JSTL的if标签和forEach标签(页码EL2)

╰半橙微兮° 2023-07-18 14:00 35阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwOTIyODQ1_size_16_color_FFFFFF_t_70]  
导入jstl标签库

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

if标签

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
        pageEncoding="ISO-8859-1"%>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    <title>Insert title here</title>
    </head>
    <body>
    	<%
    		request.setAttribute("test", 10);
    	%>	
    	
    	
    	<c:if test="${test==10}">
    		TTTT
    	</c:if>
    	<c:if test="${test!=10 }">
    		FFFF
    	</c:if>
    </body>
    </html>

for标签

<c:forEach begin="0" end="5" var="i">
    		${i }<br>
    	</c:forEach>

foreach标签使用

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
        pageEncoding="ISO-8859-1"%>
    <%@ page import="java.util.*" %>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
    <%@ page import="cn.aynortechnology.domain.*" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    <title>Insert title here</title>
    </head>
    <body>
    	<%
    		//模拟List<String> strList
    		List<String> strList = new ArrayList<String>();
    		strList.add("itcast");
    		strList.add("aynor");
    		strList.add("boxuegu");
    		strList.add("shandingyu");
    		request.setAttribute("strList", strList);
    		
    		//遍历List<User>内的值
    		List<User> userlist = new ArrayList<User>();
    		User user1 = new User();
    		user1.setId(1);
    		user1.setName("aynor");
    		user1.setPassword("20190222**");
    		userlist.add(user1);
    		User user2 = new User();
    		user2.setId(1);
    		user2.setName("aynor");
    		user2.setPassword("20190222**");
    		userlist.add(user2);
    		application.setAttribute("userlist", userlist);
    		
    		//遍历Map<String,String>的值
    		Map<String,String> strMap = new HashMap<String,String>();
    		strMap.put("name","ayonr");
    		strMap.put("age","21");
    		session.setAttribute("strMap", strMap);
    		
    		//遍历Map<String,User>的值
    		Map<String,User> userMap = new HashMap<String,User>();
    		userMap.put("user1",user1);
    		userMap.put("user2",user2);
    		session.setAttribute("userMap", userMap);
    		
    	%>
    	<h1>取出strList的数据</h1>
    	<c:forEach items="${strList }" var="str">
    		${str }<br>
    	</c:forEach>
    	<h1>取出userList的数据</h1>
    	<c:forEach items="${userlist }" var="user">
    		user的name:${user.name }----user的password:${user.password }<br>
    	</c:forEach>
    	<h1>取出strMap的数据</h1>
    	<c:forEach items="${strMap }" var="entry">
    		${entry.key }:${entry.value }<br>
    	</c:forEach>
    	<h1>取出userMap的数据</h1>
    	<c:forEach items="${userMap }" var="entry">
    		${entry.key }:${enrty.value.name }<br>
    	</c:forEach>
    </body>
    </html>

[(页码EL1)EL表达式、使用EL获取域中数据、EL内置对象、动态获取项目名称][EL1_EL_EL_EL]  
[(页码EL2)JSTL的if标签和forEach标签][EL2_JSTL_if_forEach]  
[(页码EL3)MVC模式和三层架构][EL3_MVC]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwOTIyODQ1_size_16_color_FFFFFF_t_70]: /images/20230528/d171f6870b854e319d73623f67f9213a.png
[EL1_EL_EL_EL]: https://blog.csdn.net/qq_40922845/article/details/105162843
[EL2_JSTL_if_forEach]: https://blog.csdn.net/qq_40922845/article/details/105166597
[EL3_MVC]: https://blog.csdn.net/qq_40922845/article/details/105168274