EL&&JSTL使用

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EL标签

1.新建el.jsp

<%@pageimport="java.util.ArrayList"%>

<%@pageimport="java.util.List"%>

<%@pageimport="java.util.HashMap"%>

<%@pageimport="java.util.Map"%>

<%@pageimport="p1123.Books"%>

<%@ page language="java"contentType="text/html;charset=UTF-8"

pageEncoding="UTF-8"%>

Stringpath = request.getContextPath();

StringbasePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

pageContext.setAttribute("ctx", basePath);

request.setAttribute("username","zhangsan_request");

session.setAttribute("username","zhangsan_session");

application.setAttribute("username","zhangsan_app");

Booksbooks = new Books();

books.setName("think in java");

pageContext.setAttribute("book", books);

Map names = newHashMap();

names.put("one","LiYang");

names.put("two","WangHua");

pageContext.setAttribute("names",names);

List ages = newArrayList();

ages.add(123);

ages.add(456);

pageContext.setAttribute("ages",ages);

<!DOCTYPEhtmlPUBLIC "-//W3C//DTDHTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<basehref="<%=basePath%>">

<metahttp-equiv="Content-Type"content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

<h3>从不同范围取值</h3>

${ctx} <br>

${username}<br>

${applicationScope.username}<br>

复合对象的属性提取<br>

${book.name}=${book['name'] }

<h3>Map操作</h3>

${names['one']}

${ages[1]}

<h3>el的范围前缀可以省略，可以是四个范围，还可以是：param/params</h3>

${param.name} = request.getParameter("name");

</body>

</html>

2.访问地址

http://localhost:8085/Practise/p1123/el.jsp?name=12

3.效果

JSTL标签

1.新建jstl.jsp

<%@ page language="java"contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

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

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

<!DOCTYPEhtmlPUBLIC "-//W3C//DTDHTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<basehref="<%=basePath%>">

<metahttp-equiv="Content-Type"content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

${param.age }

int age = Integer.parseInt(request.getParameter("age"));

if(age>40)

out.print("中年");

else

out.print("青年");

<h3>JSTL配合EL表达式将大大简化代码</h3>

<c:iftest="${param.age>50 }">

中年

</c:if>

<c:iftest="${param.age<50 }">

青年

</c:if>

<c:setvar="example"value="${100+1}"scope="session" />

<c:outvalue="${example}"default="1000"/>==${example}

<c:setvar="example"value="《》&&&<>" scope="session" />

<c:outvalue="${example}"escapeXml="true"/>

<c:removevar="example"scope="session"/>

String[] strArr = new String[]{"a","b","c","d"} ;

request.setAttribute("list", strArr);

<tableborder="1">

<trstyle="">

</tr>

<c:forEachitems="${list }"var="item"varStatus="status">

<tr

<c:iftest="${status.index%2==0}">style="background-color:red;"</c:if>>

</tr>

</c:forEach>

</table>

</body>

</html>

2.访问地址

http://localhost:8085/Practise/p1123/jstl.jsp?age=12

3.效果

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