今天写SpringMvc时，遇到这样一个问题：
java.lang.NoClassDefFoundError: javax/servlet/jsp/jstl/core/Config
at org.springframework.web.servlet.support.JstlUtils.exposeLocalizationContext(JstlUtils.java:101) at org.springframework.web.servlet.view.JstlView.exposeHelpers(JstlView.java:135) at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:142) at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:303) at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1244) at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1027) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:971) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:85) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454) at java.lang.Thread.run(Thread.java:619)于是思考了半天，终于找出来了，原来少导了jstl.jar.和standard.jar这两个jar包
jstl.jar.
<dependency>
<groupId>javax.servlet</groupId><artifactId>jstl</artifactId><version>1.2</version></dependency> standard.jar<dependency><groupId>taglibs</groupId><artifactId>standard</artifactId><version>1.1.2</version></dependency>这两个jar包又有什么作用呢？
standard.jar的作用
JSP 标准标签库，和jstl.jar 一起使用，在1.0的版本中，但在jstl-1.2.jar 就不在需要了。如果你想在项目中使用JSTL和EL表达式，那么你必须要引入这个standard.jar文件。即使你没有引入，那MyEclipse工具自带的类库也会帮你倒入。