System.out.println("根目录所对应的绝对路径:" + request.getServletPath() + ""); 
String strPathFile = request.getSession().getServletContext().getRealPath(request.getRequestURI()); 
System.out.println("文件的绝对路径:" + strPathFile + ""); 
String strDirPath = new File(request.getSession().getServletContext().getRealPath(request.getRequestURI())).getParent(); 
System.out.println("目录的绝对路径:" + strDirPath + ""); 
    this.getServlet().getServletContext().getRealPath("/");//在struts的action中取得当前系统的根目录

　举例：http://localhost:7001/myservlet/somepath/test?someparam=somevalue
request.getPathInfo()：返回/somepath/test
request.getRequestURL()：返回http://localhost:7001/myservlet/somepath/test
request.getRequestURI()：返回/myservlet/somepath/test
request.getServletPath()：返回/myservlet
request.getQueryString()：返回someparam=somevalue
    request.getContextPath();  返回项目名/myservlet