request.getRequestURL()和request.getRequestURI() 区别
request.getRequestURL()和request.getRequestURI() 区别
request.getRequestURI() 返回值类似：/myContext/requestdemo.jsp
返回值是String
request.getRequestURL() 返回值类似：http://localhost:8080/myContext/requestdemo.jsp
返回值是StringBuffer
