前置条件：
http://127.0.0.1:9001/aiforce/authentication/sso
1）request.getContextPath()
/aiforce
2）request.getServletPath()
/authentication/sso
只返回传递到servlet的路径
3）request.getPathInfo()
/authentication/sso
只返回传递到servlet的路径
4）request.getRequestURI
/aiforce/authentication/sso
5）request.getRequestURL
http://localhost:9001/aiforce/authentication/sso
返回完整路径
