flask获取本页面网址 request.url, request.url_root
eg. http://www.example.com/myapplication/page.html?x=y
In this case the values of the above mentioned attributes would be the following:
request.path /page.html
request.script_root /myapplication
request.base_url http://www.example.com/myapplication/page.html
request.url http://www.example.com/myapplication/page.html?x=y
request.url_root http://www.example.com/