java.lang.ClassNotFoundException: javax.servlet.jsp.jstl.core.ConditionalTagSupport

java.lang.ClassNotFoundException: javax.servlet.jsp.jstl.core.ConditionalTagSupport

at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1702)

at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)

at java.lang.ClassLoader.defineClass1(Native Method)

at java.lang.ClassLoader.defineClass(Unknown Source)

at java.security.SecureClassLoader.defineClass(Unknown Source)

at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2928)

at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1174)

at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1669)

at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1547)

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:728)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)

at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:487)

at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:412)

at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)

at org.study.accountactivate.web.servlet.LoginServlet.doGet(LoginServlet.java:63)

at org.study.accountactivate.web.servlet.LoginServlet.doPost(LoginServlet.java:70)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:409)

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1044)

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)

at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315)

at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

at java.lang.Thread.run(Unknown Source)

就是我少了 jstl.jar。而且上面已经提示了