无法加载 JDBC 驱动程序类“com.mysql.cj.jdbc.driver”答案

【问题标题】：Cannot load JDBC driver class 'com.mysql.cj.jdbc.driver'无法加载 JDBC 驱动程序类“com.mysql.cj.jdbc.driver”
【发布时间】：2018-05-09 12:23:35
【问题描述】：

我是一名 Spring MVC 初学者，使用 Tomcat 9 和 Eclipse 来运行 Spring 应用程序。我在运行时收到以下错误。

org.apache.jasper.JasperException: An exception occurred processing JSP page [/WEB-INF/views/listOrganization1.jsp] at line [13]

    10: </head>
    11: <body>
    12:     <h1>Listing organizations using JSTL SQL tag</h1>
    13:     <sql:query var="rs" dataSource="jdbc/springdb">
    14:         SELECT * FROM organization
    15:     </sql:query>
    16:     


    Stacktrace:
        org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:588)
        org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:466)
        org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
        org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:170)
        org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:314)
        org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325)
        org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069)
        org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008)
        org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
        org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
        org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:870)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
        org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)


    Root Cause
    javax.servlet.ServletException: javax.servlet.jsp.JspException: Unable to get connection, DataSource invalid: "java.sql.SQLException: Cannot load JDBC driver class 'com.mysql.cj.jdbc.driver'"
        org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:669)
        org.apache.jsp.WEB_002dINF.views.listOrganization1_jsp._jspService(listOrganization1_jsp.java:156)
        org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
        org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
        org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:170)
        org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:314)
        org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325)
        org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069)
        org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008)
        org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
        org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
        org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:870)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
        org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)


    Root Cause
    javax.servlet.jsp.JspException: Unable to get connection, DataSource invalid: "java.sql.SQLException: Cannot load JDBC driver class 'com.mysql.cj.jdbc.driver'"
        org.apache.taglibs.standard.tag.common.sql.QueryTagSupport.getConnection(QueryTagSupport.java:285)
        org.apache.taglibs.standard.tag.common.sql.QueryTagSupport.doStartTag(QueryTagSupport.java:168)
        org.apache.jsp.WEB_002dINF.views.listOrganization1_jsp._jspx_meth_sql_005fquery_005f0(listOrganization1_jsp.java:180)
        org.apache.jsp.WEB_002dINF.views.listOrganization1_jsp._jspService(listOrganization1_jsp.java:135)
        org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
        org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
        org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:170)
        org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:314)
        org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1325)
        org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1069)
        org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008)
        org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
        org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
        org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:870)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
        org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:855)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

但是mysql-connector-java-6.0.6.jar已经作为Maven依赖存在于项目中

而且context.xml对于Tomcat已经有了数据库信息作为资源

<?xml version="1.0" encoding="UTF-8"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
--><!-- The contents of this file will be loaded for each web application --><Context>

    <!-- Default set of monitored resources. If one of these changes, the    -->
    <!-- web application will be reloaded.                                   -->
    <WatchedResource>WEB-INF/web.xml</WatchedResource>
    <WatchedResource>${catalina.base}/conf/web.xml</WatchedResource>

    <!-- Uncomment this to disable session persistence across Tomcat restarts -->
    <!--
    <Manager pathname="" />
    -->

    <Resource name="jdbc/springdb" auth="Container" type="javax.sql.DataSource"
               maxTotal="100" maxIdle="30" maxWaitMillis="10000"
               username="devuser" password="$Data4Dev" driverClassName="com.mysql.cj.jdbc.driver"
               url="jdbc:mysql://localhost:3306/spring_db?useSSL=false"/>

</Context>

根据此处对另一个问题的回复，我还将 mysql-connector jar 添加到 Tomcat 9 服务器的运行时配置中。

我还多次删除了 C:\Users\user1.m2\repository 中的存储库，关闭并打开了 Eclipse 并更新了项目的 Maven - 没有任何效果，我一直收到同样的错误。

【问题讨论】：

尝试将driver 中的d 大写在com.mysql.cj.jdbc.driver 的末尾。
您不应该使用 MySQL Connector/J 6.0.6。它是 已放弃 Connector/J 6 分支的开发/测试版本（它们继续在尚未发布的 Connector/J 8 开发分支中）。 MySQL的最新版本还是5.1.44
另外，永远不要使用 sql 标签库。如果您从视图内部执行 SQL 查询，那么您真的错过了 MVC 的全部意义。控制器从数据库中获取数据，将其存储在模型中，并将控制权交给视图，视图显示模型中的数据。这就是 MVC 的基本原理。
我之前的评论应该是“MySQL Connector/J的最新版本还是5.1.44”
@MarkRotteveel 感谢您提供信息。将在我的项目上更新它。

标签： mysql eclipse maven spring-mvc jdbc

【解决方案1】：

检查构建路径库中添加的 MySQL 连接器 jar 版本。我在构建路径库中添加了旧 jar。这已通过更改构建路径库中的 jar 得到修复。

对你来说可能不是这样。因为 Maven 会自动将 jars 添加到构建路径库中。

以上答案适用于在没有maven帮助的情况下手动创建项目的人。

【讨论】：

【解决方案2】：

通过进行 Luke Woodward 建议的更改已解决此问题。

【讨论】：