我的应用程序使用“Spring-boot + Hibernate4 + mysql”。作为其中的一部分，我有一个要求，即使数据库关闭，我的 sprint-boot 应用程序也应该能够启动。目前，当我尝试在数据库未启动的情况下启动我的 Spring Boot 应用程序时，它会给出以下异常。
我研究了很多，发现这个异常与hibernate.temp.use_jdbc_metadata_defaults财产。
我尝试在 Spring Boot 的“application.yml”中设置此属性，但此属性的值在运行时并未反映。
异常堆栈跟踪：
2014-05-25 04:09:43.193 INFO 59755 --- [ main] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {4.0.4.Final}
2014-05-25 04:09:43.250 WARN 59755 --- [ main] o.h.e.jdbc.internal.JdbcServicesImpl : 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.
2014-05-25 04:09:43.263 INFO 59755 --- [ main] o.apache.catalina.core.StandardService : Stopping service Tomcat
Error starting ApplicationContext. To display the auto-configuration report enabled debug logging (start with --debug)
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1553)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:973)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:750)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:120)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:648)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:311)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:909)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:898)
at admin.Application.main(Application.java:36)
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:104)
at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:71)
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:205)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:89)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:206)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:178)
at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:850)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:843)
at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.withTccl(ClassLoaderServiceImpl.java:399)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:842)
at org.hibernate.jpa.HibernatePersistenceProvider.createContainerEntityManagerFactory(HibernatePersistenceProvider.java:150)
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:336)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:318)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1612)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1549)
... 15 more
应用程序.yml：
spring:
jpa:
show-sql: true
hibernate:
ddl-auto: none
naming_strategy: org.hibernate.cfg.DefaultNamingStrategy
temp:
use_jdbc_metadata_defaults: false
这确实是一个很难破解的难题。
经过大量的研究并实际调试 spring-boot、spring、hibernate、tomcat pool 等才能完成。
我确实认为这将为尝试实现此类要求的人们节省大量时间。
以下是实现以下要求所需的设置
- 即使数据库关闭或没有数据库，Spring Boot 应用程序也能正常启动。
- 当数据库启动时，应用程序将即时获取连接，这意味着无需重新启动 Web 服务器或重新部署应用程序。
- 如果数据库从运行状态下降并再次出现，则无需启动 tomcat 或重新部署应用程序。
应用程序.yml：
spring:
datasource:
driverClassName: com.mysql.jdbc.Driver
url: jdbc:mysql://localhost:3306/schema
username: root
password: root
continueOnError: true
initialize: false
initialSize: 0
timeBetweenEvictionRunsMillis: 5000
minEvictableIdleTimeMillis: 5000
minIdle: 0
jpa:
show-sql: true
hibernate:
ddl-auto: none
naming_strategy: org.hibernate.cfg.DefaultNamingStrategy
properties:
hibernate:
dialect: org.hibernate.dialect.MySQL5Dialect
hbm2ddl:
auto: none
temp:
use_jdbc_metadata_defaults: false
本文内容由网友自发贡献，版权归原作者所有，本站不承担相应法律责任。如您发现有涉嫌抄袭侵权的内容，请联系:hwhale#tublm.com(使用前将#替换为@)
