C. *_*ith 3 hibernate jpa spring-data-jpa spring-boot
我遇到 org.hibernate.LazyInitializationException：无法延迟初始化角色集合：myapp.myapp.models.Contact.messages，无法初始化代理 - 无会话。我研究过这些类似的问题Hibernate: LazyInitializationException: failed to lazily初始化角色集合。无法初始化代理 - 没有会话以及如何解决 \xe2\x80\x9cfailed to lazily初始化角色\xe2\x80\x9d Hibernate 异常的集合，但它们都没有帮助我的情况。我将 spring 自动配置我的数据源到了没有这个问题的地方，但我添加了另一个数据源连接，然后为每个数据源创建了一个配置文件，现在一切正常，就像以前一样，但我不断收到此消息抛出错误。我不知道该怎么办。任何帮助表示赞赏。
\n\n在添加其他数据库之前，我的属性文件中的数据库信息看起来像这样
\n\n##############DBs##################\nspring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect\nspring.jpa.hibernate.ddl-auto=update\nspring.jpa.database=default\n\n#Myapp DB\nspring.datasource.driverClassName=com.mysql.jdbc.Driver\nspring.datasource.url=jdbc:mysql://localhost:3306/myapp? verifyServerCertificate=false&useSSL=false&requireSSL=false\nspring.datasource.username=myusername\nspring.datasource.password=mypassword\n一切顺利。
\n\n现在一切都是这样设置的。
\n\n属性文件
\n\n##############DBs##################\nspring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect\nspring.jpa.hibernate.ddl-auto=update\nspring.jpa.database=default\n\n#Myapp DB\nspring.datasource.driverClassName=com.mysql.jdbc.Driver\nspring.datasource.url=jdbc:mysql://localhost:3306/myapp? verifyServerCertificate=false&useSSL=false&requireSSL=false\nspring.datasource.username=myusername\nspring.datasource.password=mypassword\n\n#Other DB\nspring.seconddatasource.driverClassName = com.mysql.jdbc.Driver\nspring.seconddatasource.url = jdbc:mysql://localhost:3306/other\nspring.seconddatasource.username=myusername\nspring.seconddatasource.password=mypassword\n###################################\n联系单位：
\n\n@Entity\n@Table(name = "contact")\npublic class Contact {\n\n @Id\n @GeneratedValue(strategy = GenerationType.IDENTITY)\n private long id;\n\n @OneToMany(fetch = FetchType.LAZY, mappedBy = "contact")\n private List<Messages> messages;\n\n public long getId() {\n return this.id;\n }\n\n public void setId(long id) {\n this.id = id;\n }\n\n public List<Messages> getMessages() {\n return this.messages == null ? null : new ArrayList<>(this.messages);\n }\n\n public void setMessages(List<Messages> messages) {\n this.messages = messages;\n }\n\n public void addMessage(Messages message) {\n this.messages.add(message); // this is where the error is being thrown\n }\n}\n消息实体：
\n\n@Entity\n@Table(name = "message")\npublic class Contact {\n\n @Id\n @GeneratedValue(strategy = GenerationType.IDENTITY)\n private long id;\n\n @ManyToOne\n @JoinColumn(name = "contactId", nullable = false)\n private Contact contact;\n\n public long getId() {\n return this.id;\n }\n\n public void setId(long id) {\n this.id = id;\n }\n\n public Contact getContact() {\n return this.contact;\n }\n\n public void setContact(Contact contact) {\n this.contact = contact;\n }\n}\n新的MyAppConfigClass（一旦将其与其他一起放入，错误就开始发生）：
\n\n@ComponentScan\n@Configuration\n@EnableJpaRepositories(\n basePackages = { "myapp.myapp" },\n entityManagerFactoryRef = "myappEntityManagerFactory",\n transactionManagerRef = "myappTransactionManager")\n@EnableTransactionManagement\npublic class MyAppDBConfiguration {\n\n @Autowired private ApplicationContext applicationContext;\n\n @Bean(name = "myappExceptionTranslator")\n public HibernateExceptionTranslator personnelHibernateExceptionTranslator() {\n return new HibernateExceptionTranslator();\n }\n\n @Bean(name = "myappTransactionManager")\n public PlatformTransactionManager personnelTransactionManager() {\n return new JpaTransactionManager(personnelEntityManagerFactory().getObject());\n }\n\n @Bean(name = "myappEntityManagerFactory")\n public LocalContainerEntityManagerFactoryBean personnelEntityManagerFactory() {\n\n HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();\n vendorAdapter.setGenerateDdl(true);\n\n LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();\n factory.setJpaVendorAdapter(vendorAdapter);\n factory.setPackagesToScan("myapp.myapp");\n factory.setDataSource(myappDataSource());\n factory.afterPropertiesSet();\n\n return factory;\n\n }\n\n @Primary\n @Bean(name = "myappDataConfig")\n @ConfigurationProperties("spring.datasource")\n public DataSourceProperties myappProperties() {\n return new DataSourceProperties();\n }\n\n @Bean(name = "myappData", destroyMethod = "")\n public DataSource myappDataSource() {\n DataSourceProperties properties = myappProperties();\n if (null != properties.getJndiName()) {\n JndiDataSourceLookup lookup = new JndiDataSourceLookup();\n DataSource source = lookup.getDataSource(properties.getJndiName());\n excludeMBeanIfNecessary(source, "myappData");\n return source;\n } else {\n return properties.initializeDataSourceBuilder().build();\n }\n }\n\n private void excludeMBeanIfNecessary(Object candidate, String beanName) {\n try {\n MBeanExporter mbeanExporter = this.applicationContext.getBean(MBeanExporter.class);\n if (JmxUtils.isMBean(candidate.getClass())) {\n mbeanExporter.addExcludedBean(beanName);\n }\n } catch (NoSuchBeanDefinitionException ex) {\n // No exporter. Exclusion is unnecessary\n }\n }\n}\n这是OtherConfigClass（几乎完全相同）：
\n\n@ComponentScan\n@Configuration\n@EnableJpaRepositories(\n basePackages = { "myapp.other" },\n entityManagerFactoryRef = "otherEntityManagerFactory",\n transactionManagerRef = "otherTransactionManager")\n@EnableTransactionManagement\npublic class OtherDBConfiguration {\n\n @Autowired private ApplicationContext applicationContext;\n\n @Bean(name = "otherExceptionTranslator")\n public HibernateExceptionTranslator personnelHibernateExceptionTranslator() {\n return new HibernateExceptionTranslator();\n }\n\n @Bean(name = "otherTransactionManager")\n public PlatformTransactionManager personnelTransactionManager() {\n return new JpaTransactionManager(personnelEntityManagerFactory().getObject());\n }\n\n @Bean(name = "otherEntityManagerFactory")\n public LocalContainerEntityManagerFactoryBean personnelEntityManagerFactory() {\n\n HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();\n vendorAdapter.setGenerateDdl(true);\n\n LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();\n factory.setJpaVendorAdapter(vendorAdapter);\n factory.setPackagesToScan("myapp.other");\n factory.setDataSource(otherDataSource());\n factory.afterPropertiesSet();\n\n return factory;\n\n }\n\n @Bean(name = "otherDataConfig")\n @ConfigurationProperties("spring.seconddatasource")\n public DataSourceProperties otherProperties() {\n return new DataSourceProperties();\n }\n\n @Bean(name = "otherData", destroyMethod = "")\n public DataSource textappotherDataSource() {\n DataSourceProperties properties = myappProperties();\n if (null != properties.getJndiName()) {\n JndiDataSourceLookup lookup = new JndiDataSourceLookup();\n DataSource source = lookup.getDataSource(properties.getJndiName());\n excludeMBeanIfNecessary(source, "otherData");\n return source;\n } else {\n return properties.initializeDataSourceBuilder().build();\n }\n }\n\n private void excludeMBeanIfNecessary(Object candidate, String beanName) {\n try {\n MBeanExporter mbeanExporter = this.applicationContext.getBean(MBeanExporter.class);\n if (JmxUtils.isMBean(candidate.getClass())) {\n mbeanExporter.addExcludedBean(beanName);\n }\n } catch (NoSuchBeanDefinitionException ex) {\n // No exporter. Exclusion is unnecessary\n }\n }\n}\n这是应用程序类：
\n\n@EnableAutoConfiguration\n@SpringBootApplication\npublic class MyApplication {\n\n public static void main(String[] args) {\n SpringApplication.run(MyApplication.class, args);\n }\n}\n所以我假设我缺少一些新的配置文件，这些文件是在 AutoConfig 之外完成的。这是我所做的唯一更改，它开始抛出错误。正如我上面所说，数据已正确保存到数据库中，但仍会引发该错误。
\n\n我不知道为什么会出现这种情况，解释会非常有帮助。
\n\n更新：
\n\n联系存储库：
\n\n@Repository\npublic interface ContactRepository extends JpaRepository<Contact, Long> {\n\n}\n消息存储库：
\n\n@Repository\npublic interface MessagesRepository extends JpaRepository<Messages, Long> {\n\n}\n服务等级：
\n\n@Service\npublic void serviceClass(long id) {\n Contact contact = contactRepository.findOne(id);\n Messages msg = new Messages();\n msg.setContact(contact);\n\n // do some work here\n\n Messages savedMessage = messagesRepository.save(msg);\n contact.addMessage(savedMessage);\n contactRepository.save(contact);\n在 application.properties 文件中设置enable_lazy_load_no_trans=true在我的情况下解决了，无需将获取类型从惰性更改为急切。
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