解决访问Tomcat时报java.lang.LinkageError错误

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我是靠谱客的博主发嗲烧鹅，最近开发中收集的这篇文章主要介绍解决访问Tomcat时报java.lang.LinkageError错误，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

今天在VPN上解决其它问题时突然遇到了这么一个奇怪的错误，异常大约如下所示（其它相似异常也可能是该问题）：

exception

javax.servlet.ServletException: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;
" the class loader (instance of org/apache/jasper/servlet/JasperLoader) of the current class, org/apache/jsp/index_jsp, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, 
have different Class objects for the type javax/el/ExpressionFactory used in the signature
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:343)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

root cause

java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/jasper/servlet/JasperLoader) of the current class, org/apache/jsp/index_jsp, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
org.apache.jsp.index_jsp._jspInit(index_jsp.java:31)
org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:49)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:180)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

如果将Web应用移出Tomcat的webapps目录再启动Tomcat则页面可以正常访问，将web项目放进去再访问就报错，后来Google了一下，发现是jar包问题（在此鄙视一下百度），就是说我们自己的应用中不应该包含WEB服务相关的jar包，即 /WEB-INF/lib 目录下不能出现诸如 jsp-api.jar、el-api.jar、servlet-api.jar 等jar包，于是我到自己项目的lib下查看，果然有几个这样的包，如下：