Jsp内置对象和EL隐藏（内置）对象

JSP中的内置对象一共有九个, 由于有的不太常用, 所以总是记不住, 从Sun公司的网站上找到的PDF文档, 把这一部分放在这里, 以备随时查用:

JSP九个内置对象:

Implicit Objects for Scriptlets (JSP Scriplets中的隐含对象)		Type (对应类型)	Scope (范围)	Some Useful Methods (see class or interface for others) (常用的方法)
1	request	Subclass of javax.servlet.ServletRequest	Request	getAttribute, getParameter, getParameterNames, getParameterValues, setAttribute
2	response	Subclass of javax.servlet.ServletResponse	Page	Not typically used by JSP page authors
3	pageContext	javax.servlet.jsp.PageContext	Page	findAttribute, getAttribute, getAttributesScope, getAttributeNamesInScope, setAttribute
4	session	javax.servlet.http.HttpSession	Session	getAttribute, getId, setAttribute
5	application	javax.servlet.ServletContext	Application	getAttribute, getMimeType, getRealPath, setAttribute
6	out	javax.servlet.jsp.JspWriter	Page	clear, clearBuffer, flush, getBufferSize, getRemaining
7	config	javax.servlet.ServletConfig	Page	getInitParameter, getInitParameterNames
8	page	java.lang.Object	Page	Not typically used by JSP page authors
9	exception	java.lang.Throwable	Page	getMessage, getLocalizedMessage, printStackTrace, toString

JSP十一个用于EL表达式的隐含(内置)对象:

Implicit Objects for EL Expressions 用于EL表达式的隐含对象	Type 类型	Description 具体说明
pageContext	javax.servlet.jsp.PageContext	The context for the JSP page. Provides access to various objects, including servletContext, session, request, and response.
pageScope	java.util.Map	Maps page-scoped variable names to their values.
requestScope	java.util.Map	Maps request-scoped variable names to their values.
sessionScope	java.util.Map	Maps session-scoped variable names to their values.
applicationScope	java.util.Map	Maps application-scoped variable names to their values.
param	java.util.Map	Maps a request parameter to a single String parameter value (obtained by calling ServletReqwuest.getParameter(String name)).
paramValues	java.util.Map	Maps a request parameter name to an array of String values for that parameter name (obtained by calling ServletRequest.getParameterValues(String name)).
header	java.util.Map	Maps a request header name to a single String header value (obtained by calling ServletRequest.getHeader(String name)).
headerValues	java.util.Map	Maps a request header name to an array of String values for that header (obtained by calling ServletRequest.getHeaders(String)).
coookie	java.util.Map	Maps a cookie name to a single Cookie object. Cookies are retrieved according to the semantics of HttpServletRequest.getCookies(). If the same name is shared by multiple cookies, an implementation must use the first one encountered in the array of Cookie objects returned by the getCookies() method. However, the ordering of cookies is currently unsspecified in the Servlet specification.
initParam	java.util.Map	Maps a context initialization parameter name to a String parameter value (obtained by calling ServletContext.getInitparameter(String name)).

EL表达式: ${requestScope.product.productId }

可换成Jsp: <%= request.getParamenter("product").productId %>