在spring boot中连接到多个数据库

Posted 2023-02-26

【中文标题】在spring boot中连接到多个数据库

【英文标题】：Connecting to multiple database in spring boot

【发布时间】：2019-01-13 15:03:03

【问题描述】：

我需要在我的项目中连接到两个数据库。所以我创建了两个配置文件。

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories( basePackages = "com.virat.webservices.datastore.v1.Repo"  )
@EntityScan("com.virat.webservices.datastore.v1.Model")
public class V1DBConfig 

@Primary
@Bean( name = "dataSource" )
@ConfigurationProperties( prefix = "v1.datasource" )
public DataSource dataSource()

    return DataSourceBuilder.create().build();


@Primary
@Bean( name = "entityManagerFactory" )
public LocalContainerEntityManagerFactoryBean entityManagerFactory( EntityManagerFactoryBuilder builder,
        @Qualifier( "dataSource" ) DataSource dataSource )

    return builder.dataSource(dataSource).packages("com.virat.webservices.datastore.v1.Model")
            .persistenceUnit("db1").build();


@Primary
@Bean( name = "transactionManager" )
public PlatformTransactionManager transactionManager(
        @Qualifier( "entityManagerFactory" ) EntityManagerFactory entityManagerFactory )

    return new JpaTransactionManager(entityManagerFactory);

和

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories( entityManagerFactoryRef = "v2EntityManagerFactory", transactionManagerRef = "v2TransactionManager",    basePackages = 
    "com.virat.datastore.repository"  )
@EntityScan( "com.virat.datastore.model" )
public class V2DBConfig 

@Bean( name = "v2DataSource" )
@ConfigurationProperties( prefix = "spring.datasource" )
public DataSource dataSource()

    return DataSourceBuilder.create().build();


@Bean( name = "v2EntityManagerFactory" )
public LocalContainerEntityManagerFactoryBean barEntityManagerFactory( EntityManagerFactoryBuilder builder,
        @Qualifier( "v2DataSource" ) DataSource dataSource )

    return builder.dataSource(dataSource).packages("com.virat.model")
            .persistenceUnit("db2").build();


@Bean( name = "v2TransactionManager" )
public PlatformTransactionManager barTransactionManager(
        @Qualifier( "v2EntityManagerFactory" ) EntityManagerFactory barEntityManagerFactory )

    return new JpaTransactionManager(barEntityManagerFactory);

我将我的application.properties 文件配置为，

spring.datasource.type=com.zaxxer.hikari.HikariDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/db2?      useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=fal.   se&serverTimezone=UTC&useSSL=false
spring.datasource.username=root
spring.datasource.password=
#spring.datasource.pool.size=20
v1.datasource.driver-class-name=com.mysql.jdbc.Driver
v1.datasource.url=jdbc:mysql://localhost:3306/db1?     useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=fal.   se&serverTimezone=UTC&useSSL=false
v1.datasource.username=root
v1.datasource.password=
#v1.datasource.pool.size=20
spring.jpa.properties.hibernate.id.new_generator_mappings=false
v1.jpa.properties.hibernate.id.new_generator_mappings=false
#spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true

但是当我运行应用程序时，抛出了以下异常。

***************************
APPLICATION FAILED TO START
***************************

Description:

Field entityManager in com.highpeak.tlp.webservices.services.impl.TaskServiceImpl required a single bean, but 2 were found:
    - org.springframework.orm.jpa.SharedEntityManagerCreator#0: defined by method 'createSharedEntityManager' in null
    - org.springframework.orm.jpa.SharedEntityManagerCreator#1: defined by method 'createSharedEntityManager' in null


Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed

 org.springframework.boot.diagnostics.LoggingFailureAnalysisReporter org.springframework.boot.diagnostics.LoggingFailureAnalysisReporter:42 - 

***************************
APPLICATION FAILED TO START
***************************

Description:

Field entityManager in com.highpeak.tlp.webservices.services.impl.TaskServiceImpl required a single bean, but 2 were found:
    - org.springframework.orm.jpa.SharedEntityManagerCreator#0: defined by method 'createSharedEntityManager' in null
    - org.springframework.orm.jpa.SharedEntityManagerCreator#1: defined by method 'createSharedEntityManager' in null


Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed

Disconnected from the target VM, address: '127.0.0.1:56875', transport: 'socket'

Process finished with exit code 1

我无法确定是什么错误。我有两个模块。一个数据库的repository 和entity 类在一个模块中，而另一个数据库的类在另一个模块中。这会导致问题吗？

编辑

我的TaskServiceImpl.java

package com.virat.webservices.services.impl;


@Service
public class TaskServiceImpl implements TaskService 

    private static final Logger LOGGER = LoggerFactory.getLogger(TaskServiceImpl.class);

    @Autowired
    @PersistenceContext(unitName = "v2EntityManagerFactory")
    private EntityManager entityManager;

    @Value( "$file.base.path" )
    private String basePath;

    @Value( "$application.domain" )
    private String applicationDomain;

    @Value( "$application.protocol" )
    private String applicationProtocol;

    @Value( "$server.port" )
    private String serverPort;

    @Override
    @SuppressWarnings( "unchecked" )
    @Transactional( rollbackOn = DataException.class )
    public Integer doSomething( SomeObject someObject,
            UserAccessDetails userAccessDetails ) throws DataException
    
        try
        
            // Do input validations
            if( NullEmptyUtils.isNull(userAccessDetails) || NullEmptyUtils.isNull(someObject) )
            

                throw new DataException(GeneralConstants.EXCEPTION, GeneralConstants.NULL_INPUT_ERROR,
                        HttpStatus.BAD_REQUEST);
            

            // Creates a native mysql query based on the contents of lawyerDiscoveryParamsBean
            /* Should be replaced with criteria API */
            String generatedQuery = DynamicQueryGenerator.getDynamicQuery(someObject, owner);
            LOGGER.info("Generated query: ", generatedQuery);
            Query executableQuery = entityManager.createNativeQuery(generatedQuery, UserModel.class);

            List<UserModel> userModels = executableQuery.getResultList();

            if( userModels.isEmpty() )
            

                return 0;
            

            return 1;

        
        catch( DataException e )
        
            LOGGER.error(GeneralConstants.ERROR, e);
            throw e;
        
        catch( Exception e )
        
            LOGGER.error(GeneralConstants.ERROR, e);
            throw new DataException(GeneralConstants.EXCEPTION, GeneralConstants.SOMETHING_WENT_WRONG,
                    HttpStatus.INTERNAL_SERVER_ERROR);
        
    

【问题讨论】：

能否请您加入TaskServiceImpl？

@Dan 添加了课程

你看过这个问题的答案了吗：***.com/questions/45663025/…

这是另一个值得检查的好资源：roufid.com/spring-boot-multiple-databases-configuration

【参考方案1】：

在您的TaskServiceImpl 中确保您正确注释了 persistenceContext。

例如：

@PersistenceContext(unitName = "entityManagerFactory")
private EntityManager em;

【讨论】：

我采用了同样的方法。但是，现在例外说，Bean named 'v2DataSource' is expected to be of type 'javax.persistence.EntityManagerFactory' but was actually of type 'org.apache.tomcat.jdbc.pool.DataSource'

试过了。它给出了问题中发布的原始异常

删除 @Autowired 之前的 @PersistenceContext 注释

谢谢@Dan。我犯了答案中指定的一些错误。我错了，我都没有正确命名。

【参考方案2】：

在V1DBConfig.java中，注解@EnableJpaRepository其实应该是这样的，

@EnableJpaRepositories( entityManagerFactoryRef = "entityManagerFactory", transactionManagerRef = "transactionManager", basePackages = 
        "com.virat.webservices.datastore.v1.Repo"  )

您已经在V2DBConfig.java 类中完成了配置（查看@EnableJpaRepository 注释）。在V1DBConfig.java 中做同样的事情。

然后，在您的TaskServiceImpl.java 中，提供PersistenceContext，由@Dan 回答。我希望这会有所帮助。