后台：
HttpServletRequest httpRequest=(HttpServletRequest)request;
String strBackUrl = "http://" + request.getServerName() //服务器地址
+ ":"
+ request.getServerPort() //端口号
+ httpRequest.getContextPath() //项目名称
+ httpRequest.getServletPath() //请求页面或其他地址
+ "?" + (httpRequest.getQueryString()); //参数
前台：
var url = window.location.href; //协议+ip+端口号
