引入flask-bootstrap后,访问不了static目录下的任何资源是怎么回事?

网站根目录下有一static目录,里面放任何资源都访问不了
如static目录下有一css文件:public.css
通过网址:127.0.0.1:5000/static/public.css访问不了

打印网站的url_map,显示如下:
Map([<Rule ‘/static/’ (HEAD, OPTIONS, GET) → static>,
<Rule ‘/static/bootstrap/’ (HEAD, OPTIONS, GET) → bootstrap.static>,
<Rule ‘/’ (HEAD, OPTIONS, GET) → fduser.home>,
<Rule ‘/registerMenu’ (HEAD, OPTIONS, GET) → fduser.registerMenu>,
<Rule ‘/regstep1’ (HEAD, OPTIONS, GET) → fduser.step1>,
<Rule ‘/regstep2’ (HEAD, OPTIONS, GET) → fduser.step2>,
<Rule ‘/regstep3’ (HEAD, OPTIONS, GET) → fduser.step3>,
<Rule ‘/bgadmin’ (HEAD, OPTIONS, GET) → bgadmin.index>])