同一个workspace下，有两个工程，用了同样的方法连接数据库，第一个可以正常访问，另外一个却报错了，错误内容如下。
点击错误内容信息，指向的却是第一个工程下面的代码，为什么啊？百思不得其解。
自己觉得，这个错是JDBC驱动跟sql的版本不匹配报的错。自己检查，我的数据库是mysql8，应该就是这个驱动。而且第一个工程是能够正常访问的，为什么第二个工程就不行了？
严重: dataSource init error
java.sql.SQLException: com.mysql.cj.jdbc.Driver
at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:520)
at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:583)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:915)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:911)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:98)
at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:158)
at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:116)
at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79)
at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:612)
at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:669)
at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:700)
at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:712)
at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java:790)
at cn.itcast.dao.UserDao.login(UserDao.java:27)
at cn.itcast.sessiontest.loginServlet.doGet(loginServlet.java:51)
at cn.itcast.sessiontest.loginServlet.doPost(loginServlet.java:77)
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: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:221)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:107)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:76)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:934)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:90)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1015)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:646)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1576)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1534)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1286)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1128)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:518)
... 38 more
六月 21, 2020 8:42:25 下午 com.alibaba.druid.pool.DruidDataSource info
信息: {dataSource-1} inited
下面是工程目录机构，第一个项目是指：day14_test项目
报错的是第二个项目：day16_cookie&session
