如何在不依赖数据库的情况下启动 spring-boot 应用程序？

Question

我正在为我的应用程序使用“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，当我尝试在没有数据库启动的情况下启动我的 Spring Boot 应用程序时，它给出了以下异常。

我研究了很多，发现这个异常与hibernate.temp.use_jdbc_metadata_defaults属性有关。

我尝试在 spring boot 的“application.yml”中设置它，但在运行时没有反映这个属性的值。

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

Answer 1

这确实是一个难以破解的难题。

经过大量的研究和实际调试 spring-boot、spring、hibernate、tomcat 池等来完成它。

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

1. 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。
2. 应用程序将在数据库启动时即时获取连接，这意味着无需重新启动 Web 服务器或重新部署应用程序。
3. 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

Answer 2

我在这里回答并将关闭您交叉发布的问题

JPA实现（休眠）的任何“本地”属性还可以用设置spring.jpa.properties前缀这里解释

我没有进一步研究这里的实际问题，但要回答这个特定问题，您可以按如下方式设置该休眠键

spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults

Answer 3

单独添加这个对我有用：

spring.jpa.properties.hibernate.dialect: org.hibernate.dialect.Oracle10gDialect

只需用您的数据库方言替换最后一部分。

Answer 4

该解决方案对我来说非常有用。 谢谢我使用的文件“application.properties”包括以下几行：

    app.sqlhost=192.168.10.11
    app.sqlport=3306
    app.sqldatabase=logs

    spring.main.web-application-type=none

    # Datasource
    spring.datasource.url=jdbc:mysql://${app.sqlhost}:${app.sqlport}/${app.sqldatabase}
    spring.datasource.username=user
    spring.datasource.password=password
    spring.datasource.driver-class-name=com.mysql.jdbc.Driver
    spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
    spring.jpa.properties.hibernate.hbm2dll.auto = none
    spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults = false

    spring.datasource.continue-on-error=true
    spring.datasource.initialization-mode=never

    spring.datasource.hikari.connection-timeout=5000
    spring.datasource.hikari.idle-timeout=600000
    spring.datasource.hikari.max-lifetime=1800000
    spring.datasource.hikari.initialization-fail-timeout= -1

    spring.jpa.hibernate.use-new-id-generator-mappings=true
    spring.jpa.hibernate.ddl-auto=none

    spring.jpa.show-sql=true

    spring.output.ansi.enabled=always

但是，您不能在类级别使用 @Transactional 注释

@Service
//@Transactional  //do not use to touch the Repository
@EnableAsync
@Scope( proxyMode = ScopedProxyMode.TARGET_CLASS )
public class LogService {
.... }

@Async
@Transactional  // you can use at function level
public void deleteLogs(){
    logRepository.deleteAllBy ...
}

Answer 5

添加以下配置应该可以工作：

spring.jpa.database-platform: org.hibernate.dialect.MySQL5Dialect