取地址栏信息

URL地址：http://www.duankoo.com/test?someparam=abc

request.getpathinfo()//返回someparam=abc
request.getrequesturl()//返回 http://www.duankoo.com/test   
request.getrequesturi()//返回/test
request.getservletpath()//返回/abc  
request.getquerystring()//返回someparam=abc