1、问题：

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:354) ~[HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:202) ~[HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:473) [HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:554) [HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) [HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-3.4.2.jar:na]

at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:158) [spring-jdbc-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:116) [spring-jdbc-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79) [spring-jdbc-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:324) [spring-jdbc-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.boot.jdbc.EmbeddedDatabaseConnection.isEmbedded(EmbeddedDatabaseConnection.java:120) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.autoconfigure.orm.jpa.HibernateDefaultDdlAutoProvider.getDefaultDdlAuto(HibernateDefaultDdlAutoProvider.java:42) [spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration.lambda$getVendorProperties$1(HibernateJpaConfiguration.java:130) [spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.autoconfigure.orm.jpa.HibernateSettings.getDdlAuto(HibernateSettings.java:41) ~[spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.autoconfigure.orm.jpa.HibernateProperties.determineDdlAuto(HibernateProperties.java:136) ~[spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.autoconfigure.orm.jpa.HibernateProperties.getAdditionalProperties(HibernateProperties.java:102) ~[spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.autoconfigure.orm.jpa.HibernateProperties.determineHibernateProperties(HibernateProperties.java:94) ~[spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration.getVendorProperties(HibernateJpaConfiguration.java:132) [spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration.entityManagerFactory(JpaBaseConfiguration.java:133) ~[spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_144]

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_144]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_144]

at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_144]

at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:651) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:636) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1108) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at com.imooc.SellApplication.main(SellApplication.java:11) ~[classes/:na]

Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_144]

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_144]

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_144]

at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_144]

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.NativeSession.connect(NativeSession.java:144) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:956) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826) ~[mysql-connector-java-8.0.19.jar:8.0.19]

... 48 common frames omitted

Caused by: java.net.ConnectException: Connection timed out: connect

at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method) ~[na:1.8.0_144]

at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85) ~[na:1.8.0_144]

at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_144]

at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_144]

at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_144]

at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172) ~[na:1.8.0_144]

at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_144]

at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_144]

at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65) ~[mysql-connector-java-8.0.19.jar:8.0.19]

... 51 common frames omitted

2020-05-04 01:02:43.163  INFO 7644 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [name: default]

2020-05-04 01:02:43.336  INFO 7644 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate ORM core version 5.4.12.Final

2020-05-04 01:02:43.930  INFO 7644 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.1.0.Final}

2020-05-04 01:02:44.189  INFO 7644 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...

2020-05-04 01:02:44.189  WARN 7644 --- [           main] com.zaxxer.hikari.util.DriverDataSource  : Registered driver with driverClassName=com.mysql.jdbc.Driver was not found, trying direct instantiation.

2020-05-04 01:03:06.195 ERROR 7644 --- [           main] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Exception during pool initialization.

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:354) ~[HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:202) ~[HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:473) [HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:554) [HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) [HikariCP-3.4.2.jar:na]

at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-3.4.2.jar:na]

at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess.obtainConnection(JdbcEnvironmentInitiator.java:180) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:68) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:152) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:176) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:118) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1202) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1233) [hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) [spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) [spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:391) [spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:378) [spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) [spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1855) [spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1792) [spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) [spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) [spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) [spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) [spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) [spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1108) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at com.imooc.SellApplication.main(SellApplication.java:11) ~[classes/:na]

Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_144]

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_144]

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_144]

at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_144]

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.NativeSession.connect(NativeSession.java:144) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:956) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826) ~[mysql-connector-java-8.0.19.jar:8.0.19]

... 49 common frames omitted

Caused by: java.net.ConnectException: Connection timed out: connect

at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method) ~[na:1.8.0_144]

at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85) ~[na:1.8.0_144]

at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_144]

at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_144]

at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_144]

at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172) ~[na:1.8.0_144]

at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_144]

at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_144]

at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155) ~[mysql-connector-java-8.0.19.jar:8.0.19]

at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65) ~[mysql-connector-java-8.0.19.jar:8.0.19]

... 52 common frames omitted

2020-05-04 01:03:06.196  WARN 7644 --- [           main] o.h.e.j.e.i.JdbcEnvironmentInitiator     : HHH000342: Could not obtain connection to query metadata : Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

2020-05-04 01:03:06.201  WARN 7644 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]

2020-05-04 01:03:06.208  INFO 7644 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]

2020-05-04 01:03:06.245  INFO 7644 --- [           main] ConditionEvaluationReportLoggingListener :

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.

2020-05-04 01:03:06.269 ERROR 7644 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1796) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1108) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at com.imooc.SellApplication.main(SellApplication.java:11) [classes/:na]

Caused by: org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:275) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:152) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:176) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:118) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1202) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1233) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) ~[spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:391) ~[spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:378) ~[spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1855) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1792) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

... 16 common frames omitted

Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set

at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.determineDialect(DialectFactoryImpl.java:100) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:54) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:137) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

... 33 common frames omitted

Process finished with exit code 1

原因：ip变了，之前192.168.0.103 ，现在192.168.0.105

9、运行拨错

问题：

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.

2020-05-04 08:07:52.736 ERROR 4964 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'requestMappingHandlerAdapter' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Unsatisfied dependency expressed through method 'requestMappingHandlerAdapter' parameter 1; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mvcConversionService' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.format.support.FormattingConversionService]: Factory method 'mvcConversionService' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productCategoryRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class com.imooc.dataobject.ProductCategory

at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:798) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:539) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:882) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at com.imooc.SellApplication.main(SellApplication.java:11) [classes/:na]

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mvcConversionService' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.format.support.FormattingConversionService]: Factory method 'mvcConversionService' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productCategoryRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class com.imooc.dataobject.ProductCategory

at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:656) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:636) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1290) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1210) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:885) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:789) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

... 19 common frames omitted

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.format.support.FormattingConversionService]: Factory method 'mvcConversionService' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productCategoryRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class com.imooc.dataobject.ProductCategory

at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:651) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

... 33 common frames omitted

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'productCategoryRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class com.imooc.dataobject.ProductCategory

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1796) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1114) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.data.repository.support.Repositories.cacheRepositoryFactory(Repositories.java:99) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.repository.support.Repositories.populateRepositoryFactoryInformation(Repositories.java:92) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.repository.support.Repositories.<init>(Repositories.java:85) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.repository.support.DomainClassConverter.setApplicationContext(DomainClassConverter.java:109) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.web.config.SpringDataWebConfiguration.addFormatters(SpringDataWebConfiguration.java:131) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.web.servlet.config.annotation.WebMvcConfigurerComposite.addFormatters(WebMvcConfigurerComposite.java:81) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.web.servlet.config.annotation.DelegatingWebMvcConfiguration.addFormatters(DelegatingWebMvcConfiguration.java:78) ~[spring-webmvc-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration$EnableWebMvcConfiguration.mvcConversionService(WebMvcAutoConfiguration.java:430) ~[spring-boot-autoconfigure-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_144]

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_144]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_144]

at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_144]

at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

... 34 common frames omitted

Caused by: java.lang.IllegalArgumentException: Not a managed type: class com.imooc.dataobject.ProductCategory

at org.hibernate.metamodel.internal.MetamodelImpl.managedType(MetamodelImpl.java:582) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.hibernate.metamodel.internal.MetamodelImpl.managedType(MetamodelImpl.java:85) ~[hibernate-core-5.4.12.Final.jar:5.4.12.Final]

at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation.<init>(JpaMetamodelEntityInformation.java:74) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.jpa.repository.support.JpaEntityInformationSupport.getEntityInformation(JpaEntityInformationSupport.java:66) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getEntityInformation(JpaRepositoryFactory.java:211) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:161) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:144) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:69) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:312) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.lambda$afterPropertiesSet$5(RepositoryFactoryBeanSupport.java:297) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.util.Lazy.getNullable(Lazy.java:212) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.util.Lazy.get(Lazy.java:94) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:300) ~[spring-data-commons-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:121) ~[spring-data-jpa-2.2.6.RELEASE.jar:2.2.6.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1855) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1792) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]

... 54 common frames omitted

Process finished with exit code 1

2、原因：

实体类没有注释@Entity

3、解决：

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9. com.mysql.cj.jdbc.exceptions.MysqlDataTruncation

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