Connect to mysql to report “com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException” error solution
Database connection failed, solve it
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Full error
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Serious: Servlet.service() for servlet [com.iheima.web.LoginServlet] in context with path [/request-demo] threw exception org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. ### The error may exist in com/iheima/mapper/UserMapper.java (best guess) ### The error may involve com.itheima.mapper.UserMapper.select ### The error occurred while executing a query ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:149) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:76) at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:87) at org.apache.ibatis.binding.MapperProxy$PlainMethodInvoker.invoke(MapperProxy.java:152) at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:85) at com.sun.proxy.$Proxy30.select(Unknown Source) at com.itheima.web.LoginServlet.doGet(LoginServlet.java:38) at com.itheima.web.LoginServlet.doPost(LoginServlet.java:58) 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:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) 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: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.jdbc.Util.handleNewInstance(Util.java:377) at com.mysql.jdbc.Util.getInstance(Util.java:360) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:935) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:924) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:870) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2311) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2064) at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:790) at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.jdbc.Util.handleNewInstance(Util.java:377) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:395) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325) at java.sql.DriverManager.getConnection(DriverManager.java:664) at java.sql.DriverManager.getConnection(DriverManager.java:208) at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.doGetConnection(UnpooledDataSource.java:224) at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.doGetConnection(UnpooledDataSource.java:219) at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.getConnection(UnpooledDataSource.java:95) at org.apache.ibatis.datasource.pooled.PooledDataSource.popConnection(PooledDataSource.java:432) at org.apache.ibatis.datasource.pooled.PooledDataSource.getConnection(PooledDataSource.java:89) at org.apache.ibatis.transaction.jdbc.JdbcTransaction.openConnection(JdbcTransaction.java:139) at org.apache.ibatis.transaction.jdbc.JdbcTransaction.getConnection(JdbcTransaction.java:61) at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:337) at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:86) at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62) at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:325) at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156) at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109) at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:89) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147) ... 29 more Caused by: java.lang.NullPointerException at com.mysql.jdbc.ConnectionImpl.getServerCharset(ConnectionImpl.java:2983) at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1873) at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1802) at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1206) at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2234) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2265) ... 56 more
Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. ### The error may exist in com/iheima/mapper/UserMapper.java (best guess) ### The error may involve com.itheima.mapper.UserMapper.select ### The error occurred while executing a query ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
version issue
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.34</version>
</dependency>
Modified
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.22</version>
</dependency>
October 27, 2022 6:04:54 pm org.apache.coyote.AbstractProtocol init Info: Initializing ProtocolHandler ["http-bio-8080"] October 27, 2022 6:04:54 pm org.apache.catalina.core.StandardService startInternal Info: Starting service Tomcat October 27, 2022 6:04:54 pm org.apache.catalina.core.StandardEngine startInternal Info: Starting Servlet Engine: Apache Tomcat/7.0.47 October 27, 2022 6:04:56 pm org.apache.coyote.AbstractProtocol start INFO: Starting ProtocolHandler ["http-bio-8080"]
Hope to help you! ! !