java.lang.ClassNotFoundException: javax.servlet.jsp.jstl.core.LoopTag 错误

Question

实际上我正在制作一个 Java MVC 项目，我已将 Apache 中的 taglibs.standard.impl.jar 添加到 Tomcat 的 lib 中，并将其添加到 Java 构建路径中。我也尝试了其他方法，但它们没有成功，并且 Eclipse IDE 没有识别标签。现在虽然标签已被识别，但运行应用程序时出现此错误。

SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.ClassNotFoundException: javax.servlet.jsp.jstl.core.LoopTag
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1707)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at org.apache.jasper.compiler.Parser.parseCustomTag(Parser.java:1223)
at org.apache.jasper.compiler.Parser.parseElements(Parser.java:1452)
at org.apache.jasper.compiler.Parser.parse(Parser.java:138)
at org.apache.jasper.compiler.ParserController.doParse(ParserController.java:242)
at org.apache.jasper.compiler.ParserController.parse(ParserController.java:102)
at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:198)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:373)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:353)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:340)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:657)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:357)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:748)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:486)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:411)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:338)
at in.ciat.vidya.controller.StudentLogin.doPost(StudentLogin.java:67)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)

我的输出 jsp 代码如下：

<%@page import="java.util.ArrayList"%>
<%@page import="in.ciat.vidya.model.Student"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"           "http://www.w3.org/TR/html4/loose.dtd">
<%if(session==null){
response.sendRedirect("Login.jsp");

} 

ArrayList al =(ArrayList)request.getAttribute("al");

Object[] arr =al.toArray();

String[] starr={"Student Id: ", "First Name: ","Middle Name: ","Last Name: ","Sex: ","Date of Birth: ", "Address: ","City: ","State: ", "Country: ", "PIN: ","e-mail: ", "Mobile No.: ","Alternate No.: ", "Institute Id: ","Discipline: ","Semester: " ,"Password: ","Photo:" ,"Emergency Contact Name: " ,"Emergency Contact Relation: ","Emergency Contact No.: ", "Last Login Date: " };
%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Student Profile</title>
</head>
<body>

    <c:forEach var="value" items="${arr}" varStatus="status">
        ${starr[status.count]}: ${value}
    </c:forEach> 

    City: <c:out value=”${user.address.city}” default=”N/A”/>

<%--   or u can use      Student Id: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         First Name: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Middle Name: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Last Name: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Sex: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Date of Birth: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Address: <c:out value=”${}” default=”N/A”/><br />  --%>
<%--         City:<c:out value=”${}” default=”N/A”/><br />  --%>
<%--         State: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Country: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         PIN: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         e-mail: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Mobile No.: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Alternate No.: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Institute Id: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Discipline: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Semester: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Password: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Photo: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Emergency Contact Name: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Emergency Contact Relation: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Emergency Contact No.: <c:out value=”${}” default=”N/A”/><br /> --%>
<%--         Last Login Date: <c:out value=”${}” default=”N/A”/><br /> --%>
</body>
</html>

Answer 1

jstl 运行时类路径中缺少 jar 文件。

Download the jstl jar，并将其放入您的应用程序WEB-INF/lib 文件夹中。