![\"el6\"](\"https:\/\/ai.zhousir.top\/wp-content\/uploads\/2016\/12\/el6.jpeg\")
<\/a><\/p>\n\u5bf9empty\u4e3e\u4f8b\uff1a<\/p>\n
[java]<% String username="null"; request.setAttribute("username", username); %>
\n<c:out value="${empty username}"><\/c:out>
\nPs\uff1a\u5982\u679cusername\u4e3anull\u6216\u8005""\uff0c\u5219\u8fd4\u56detrue\uff1b\u5982\u679cusername\u4e3a"\u6709\u5185\u5bb9"\uff0c\u5219\u8fd4\u56defalse\u3002<\/p>\n
el\u8868\u8fbe\u5f0f\u4e2dempty\u8fd0\u7b97\u7b26\u5bf9\u5b57\u7b26\u4e32\u4e3aNull\uff0c\u53ca\u7a7a\u5b57\u7b26\u4e32\u90fd\u8fd4\u56de TRUE\u3002[\/java]<\/p>\n
\u4e09\u3001JSTL\u6838\u5fc3\u6807\u7b7e\u5e93\u4f7f\u7528<\/h2>\n
JSTL \u6838\u5fc3\u6807\u7b7e\u5e93\u6807\u7b7e\u5171\u670913\u4e2a\uff0c\u529f\u80fd\u4e0a\u5206\u4e3a4\u7c7b\uff1a<\/p>\n
[java]1.\u8868\u8fbe\u5f0f\u63a7\u5236\u6807\u7b7e\uff1aout\u3001set\u3001remove\u3001catch<\/p>\n
2.\u6d41\u7a0b\u63a7\u5236\u6807\u7b7e\uff1aif\u3001choose\u3001when\u3001otherwise<\/p>\n
3.\u5faa\u73af\u6807\u7b7e\uff1aforEach\u3001forTokens<\/p>\n
4.URL\u64cd\u4f5c\u6807\u7b7e\uff1aimport\u3001url\u3001redirect<\/p>\n
\u4f7f\u7528\u6807\u7b7e\u65f6\uff0c\u4e00\u5b9a\u8981\u5728jsp\u6587\u4ef6\u5934\u52a0\u5165\u4ee5\u4e0b\u4ee3\u7801\uff1a<\/p>\n
<%@taglib prefix="c" uri="http:\/\/java.sun.com\/jsp\/jstl\/core" %>[\/java]<\/p>\n
1\u3001out\u6807\u7b7e(\u8868\u8fbe\u5f0f\u63a7\u5236\u6807\u7b7e)<\/h3>\n
out\u6807\u7b7e\u7684\u4f5c\u7528\uff1a<\/p>\n
\t[java]
\n <c:out value="23" default="20"><\/c:out>
\n\t<c:out value="${age}" default="20"><\/c:out>[\/java]<\/p>\n
2\u3001set\u6807\u7b7e(\u8868\u8fbe\u5f0f\u63a7\u5236\u6807\u7b7e)<\/h3>\n
set\u7684\u6807\u7b7e\u7684\u4f5c\u7528\uff1a<\/p>\n
\u5b58\u503c\u5230scope\u4e2d(page,request,session,application)\uff1b
\n\u53ef\u4ee5\u5c06\u503c\u4ee5\u53d8\u91cf\u5f62\u5f0f\u5b58\u653e\u5728\u6307\u5b9a\u8303\u56f4\u5185\uff0c\u6709\u4e24\u79cd\u65b9\u5f0f\uff1a
\n[java]<c:set var="age" value="23" scope="session" \/> \t<%– <c:set var="age" scope="session">23<\/c:set>–%>
\n<h1><c:out value="\u4e09\u3001set\u6807\u7b7e\u7ed9javaBean\u5c5e\u6027\u8d4b\u503c"><\/c:out><\/h1>
\n\t<jsp:useBean id="person" class="com.ittx.entity.Person" scope="page" \/>
\n\t<c:set target="${person}" property="name" value="\u9ebb\u5b50"><\/c:set>
\n\t<c:out value="${person.name}" \/>
\n\t<%– <jsp:setProperty property="name" name="person" value="\u5c0f\u660e11"\/> –%>
\n\t<%– <jsp:getProperty property="name" name="person" \/> –%>[\/java]<\/p>\n
3\u3001remove\u6807\u7b7e(\u8868\u8fbe\u5f0f\u63a7\u5236\u6807\u7b7e)<\/h3>\n
remove\u6807\u7b7e\u7684\u7528\u6cd5\uff1a<\/p>\n
\u53ea\u80fdremove\u6389\u67d0\u4e2a\u53d8\u91cf\uff08\u4e0d\u80fdremove\u67d0\u4e2a\u7c7b\u5bf9\u8c61\u7684\u67d0\u4e2a\u5c5e\u6027\uff09\uff1b
\nvar\u5c5e\u6027\u662f\u5fc5\u9009\uff1b
\nscope\u5c5e\u6027\u662f\u53ef\u9009\u3002<\/p>\n
[java]<c:set var="firstName" value="\u5c0f\u660e"><\/c:set>
\n\t<c:remove var="firstName" \/>[\/java]<\/p>\n
4\u3001catch\u6807\u7b7e(\u8868\u8fbe\u5f0f\u63a7\u5236\u6807\u7b7e)<\/h3>\n
catch\u6807\u7b7e\u7684\u7528\u6cd5\uff1a<\/p>\n
catch\u6807\u7b7e\u4e2d\u53ef\u4ee5\u5305\u542b\u90a3\u4e9b\u5bb9\u6613\u51fa\u9519\u7684JSTL\u6807\u7b7e\uff08\u903b\u8f91\uff09
\n[java]<c:catch var="error">
\n\t\t<c:set target="user" property="firstName" value="lili"><\/c:set>
\n\t<\/c:catch>
\n\t<c:out value="${error}"><\/c:out>[\/java]<\/p>\n
5\u3001if\u6807\u7b7e(\u6d41\u7a0b\u63a7\u5236\u6807\u7b7e)<\/h3>\n
if\u6807\u7b7e\u7684\u7528\u6cd5\uff1a<\/p>\n
\u540c\u7a0b\u5e8f\u4e2d\u7684if\u4f5c\u7528\u76f8\u540c\uff0c\u7528\u6765\u5b9e\u73b0\u5206\u652f\u6761\u4ef6\u63a7\u5236\u3002
\ntest\u5c5e\u6027\u7528\u4e8e\u5b58\u653e\u5224\u65ad\u7684\u6761\u4ef6\uff0c\u4e00\u822c\u4f7f\u7528EL\u8868\u8fbe\u5f0f\u6765\u7f16\u5199\u3002
\nvar\u6307\u5b9a\u540d\u79f0\u7528\u6765\u5b58\u653e\u5224\u65ad\u7684\u7ed3\u679c\u7c7b\u578b\u4e3atrue\u6216false
\nscope\u7528\u6765\u5b58\u653evar\u5c5e\u6027\u5b58\u653e\u7684\u8303\u56f4\u3002
\n<\/c:if><\/p>\n\u6bd4\u5982\uff1a\u6839\u636e\u7528\u6237\u8f93\u5165\u7684\u6210\u7ee9\u8fdb\u884c\u7b49\u7ea7\u5224\u65ad
\n[java]<c:if test="${param.score >= 90}" var="result">
\n\t\t<c:out value="\u6210\u7ee9\u4f18\u5f02!"><\/c:out>
\n\t<\/c:if><\/p>\n
\t<c:out value="${result}"><\/c:out>[\/java]<\/p>\n
6\u3001choose\u3001when\u3001otherwise(\u6d41\u7a0b\u63a7\u5236\u6807\u7b7e)<\/h3>\n
\u00a0choose\u3001when\u3001otherwise \u6807\u7b7e\u7684\u4f5c\u7528\uff1a<\/p>\n
\u901a\u5e38\u8fd9\u4e09\u4e2a\u6807\u7b7e\u88ab\u653e\u5728\u4e00\u8d77\u914d\u5408\u4f7f\u7528
\n\u6807\u7b7e\u5d4c\u5957\u5728\u548c\u6807\u7b7e\u7684\u5916\u9762\u4f5c\u4e3a\u4ed6\u4eec\u7684\u7236\u6807\u7b7e\u6765\u4f7f\u7528\u3002\u00a0
\n\u5176\u4e2dchoose\u548cwhen\u6807\u7b7e\u4e5f\u53ef\u4ee5\u4e00\u8d77\u7ec4\u5408\u4f7f\u7528\u3002
\n\u7efc\u4e0a\u6240\u8ff0\u901a\u5e38\u6709\u4ee5\u4e0b\u4e24\u79cd\u8bed\u6cd5\u7ed3\u6784\uff1a
\n[java]<c:choose>
\n\t\t\t<c:when test="${param.score<=100 && param.score>=60 }">
\n\t\t\t\t<c:out value="\u53ca\u683c"><\/c:out>
\n\t\t\t<\/c:when>
\n\t\t\t<c:when test="${param.score<60 && param.score>=0 }">
\n\t\t\t\t<c:out value="\u4e0d\u53ca\u683c"><\/c:out>
\n\t\t\t<\/c:when>
\n\t\t\t<c:otherwise>
\n\t\t\t\t<c:out value="\u8bf7\u68c0\u67e5\u4f60\u7684\u8f93\u5165\uff01"><\/c:out>
\n\t\t\t<\/c:otherwise>
\n\t\t<\/c:choose>[\/java]<\/p>\n7\u3001forEach(\u5faa\u73af\u63a7\u5236\u6807\u7b7e)\u548cforTokens(\u5faa\u73af\u63a7\u5236\u6807\u7b7e)<\/h3>\n
forEach\u6807\u7b7e\u7684\u4f5c\u7528\uff1a
\n[java]<h1>forEach<\/h1><\/p>\n
\t<%
\n\t\tArrayList<String> lists = new ArrayList();
\n\t\tlists.add("one");
\n\t\tlists.add("two");
\n\t\tlists.add("three");
\n\t\tlists.add("four");
\n\t\tsession.setAttribute("list", lists);<\/p>\n
\t%>
\n\t<c:forEach items="${sessionScope.list}" var="item" begin="1" end="3">
\n\t\t<c:out value="${item}"\/>
\n\t<\/c:forEach><\/p>\n
\t<br><hr>
\n\t<h1>forTokens<\/h1>
\n\t<%
\n\t\tString noUrl = "login.jsp;login.do;loginout.jsp;register.jsp";
\n\t\tsession.setAttribute("noUrl", noUrl);
\n\t%>
\n\t<c:forTokens items="${sessionScope.noUrl}" delims=";" var="item">
\n\t\t<c:out value="${item}"\/><br>
\n\t<\/c:forTokens>[\/java]<\/p>\n
9\u3001URL\u64cd\u4f5c\u6807\u7b7e<\/h3>\n
import,redirect\u6807\u7b7e,url\u6807\u7b7e<\/p>\n
[java]<%– <jsp:include page=".\/index.jsp"><\/jsp:include> –%>
\n\t<c:import url="http:\/\/www.baidu.com" charEncoding="utf-8"><\/c:import><\/p>\n
\t<br><hr>
\n\t<h1>redirect<\/h1>
\n\t<%– <c:redirect url=".\/index.jsp">
\n\t\t<c:param name="userName" value="10"><\/c:param>
\n\t<\/c:redirect> –%><\/p>\n
\t<br><hr>
\n\t<h1>url<\/h1>
\n\t<c:url var="main" value="http:\/\/192.168.5.3:8080\/Jstl\/index.jsp">
\n\t\t<c:param name="userName" value="11"><\/c:param>
\n\t\t<c:param name="passWord" value="123456"><\/c:param>
\n\t<\/c:url><\/p>\n
\t<c:out value="${main}"><\/c:out><\/p>\n
\t<a href="${main}">\u9996\u9875<\/a>[\/java]<\/p>\n
\u56db\u3001JSTL\u51fd\u6570\u4f7f\u7528<\/h2>\n1\u3001contains\u51fd\u6570\u3001startsWith\u3001endsWith<\/h3>\n
contains\u51fd\u6570\u8868\u793a\u52a0\u5165\u7684\u5b57\u7b26\u4e32\u662f\u5426\u5305\u542b\u5b57\u4e32\uff0c\u8fd4\u56de\u4e00\u4e2aboolean\u7c7b\u578b\u7684\u503c\u3002<\/p>\n
Ps1\uff1a\u914d\u5408\u4f7f\u7528\uff1a
\n<%@ taglib uri=\"http:\/\/java.sun.com\/jsp\/jstl\/core\" prefix=\"c\"%>
\n<%@ taglib uri=\"http:\/\/java.sun.com\/jsp\/jstl\/functions\" prefix=\"fn\"%><\/p>\n
2\u3001escapeXml\u3001indexOf<\/h3>\n
[java]<c:out
\n\t\tvalue="\u201cHello World\u201d\u5b57\u7b26\u4e32\u4e2d\u662f\u5426\u5305\u542b\u201cHello\u201d?${fn:contains(‘Hello World’,’Hello’)}"><\/c:out>
\n\t<hr>
\n\t<c:out
\n\t\tvalue="\u201cHello World\u201d\u5b57\u7b26\u4e32\u4e2d\u662f\u5426\u5305\u542b\u201cABCD\u201d?${fn:contains(‘Hello World’,’ABCD’)}"><\/c:out>
\n\t<hr>
\n\t<c:out
\n\t\tvalue="\u201cHello World\u201d\u5b57\u7b26\u4e32\u4e2d\u662f\u5426\u5305\u542b\u201chello\u201d\uff08\u5ffd\u7565\u5927\u5c0f\u5199\uff09?${fn:containsIgnoreCase(‘Hello World’,’hello’)}"><\/c:out>
\n\t<hr>
\n\t<c:out
\n\t\tvalue="\u201cHello\u201d\u662f\u5426\u5728\u201cHello World\u201d\u5b57\u7b26\u4e32\u5f00\u5934?${fn:startsWith(‘Hello World’,’Hello’)}"><\/c:out>
\n\t<hr>
\n\t<c:out
\n\t\tvalue="\u201cworld\u201d\u662f\u5426\u5728\u201cHello World\u201d\u5b57\u7b26\u4e32\u5c3e\u90e8?${fn:endsWith(‘Hello World’,’world’)}"><\/c:out><\/p>\n
\t<c:out value="${fn:indexOf(‘helloworld’,’java’)}"><\/c:out>\t<\/p>\n
<c:out value="${fn:escapeXml(‘<book>\u4e66<\/book>’)}"><\/c:out>
\n <c:out value="<book>\u4e66<\/book>"><\/c:out>[\/java]
\n![\"h1\"](\"https:\/\/ai.zhousir.top\/wp-content\/uploads\/2016\/12\/h1.jpeg\")
<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"\u76ee\u5f55\u7ed3\u6784 [java]\u4e00\u3001JSTL\u7b80\u4ecb\u548c\u73af\u5883\u914d\u7f6e 1\u3001\u4ec0\u4e48\u662fJSTL 2\u3001\u4e3a\u4ec0\u4e48\u8981\u4f7f\u7528JSTL 3\u3001JSTL\u73af […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[87],"tags":[],"_links":{"self":[{"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/posts\/1860"}],"collection":[{"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1860"}],"version-history":[{"count":7,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/posts\/1860\/revisions"}],"predecessor-version":[{"id":1874,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=\/wp\/v2\/posts\/1860\/revisions\/1874"}],"wp:attachment":[{"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1860"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1860"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ai.zhousir.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1860"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"el1\"](\"https:\/\/ai.zhousir.top\/wp-content\/uploads\/2016\/12\/el1.jpeg\")
<\/a><\/p>\n