JSP EL的内置对象 JSP的内置对象
pageContext-------->page
pageScope---------->pageContext
requestScope------->request
sessionScope------->session
applicationScope--->application
param-------------->request.getParameter()
paramValues-------->request.getParameterValues()
cookie------------->request.getCookie();
initParam---------->application.getInitParameter()
header------------->request.getHeader()
