–EL 簡介
–EL的應用場合
–EL 的基本語法
–EL中的算術運算符
–EL中的關係運算符
–EL中的邏輯運算符
–EL的應用場合
–EL 的基本語法
–EL中的算術運算符
–EL中的關係運算符
–EL中的邏輯運算符
------------------------------START-----------------------------------
? EL簡介
–是一種簡單的表達式語言
–能夠訪問變量、JavaBean的屬性、集合和數組
–能夠進行關係、邏輯和算術運算
–能夠訪問內建對象
–是一種簡單的表達式語言
–能夠訪問變量、JavaBean的屬性、集合和數組
–能夠進行關係、邏輯和算術運算
–能夠訪問內建對象
? EL的應用場合
–在標籤的屬性值中使用:
? <some:tag value=“${expr}” />
–在標籤的屬性值中使用:
? <some:tag value=“${expr}” />
ELJSP.jsp
測試:
測試:
測試:
測試:
看下在JAVABean中如何實現哈~
User.java
ELJSP.jsp
<%@ page language="java" import="java.util.*,com.michael.bean.*" pageEncoding="gbk"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'ELJSP.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%request.setAttribute("URL","http://redking.blog.51cto.com"); %>
<c:out value="${URL }"></c:out><br>
<hr>
URL:<input type="text" value="${URL }"><br>
<hr>
<%request.setAttribute("username","michael"); %>
<c:if test="${username=='admin'}">
<input type="button" value="delete"/>
</c:if>
<c:if test="${username!='admin'}">
<input type="button" value="delete" disabled="disabled"/>
</c:if>
<br><hr>
UserName:${username }<br>
<hr>
<%
User u = new User();
u.setId(1);
u.setName("珊珊");
request.setAttribute("u",u);
%>
ID:${u.id }<br/>
Name:${u.name }<br/>
</body>
</html>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'ELJSP.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<%request.setAttribute("URL","http://redking.blog.51cto.com"); %>
<c:out value="${URL }"></c:out><br>
<hr>
URL:<input type="text" value="${URL }"><br>
<hr>
<%request.setAttribute("username","michael"); %>
<c:if test="${username=='admin'}">
<input type="button" value="delete"/>
</c:if>
<c:if test="${username!='admin'}">
<input type="button" value="delete" disabled="disabled"/>
</c:if>
<br><hr>
UserName:${username }<br>
<hr>
<%
User u = new User();
u.setId(1);
u.setName("珊珊");
request.setAttribute("u",u);
%>
ID:${u.id }<br/>
Name:${u.name }<br/>
</body>
</html>
測試:
? EL 的基本語法
?訪問變量
–${變量名稱}
?訪問maps、lists、arrays ,使用“[]”
–customerList[0]
?訪問變量
–${變量名稱}
?訪問maps、lists、arrays ,使用“[]”
–customerList[0]
測試:
Customer.java
Name.java
ELJSP.jsp
測試:
? EL中的算術運算符
– "+"
– "-"
– "*"
– "/"
– "%"
? EL中的關係運算符
–“== ” or “eq”
–“!=“ or “ne”
–“<“ or “lt”
–“>” or “gt”
–“<=“ or “le”
–“>=“ or “ge”
? EL中的邏輯運算符
–“&&” and “and”
–“||” and “or”
–“!” and “not”
– "+"
– "-"
– "*"
– "/"
– "%"
? EL中的關係運算符
–“== ” or “eq”
–“!=“ or “ne”
–“<“ or “lt”
–“>” or “gt”
–“<=“ or “le”
–“>=“ or “ge”
? EL中的邏輯運算符
–“&&” and “and”
–“||” and “or”
–“!” and “not”
測試:
------------------------------------END--------------------------------