http://www.cnblogs.com/zhulin/archive/2011/04/06/2006865.html

http://www.ietf.org/rfc/rfc3986.txt

地址：http://www.w3.org/Addressing/rfc1808.txt

http://wiki.jabbercn.org/RFC3986#.E9.99.84.E5.BD.95A._.E4.B8.BAURI.E6.94.B6.E9.9B.86.E7.9A.84ABNF

RFC 1808          Relative Uniform Resource Locators          June 1995

格式：      :///;?#

each of which, except , may be absent from a particular URL.

These components are defined as follows (a complete BNF is provided

in Section 2.2):

scheme ":"  ::= scheme name, as per Section 2.1 of RFC 1738 [2].

"//" net_loc ::= network location and login information, as per

Section 3.1 of RFC 1738 [2].

"/" path    ::= URL path, as per Section 3.1 of RFC 1738 [2].

";" params  ::= object parameters (e.g., ";type=a" as in

Section 3.2.2 of RFC 1738 [2]).

"?" query    ::= query information, as per Section 3.3 of

RFC 1738 [2].

"#" fragment ::= fragment identifier.

The following are two example URIs and their component parts:

foo://example.com:8042/over/there?name=ferret#nose

\_/  \______________/\_________/ \_________/ \__/

 |                |                     |                 |          |

scheme    authority           path        query  fragment

|  _____________________|__

/ \ /                        \

urn:example:animal:ferret:nose