SpringBoot Mysql 数据库无法打开 JDBC 连接进行 DDL 执行

Question

我使用本地 h2 数据库运行我的应用程序。现在我想将它连接到一个在线 mysql 数据库。但是在尝试启动连接时，我多次收到com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure，此外还有以下错误：

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 javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1710) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:583) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1085) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:858) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:752) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:388) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1234) [spring-boot-2.0.0.RELEASE.jar:2.0.0.RELEASE]
at quiz.QuizAppMain.main(QuizAppMain.java:16) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.0.0.RELEASE.jar:2.0.0.RELEASE]
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.persistenceException(EntityManagerFactoryBuilderImpl.java:970) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:895) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:57) ~[spring-orm-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:388) ~[spring-orm-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:377) ~[spring-orm-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1769) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1706) ~[spring-beans-5.0.4.RELEASE.jar:5.0.4.RELEASE]
... 21 common frames omitted
Caused by: org.hibernate.exception.JDBCConnectionException: Unable to open JDBC Connection for DDL execution
at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:115) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl.getIsolatedConnection(DdlTransactionIsolatorNonJtaImpl.java:69) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.internal.exec.ImprovedExtractionContextImpl.getJdbcConnection(ImprovedExtractionContextImpl.java:60) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.internal.exec.ImprovedExtractionContextImpl.getJdbcDatabaseMetaData(ImprovedExtractionContextImpl.java:67) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.extract.internal.InformationExtractorJdbcDatabaseMetaDataImpl.getTables(InformationExtractorJdbcDatabaseMetaDataImpl.java:329) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.extract.internal.DatabaseInformationImpl.getTablesInformation(DatabaseInformationImpl.java:120) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.internal.GroupedSchemaMigratorImpl.performTablesMigration(GroupedSchemaMigratorImpl.java:65) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.performMigration(AbstractSchemaMigrator.java:207) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.doMigration(AbstractSchemaMigrator.java:114) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.performDatabaseAction(SchemaManagementToolCoordinator.java:183) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.process(SchemaManagementToolCoordinator.java:72) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:312) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:460) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:892) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
... 28 common frames omitted
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

我在 pom.xml 中添加了以下内容：

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>

    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.6</version>
    </dependency>

这是我的 application.properties：

spring.datasource.url=jdbc:mysql://my.url.net:port
spring.datasource.username=username
spring.datasource.password=password
spring.datasource.name=dbname
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
spring.jpa.hibernate.ddl-auto=update
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

从 h2 更改为 mysql 时，我没有对源代码进行任何更改，因为我正在实现 CrudRepository，它也应该适用于 mysql。

您能否给我一些提示，可能缺少什么？我已经在 stackoverflow 上检查了类似的问题，但是在添加了几种解决方案之后（例如添加 hibernate.dialect 和 driver-class-name），我的应用程序仍然无法正常工作。

Answer 1

# Allows Hibernate to generate SQL optimized for a particular DBMS
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

需要根据运行的mysql版本修改方言。

MySql 5.5 - org.hibernate.dialect.MySQL55Dialect

MySql 5.7 - org.hibernate.dialect.MySQL57Dialect

MySql 8 - org.hibernate.dialect.MySQL8Dialect

您可以使用此查询检查 MySql 版本

SHOW VARIABLES LIKE "%version%";

并检查 InnoDB 版本

Answer 2

谢谢！！我遇到了同样的问题并使用您的答案解决了它：

1) 首先我用

检查了 MySql 版本

显示变量，例如“%version%”；

2) 然后用右边的修改方言：

MySql 5.5 - org.hibernate.dialect.MySQL55Dialect

MySql 5.7 - org.hibernate.dialect.MySQL57Dialect

MySql 8 - org.hibernate.dialect.MySQL8Dialect

它奏效了！

Answer 3

将这些属性替换到您的 app.prop 文件中。

    # Connection url for the database "netgloo_blog"
spring.datasource.url = jdbc:mysql://localhost:3306/your_db_name?useSSL=false

# Username and password
spring.datasource.username = username
spring.datasource.password = password

# Keep the connection alive if idle for a long time (needed in production)
spring.datasource.testWhileIdle = true
spring.datasource.validationQuery = SELECT 1

# ===============================
# = JPA / HIBERNATE
# ===============================

# Use spring.jpa.properties.* for Hibernate native properties (the prefix is
# stripped before adding them to the entity manager).

# Show or not log for each sql query
spring.jpa.show-sql = true

# Hibernate ddl auto (create, create-drop, update): with "update" the database
# schema will be automatically updated accordingly to java entities found in
# the project
spring.jpa.hibernate.ddl-auto = update

# Naming strategy
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy

# Spring data jpa Auditor <jpa:auditing auditor-aware-ref="customAuditorAware"/>
# Allows Hibernate to generate SQL optimized for a particular DBMS
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

Answer 4

数据源网址应该是：

spring.datasource.url=jdbc:mysql://localhost/database?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC

Answer 5

只需将以下行添加到您的项目属性文件中。

spring.jpa.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

Answer 6

我知道这是一个旧线程。只是更新这个以防其他人面临同样的问题。

如错误消息 - org.hibernate.exception.GenericJDBCException: Unable to open JDBC Connection for DDL execution 中所述，这是一个通用 JDBC 异常，与听起来不同，这并不总是意味着它无法建立连接。

就我而言，我使用不同的数据源和 H2 进行单元测试等。我发现我在 H2 DB 模式创建命令中给出了错误的类路径。如果在 H2 启动时创建表时出现任何查询错误，也会生成同样的错误消息。

对此的最佳解决方案是在调试模式下运行它并找出导致此问题的原因。