Eight expression language ----------------------------------------- ----- -------------------------------------------------- ---------
expression language is JSP2.0 the new features, the use of the expression language can easily access flag (providing a total page (pageContext) in the jsp, request, session and application four flag species)
expression using language attribute name} {$ If the output is automatically null empty string "" indicates
----------------------- ----------------- --------------------------- built-in object expression language ---------------------------
provides a number of built-in expression language objects:
pageContext represent pageContext object
pageScope means the search range output from the page properties
requestScope a lookup request output attribute from the attribute range
sessionScope a lookup output attribute from the session attribute range
applicationScope lookup output attribute indicates attribute range from application
param accepts parameters passed to this page
paramValues receiving a set of parameters passed to this page
receiving a data header information header
headerValues receiving a data group header
cookie in the cookie data extracted
initParam initialization parameters acquired configuration
$ {name} attribute properties can be obtained from various attributes stored range, the default order is page-> request- > session-> application
if you want to find the range specified properties can be $ {requestScope format attribute name}
call built-in objects: use pageContext available request, session, application examples
pageContext.session format accomplished by reflection
<% @ contentType = Page "text / HTML" pageEncoding = "GBK"%>
<HTML>
<head> <title> www.mldnjava.cn, MLDN high-end Java training </ title> </ head>
<body>
<h3> IP address : $ {pageContext.request.remoteAddr} </ H3>
<H3> the SESSION ID: $ {pageContext.session.id} </h3>
<h3>是否是新session：${pageContext.session.new}</h3>
</body>
</html>
Receiving {param. Request Parameter Name Parameter} $ $ {paramValues.} Parameter name
directly receiving a single output parameter, a plurality of parameters required to specify the index
<%@ page contentType="text/html" pageEncoding="GBK"%>
<html>
<head><title></title></head>
<body>
<%
request.setCharacterEncoding("GBK") ;
%>//参数名为inst
<h3>第一个参数：${paramValues.inst[0]}</h3>
<h3>第二个参数：${paramValues.inst[1]}</h3>
<h3>第三个参数：${paramValues.inst[2]}</h3>
</body>
</html>Collective operation
output collication
<%@ page contentType="text/html" pageEncoding="GBK"%>
<%@ page import="java.util.*"%>
<html>
<head><title> </title></head>
<body>
<%
List all = new ArrayList() ;
all.add("qwe") ;
all.add("www.MLDNJAVA.cn") ;
all.add("[email protected]") ;
request.setAttribute("allinfo",all) ; // 集合保存在request范围
%>
<h3>第一个元素：${allinfo[0]}</h3>
<h3>第二个元素：${allinfo[1]}</h3>
<h3>第三个元素：${allinfo[2]}</h3>
</body>
</html>Map output by $ {info.mldn} or $ {info [ "mldn"]} way
<%@ page contentType="text/html" pageEncoding="GBK"%>
<%@ page import="java.util.*"%>
<html>
<head><title> </title></head>
<body>
<%
Map map = new HashMap() ;
map.put("qwe","qwe") ;
map.put("www","www.M.cn") ;
map.put("email","[email protected]") ;
request.setAttribute("info",map) ; // 集合保存在request范围
%>
<h3>KEY为qwe的内容：${info["qwe"]}</h3>
<h3>KEY为www的内容：${info.www}</h3>
<h3>KEY为email的内容：${info["email"]}</h3>
</body>
</html>In MVC application expression language that can be stored in the range of reflection properties of Java objects through direct access content
<%@ page contentType="text/html" pageEncoding="GBK"%>
<%@ page import="org.lxh.eldemo.vo.*"%>
<html>
<head><title> </title></head>
<body>
<% // 现在假设这些代码是由Servlet完成
Dept dept = new Dept() ;
dept.setDeptno(10) ;
dept.setDname(" 教学部") ;
dept.setLoc(" 西城区") ;
request.setAttribute("deptinfo",dept) ;
%>
<h3>部门编号：${deptinfo.deptno}</h3>
<h3>部门名称：${deptinfo.dname}</h3>
<h3>部门位置：${deptinfo.loc}</h3>
</body>
</html>Transfer request attributes Servlet
import com.hsd.eldemo.vo.* ;
import javax.servlet.* ;
import javax.servlet.http.* ;
public class ELServlet extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response) throws java.io.IOException,ServletException{
Dept dept = new Dept() ;
dept.setDeptno(10) ;
dept.setDname(" 教学部") ;
dept.setLoc(" 西城区") ;
request.setAttribute("deptinfo",dept) ;
request.getRequestDispatcher("dept_info.jsp").forward(request,response) ;
}
public void doPost(HttpServletRequest request,HttpServletResponse response) throws java.io.IOException,ServletException{
this.doGet(request,response) ;
}
}// JSP reception
<%@ page contentType="text/html" pageEncoding="GBK"%>
<html>
<head><title> </title></head>
<body>
<h3>部门编号：${deptinfo.deptno}</h3>
<h3>部门名称：${deptinfo.dname}</h3>
<h3>部门位置：${deptinfo.loc}</h3>
</body>
</html>