url)
.build()
.execute(new stringcallback() {
@override
public void onerror(okhttp3.call call, exception e, int id) {
log.e("tag", "联网失败" + e.getmessage());
}
@override
public void onresponse(string response, int id) {
log.e("tag", "联网成功==" + response);
//联网成功后使用fastjson解析
processdata(response);
}
});
}
/**
* 使用fastjson进行解析
*
* @param json
*/
private void processdata(string json) {
//这里使用gsonformat生成对应的bean类
jsonobject jsonobject = parseobject(json);
string data = jsonobject.getstring("data");
jsonobject dataobj = json.parseobject(data);
string coming = dataobj.getstring("coming");
list<waitmvbean.databean.comingbean> comingslist = parsearray(coming, waitmvbean.databean.comingbean.class);
//测试是否解析数据成功
// string strtest = comingslist.get(0).getcat();
// log.e("tag", strtest + "222");
//解析数据成功,设置适配器-->
}
}
第四步：解析数据成功后，创建并设置适配器,并传递相关数据
//解析数据成功,设置适配器
myrecycleradapter adapter = new myrecycleradapter( mcontext,comingslist);
recyclerview.setadapter(adapter);
适配器：
public class myrecycleradapter extends recyclerview.adapter {
private final list<waitmvbean.databean.comingbean> comingslist;
private final context mcontext;
private final layoutinflater mlayoutinflater;
public myrecycleradapter(context mcontext, list<waitmvbean.databean.comingbean> comingslist) {
this.mcontext = mcontext;
this.comingslist = comingslist;
mlayoutinflater = layoutinflater.from(mcontext);
}
@override
public recyclerview.viewholder oncreateviewholder(viewgroup parent, int viewtype) {
return new myviewholder(mlayoutinflater.inflate(r.layout.date_item, null));
}
@override
public void onbindviewholder(recyclerview.viewholder holder, int position) {
myviewholder myholder = (myviewholder) holder;
myholder.setdata(position);
}
@override
public int getitemcount() {
return comingslist.size();
}
class myviewholder extends recyclerview.viewholder {
private textview mv_name;
private textview mv_dec;
private textview mv_date;
private imageview imageview;
public myviewholder(view itemview) {
super(itemview);
mv_name = (textview) itemview.findviewbyid(r.id.mv_name);
mv_dec = (textview) itemview.findviewbyid(r.id.mv_dec);
mv_date = (textview) itemview.findviewbyid(r.id.mv_date);
imageview = (imageview) itemview.findviewbyid(r.id.image);
}
public void setdata(int position) {
waitmvbean.databean.comingbean coming = comingslist.get(position);
string name = coming.getnm();
mv_name.settext(name);
string date = coming.getshowinfo();
mv_date.settext(date);
string dec = coming.getscm();
mv_dec.settext(dec);
//注：当你发下图片无法打开是，做个字符串替换即可
string imagurl = coming.getimg();
string newimagurl = imagurl.replaceall("w.h", "50.80");
//使用glide加载图片
glide.with(mcontext)
.load(newimagurl)
.into(imageview);
}
}
}
item的布局：
<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#ffffff"
android:gravity="center_vertical"
android:orientation="horizontal">
<imageview
android:id="@+id/image"
android:layout_width="70dp"
android:layout_height="110dp"
android:layout_marginbottom="5dp"
android:layout_marginleft="10dp"
android:layout_marginright="8dp"
android:layout_margintop="5dp" />
<linearlayout
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginleft="6dp"
android:layout_weight="1"
android:orientation="vertical">
<textview
android:id="@+id/mv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="神奇動物在哪裏"
android:textcolor="#000000"
android:textsize="15sp" />
<linearlayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<textview
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="观众"
android:textcolor="#55000000"
android:textsize="14sp" />
<textview
android:id="@+id/tv_people"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="9.0 "
android:textcolor="#ffce42"
android:textsize="18sp" />
<textview
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" | 专业"
android:textcolor="#55000000"
android:textsize="14sp" />
<textview
android:id="@+id/tv_professional"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="6.7"
android:textcolor="#ffce42"
android:textsize="18sp" />
</linearlayout>
<textview
android:id="@+id/mv_dec"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margintop="8dp"
android:text="神奇動物城，法師顯超能"
android:textcolor="#99000000"
android:textsize="11sp" />
<textview
android:id="@+id/mv_date"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margintop="10dp"
android:text="今天165家影院放映2088场"
android:textcolor="#99000000"
android:textsize="11sp" />
</linearlayout>
</linearlayout>
第五步：一定不能忘！！！
recycleview不仅要设置适配器还要设置布局管理者,否则图片不显示
gridlayoutmanager manager = new gridlayoutmanager(this, 1);
recyclerview.setlayoutmanager(manager);
此时recyclerview简单的完成效果如下：
下面开始做 可推动的 悬浮导航栏：
第一步：首先我们来写一个类，它起标记的作用，来放每一个item的对应的悬浮栏的字符串
public class namebean {
string name;
public string getname() {
return name;
}
public void setname(string name) {
this.name = name;
}
}
第二步：自定义一个sectiondecoration 类 继承 recyclerview的itemdecoration
public class sectiondecoration extends recyclerview.itemdecoration {
private static final string tag = "sectiondecoration";
private list<namebean> datalist;
private decorationcallback callback;
private textpaint textpaint;
private paint paint;
private int topgap;
private int alignbottom;
private paint.fontmetrics fontmetrics;
public sectiondecoration(list<namebean> datalist, context context, decorationcallback decorationcallback) {
resources res = context.getresources();
this.datalist = datalist;
this.callback = decorationcallback;
//设置悬浮栏的画笔---paint
paint = new paint();
paint.setcolor(res.getcolor(r.color.colorgray));
//设置悬浮栏中文本的画笔
textpaint = new textpaint();
textpaint.setantialias(true);
textpaint.settextsize(densityutil.dip2px(context, 14));
textpaint.setcolor(color.dkgray);
textpaint.settextalign(paint.align.left);
fontmetrics = new paint.fontmetrics();
//决定悬浮栏的高度等
topgap = res.getdimensionpixelsize(r.dimen.sectioned_top);
//决定文本的显示位置等
alignbottom = res.getdimensionpixelsize(r.dimen.sectioned_alignbottom);
}
@override
public void getitemoffsets(rect outrect, view view, recyclerview parent, recyclerview.state state) {
super.getitemoffsets(outrect, view, parent, state);
int pos = parent.getchildadapterposition(view);
log.i(tag, "getitemoffsets：" + pos);
string groupid = callback.getgroupid(pos);
if (groupid.equals("-1")) return;
//只有是同一组的第一个才显示悬浮栏
if (pos == 0 || isfirstingroup(pos)) {
outrect.top = topgap;
if (datalist.get(pos).getname() == "") {
outrect.top = 0;
}
} else {
outrect.top = 0;
}
}
@override
public void ondraw(canvas c, recyclerview parent, recyclerview.state state) {
super.ondraw(c, parent, state);
int left = parent.getpaddingleft();
int right = parent.getwidth() - parent.getpaddingright();
int childcount = parent.getchildcount();
for (int i = 0; i < childcount; i++) {
view view = parent.getchildat(i);
int position = parent.getchildadapterposition(view);
string groupid = callback.getgroupid(position);
if (groupid.equals("-1")) return;
string textline = callback.getgroupfirstline(position).touppercase();
if (textline == "") {
float top = view.gettop();
float bottom = view.gettop();
c.drawrect(left, top, right, bottom, paint);
return;
} else {
if (position == 0 || isfirstingroup(position)) {
float top = view.gettop() - topgap;
float bottom = view.gettop();
//绘制悬浮栏
c.drawrect(left, top - topgap, right, bottom, paint);
//绘制文本
c.drawtext(textline, left, bottom, textpaint);
}
}
}
}
@override
public void ondrawover(canvas c, recyclerview parent, recyclerview.state state) {
super.ondrawover(c, parent, state);
int itemcount = state.getitemcount();
int childcount = parent.getchildcount();
int left = parent.getpaddingleft();
int right = parent.getwidth() - parent.getpaddingright();
float lineheight = textpaint.gettextsize() + fontmetrics.descent;
string pregroupid = "";
string groupid = "-1";
for (int i = 0; i < childcount; i++) {
view view = parent.getchildat(i);
int position = parent.getchildadapterposition(view);
pregroupid = groupid;
groupid = callback.getgroupid(position);
if (groupid.equals("-1") || groupid.equals(pregroupid)) continue;
string textline = callback.getgroupfirstline(position).touppercase();
if (textutils.isempty(textline)) continue;
int viewbottom = view.getbottom();
float texty = math.max(topgap, view.gettop());
//下一个和当前不一样移动当前
if (position + 1 < itemcount) {
string nextgroupid = callback.getgroupid(position + 1);
//组内最后一个view进入了header
if (nextgroupid != groupid && viewbottom < texty) {
texty = viewbottom;
}
}
//texty - topgap决定了悬浮栏绘制的高度和位置
c.drawrect(left, texty - topgap, right, texty, paint);
//left+2*alignbottom 决定了文本往左偏移的多少（加-->向左移）
//texty-alignbottom 决定了文本往右偏移的多少 (减-->向上移)
c.drawtext(textline, left + 2 * alignbottom, texty - alignbottom, textpaint);
}
}
/**
* 判断是不是组中的第一个位置
*
* @param pos
* @return
*/
private boolean isfirstingroup(int pos) {
if (pos == 0) {
return true;
} else {
// 因为是根据 字符串内容的相同与否 来判断是不是同意组的，所以此处的标记id 要是string类型
// 如果你只是做联系人列表，悬浮框里显示的只是一个字母，则标记id直接用 int 类型就行了
string prevgroupid = callback.getgroupid(pos - 1);
string groupid = callback.getgroupid(pos);
//判断前一个字符串 与 当前字符串 是否相同
if (prevgroupid.equals(groupid)) {
return false;
} else {
return true;
}
}
}
//定义一个借口方便外界的调用
interface decorationcallback {
string getgroupid(int position);
string getgroupfirstline(int position);
}
}
第三步：在向list集合中先把每一个item的 起“标记”作用的字符串都加进去
setpullaction(comingslist);
private void setpullaction(list<waitmvbean.databean.comingbean> comingslist) {
datalist = new arraylist<>();
for (int i = 0; i < comingslist.size(); i++) {
namebean namebean = new namebean();
string name0 = comingslist.get(i).getcomingtitle();
namebean.setname(name0);
datalist.add(namebean);
}
}
第四步：在setadapter() 前，为recyclerview添加itemdecoration:
recyclerview.additemdecoration(new sectiondecoration(datalist,mcontext, new sectiondecoration.decorationcallback() {
//返回标记id (即每一项对应的标志性的字符串)
@override
public string getgroupid(int position) {
if(datalist.get(position).getname()!=null) {
return datalist.get(position).getname();
}
return "-1";
}
//获取同组中的第一个内容
@override
public string getgroupfirstline(int position) {
if(datalist.get(position).getname()!=null) {
return datalist.get(position).getname();
}
return "";
}
}));
这样就完成了~
再看一眼最终效果感受一下：
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