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 %>
