JFinal 报错 init datasource error, url: jdbc:mysql://localhost........

错误：

十月 17, 2017 2:25:03 下午 com.alibaba.druid.pool.DruidDataSource error
严重: init datasource error, url: jdbc:mysql://localhost/jfinal_demo
java.sql.SQLException: java.lang.IllegalAccessError: class sun.reflect.GeneratedConstructorAccessor1 cannot access its superclass sun.reflect.ConstructorAccessorImpl
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:435)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:389)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1461)
at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1525)
at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:734)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1060)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1056)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:104)
at com.jfinal.plugin.activerecord.TableBuilder.build(TableBuilder.java:43)
at com.jfinal.plugin.activerecord.ActiveRecordPlugin.start(ActiveRecordPlugin.java:226)
at com.jfinal.core.Config.startPlugins(Config.java:107)
at com.jfinal.core.Config.configJFinal(Config.java:53)
at com.jfinal.core.JFinal.init(JFinal.java:63)
at com.jfinal.core.JFinalFilter.init(JFinalFilter.java:49)
at org.eclipse.jetty.servlet.FilterHolder.doStart(FilterHolder.java:119)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:724)
at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:265)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:706)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:492)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:95)
at org.eclipse.jetty.server.Server.doStart(Server.java:277)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
at com.jfinal.server.JettyServer.doStart(JettyServer.java:131)
at com.jfinal.server.JettyServer.start(JettyServer.java:70)
at com.jfinal.core.JFinal.start(JFinal.java:157)
at org.jiumi.config.DemoConfig.main(DemoConfig.java:130)

如果你的url没有写错，那么把JFinal.start("WebContent", 80, "/", 5); 的最后一个参数去掉。试试看吧。最新一版的eclipse   

Eclipse Java EE IDE for Web Developers.

Version: Oxygen.1a Release (4.7.1a)
Build id: 20171005-1200 

跟IDEA 一样，需要去掉最后一个参数。