WEB項目，獲取路徑

1.獲取請求路徑
    request.getRequestURI()----->/wxgzh/test/login.html
    request.getRequestURL()----->http://192.168.11.200:8080/wxgzh/test/login.html
    request.getContextPath()----->/wxgzh
    request.getServletPath()----->/test/login.html
2.獲取本地路勁
    req.getSession().getServletContext().getRealPath("/");
     ------>D:\Eclipse\apache-tomcat-7.0.73\webapps\wxgzh\