Distinguish between different methods of obtaining the request through the request path
1, request.getRequestURL () returns the complete url, including Http protocol, port number, and the name of the servlet map path, but it does not include the requested parameter.
2, request.getRequestURI () is part of the value obtained in the request URL, the container and the web had not decode
3、request.getContextPath() 返回 the context of the request.
4, request.getServletPath () returns the part of the url calling servlet.
5, request.getQueryString () Returns the path of the query string behind url
Example: The current url: http: // localhost:? 8080 / CarsiLogCenter_new / idpstat.jsp action = idp.sptopn
request.getRequestURL() ：http://localhost:8080/CarsiLogCenter_new/idpstat.jsp
request.getRequestURI() ：/CarsiLogCenter_new/idpstat.jsp
request.getContextPath()：/CarsiLogCenter_new
request.getServletPath()： /idpstat.jsp
request.getQueryString()：action=idp.sptopn
1, request.getRequestURL () returns the complete url, including Http protocol, port number, and the name of the servlet map path, but it does not include the requested parameter.
2, request.getRequestURI () is part of the value obtained in the request URL, the container and the web had not decode
3、request.getContextPath() 返回 the context of the request.
4, request.getServletPath () returns the part of the url calling servlet.
5, request.getQueryString () Returns the path of the query string behind url
Example: The current url: http: // localhost:? 8080 / CarsiLogCenter_new / idpstat.jsp action = idp.sptopn
request.getRequestURL() ：http://localhost:8080/CarsiLogCenter_new/idpstat.jsp
request.getRequestURI() ：/CarsiLogCenter_new/idpstat.jsp
request.getContextPath()：/CarsiLogCenter_new
request.getServletPath()： /idpstat.jsp
request.getQueryString()：action=idp.sptopn