* jsp 有9个内置对象
* javax.servlet.http.HttpServletRequest request
* final javax.servlet.http.HttpServletResponse response
* final javax.servlet.jsp.PageContext pageContext;
javax.servlet.http.HttpSession session = null;
final javax.servlet.ServletContext application;
final javax.servlet.ServletConfig config;
javax.servlet.jsp.JspWriter out = null;
final java.lang.Object page = this;
exception

jsp 有9个内置对象