Spring 使用 EntityManager 启动多个数据源

Question

我正在尝试使用 INFOQ 的本教程设置具有多个数据源的 Springboot (v2.0.0.BUILD-SNAPSHOT) 项目

https://www.infoq.com/articles/Multiple-Databases-with-Spring-Boot

但是我需要使用多个 EntityManagers 而不是 JdbcTemplate

这是我到目前为止所拥有的

应用程序属性

spring.primary.url=jdbc:sqlserver://localhost:2433;databaseName=TEST
spring.primary.username=root
spring.primary.password=root
spring.primary.driverClassName=com.microsoft.sqlserver.jdbc.SQLServerDriver

spring.secondary.url=jdbc:oracle:thin:@//localhost:1521/DB
spring.secondary.username=oracle
spring.secondary.password=root
spring.secondary.driverClassName=oracle.jdbc.OracleDriver

应用程序.java

package com.test;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

应用程序配置文件

package com.test.config;
import javax.sql.DataSource;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

@Configuration
public class ApplicationConfiguration {

    @Primary
    @Bean(name = "primaryDB")
    @ConfigurationProperties(prefix = "spring.primary")
    public DataSource postgresDataSource() {
        return  DataSourceBuilder.create().build();
    }

    @Bean(name = "primaryEM")
    public LocalContainerEntityManagerFactoryBean storingEntityManagerFactory(
        EntityManagerFactoryBuilder builder, @Qualifier("primaryDB") DataSource ds) {
        return builder
            .dataSource(ds)
            .packages("com.test.supplier1")
            .persistenceUnit("primaryPU")
            .build();
    }

    @Bean(name = "secondaryDB")
    @ConfigurationProperties(prefix = "spring.secondary")
    public DataSource mysqlDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "secondaryEM")
    public LocalContainerEntityManagerFactoryBean storingEntityManagerFactory(
        EntityManagerFactoryBuilder builder, @Qualifier("secondaryDB") DataSource ds) {
    return builder
            .dataSource(ds)
            .packages("com.test.supplier2")
            .persistenceUnit("secondaryPU")
            .build();
    }

}

通用DAO.java

public abstract class GenericDAO<T extends Serializable> {

    private Class<T> clazz = null;

    @PersistenceContext
    protected EntityManager entityManager;

    public void setClazz(Class<T> clazzToSet) {
        this.clazz = clazzToSet;
    }

    public T findOne(Integer id) {          
        return this.entityManager.find(this.clazz, id);
    }

    public List<T> findAll() {
        return this.entityManager.createQuery("from " + this.clazz.getName()).getResultList();
    }

    @Transactional
    public void save(T entity) {
        this.entityManager.persist(setModifiedAt(entity));
    }
}

PersonDAO.java

@Repository
@PersistenceContext(name = "primaryEM")
public class PersonDAO extends GenericDAO<Person> {
    public PersonDAO() {
        this.setClazz(Person.class);
    }
}

ProductDAO.java

@Repository
@PersistenceContext(name = "secondaryEM")
public class ProductDAO extends GenericDAO<Product> {
    public ProductDAO() {
        this.setClazz(Product.class);
    }
}

测试服务.java

@Service
public class TestService {

    @Autowired
    PersonDAO personDao;

    @Autowired
    ProductDAO productDao;

    // This should write to primary datasource
    public void savePerson(Person person) {
        personDao.save(person);
    }

    // This should write to secondary datasource
    public void saveProduct(Product product) {
        productDao.save(product);
    }

}

问题是它不起作用。 当我尝试保留“产品”（辅助 ds）时，它还尝试保留到 @Primary 数据源。

我怎样才能做到类似于文章中的 JdbcTemplate 示例？

我究竟做错了什么 ？

谢谢 ！

更新（尝试@Deepak 解决方案）

试试下面的

@Repository
public class PersonDAO extends GenericDAO<Person> {
    @Autowired
    public PersonDAO(@Qualifier("primaryEM") EntityManager entityManager) {
        this.entityManager = entityManager;
        this.setClazz(Person.class);
    }
}

产品DAO

@Repository
public class ProductDAO extends GenericDAO<Product> {
    @Autowired
    public ProductDAO(@Qualifier("secondaryEM") EntityManager entityManager) {
        this.entityManager = entityManager;
        this.setClazz(Product.class);
    }
}

同时从 GenericDAO 中删除 @PersistenceContext 注释

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::  (v2.0.0.BUILD-SNAPSHOT)

com.test.Application                     : Starting Application on...   
com.test.Application                     : No active profile set, falling back to default profiles: default 
ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@69b2283a: startup date [Thu Apr 20 15:28:59 BRT 2017]; root of context hierarchy  
.s.d.r.c.RepositoryConfigurationDelegate : Multiple Spring Data modules found, entering strict repository configuration mode!   
.s.d.r.c.RepositoryConfigurationDelegate : Multiple Spring Data modules found, entering strict repository configuration mode!   
f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring  
o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8081 (http) 
o.apache.catalina.core.StandardService   : Starting service Tomcat  
org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.12    
o.a.c.c.C.[Tomcat].[localhost].[/    : Initializing Spring embedded WebApplicationContext
o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 4001 ms  

o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]  
o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]   
o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]    
o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]  
o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]  

j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'primaryPU' 
o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [  name: primaryPU ...]    
org.hibernate.Version                    : HHH000412: Hibernate Core {5.2.9.Final}  
org.hibernate.cfg.Environment            : HHH000206: hibernate.properties not found    
o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.0.1.Final} 
org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.SQLServer2012Dialect 
j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'primaryPU'    

j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'secondaryPU'   
o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [  name: secondaryPU   ...]
org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.SQLServer2012Dialect 
j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'secondaryPU'

s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@69b2283a: startup date [Thu Apr 20 15:28:59 BRT 2017]; root of context hierarchy  
s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)    
s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)  
o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/** onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/** onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup    
s.a.ScheduledAnnotationBeanPostProcessor : No TaskScheduler/ScheduledExecutorService bean found for scheduled processing    
o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8081 (http)   
io.test.Application                      : Started Application in 76.21 seconds (JVM running for 77.544)    

org.hibernate.SQL                        : select next value for SEQ_TDAI_ID    
o.h.engine.jdbc.spi.SqlExceptionHelper   : SQL Error: 923, SQLState: 42000  
o.h.engine.jdbc.spi.SqlExceptionHelper   : ORA-00923: FROM keyword not found where expected 
--> ERROR

似乎它正在使用@Primary 数据源方言（在本例中为“ SQLServer2012Dialect ”）构建两个实体。

次要 EntityManager 应该是“ Oracle12cDialect ”。

更新（解决方案）

似乎连接没问题，唯一的问题是错误的方言（似乎它默认为@Primary DataSource 方言），所以解决方案是在 EntityManagerFactory 上强制它，这是我的快速修复：

1) 向application.properties文件添加正确的方言

spring.primary.hibernate.dialect=org.hibernate.dialect.SQLServer2012Dialect
spring.secondary.hibernate.dialect=org.hibernate.dialect.Oracle12cDialect

2）将application.properties方言值导入ApplicationConfiguration.java

@Value("${spring.primary.hibernate.dialect}")
private String dialect;

3) 强制它进入 EntityManagerFactory

@Bean(name = "primaryEM")
public LocalContainerEntityManagerFactoryBean storingEntityManagerFactory(
    EntityManagerFactoryBuilder builder, @Qualifier("primaryDB") DataSource ds) {

    Properties properties = new Properties();
    properties.setProperty("hibernate.dialect", dialect);

    LocalContainerEntityManagerFactoryBean emf = builder
        .dataSource(ds)
        .packages("com.test.supplier1")
        .persistenceUnit("primaryPU")
        .build();

    emf.setJpaProperties(properties);

    return emf;
}

现在它起作用了。

有没有更优雅的方法来做到这一点？

Answer 1

试试下面的

@Repository
public class PersonDAO extends GenericDAO<Person> {
    @Autowired
    public PersonDAO(@Qualifier("primaryEM") EntityManager entityManager) {
        this.entityManager = entityManager;
        this.setClazz(Person.class);
    }
}

产品DAO

@Repository
public class ProductDAO extends GenericDAO<Product> {
    @Autowired
    public ProductDAO(@Qualifier("secondaryEM") EntityManager entityManager) {
        this.entityManager = entityManager;
        this.setClazz(Product.class);
    }
}

同时从 GenericDAO 中删除 @PersistenceContext 注释

Answer 2

我认为您应该将 "@PersistenceContext(name = "secondaryEM")" 更改为 "@PersistenceContext(unitName = "secondaryEM")" 以指定持久性单元。

Answer 3

这对我有用：

应用程序属性

app.hibernate.primary.hibernate.dialect=org.hibernate.dialect.SQLServer2012Dialect
app.hibernate.secondary.hibernate.dialect=org.hibernate.dialect.Oracle12cDialect

您可以将更多的 hibernate 属性添加到主服务器，添加到辅助服务器，例如 hibernate.hbm2ddl.auto、hibernate.show_sql 等。

应用程序配置文件

@Bean("primaryhibernateproperties")
@ConfigurationProperties("app.hibernate.primary")
public Properties primaryHibernateProperties() {
    return new Properties();
}

@Bean(name = "primaryEM")
public LocalContainerEntityManagerFactoryBean storingEntityManagerFactory(
    EntityManagerFactoryBuilder builder, @Qualifier("primaryDB") DataSource ds) {

    LocalContainerEntityManagerFactoryBean emf = builder
        .dataSource(ds)
        .packages("com.test.supplier1")
        .persistenceUnit("primaryPU")
        .build();

    emf.setJpaProperties(primaryHibernateProperties());

    return emf;
}
// same with secondary

通用DAO

public abstract class GenericDAO<T extends Serializable> {

    private Class<T> clazz;
    private EntityManager entityManger;

    public GenericDAO(EntityManager entityManger, Class<T> clazz) {
        this.entityManger = entityManager;
        this.clazz = clazz;
    }
    // other codes
}

PersonDAO

@Repository
public class PersonDAO extends GenericDAO<Person> {
    @Autowired
    public PersonDAO(@Qualifier("primaryEM") EntityManager entityManager) {
        super(entityManager, Person.class);
    }
}

产品DAO

@Repository
public class ProductDAO extends GenericDAO<Product> {
    @Autowired
    public ProductDAO(@Qualifier("secondaryEM") EntityManager entityManager) {
        super(entityManager, Product.class);
    }
}