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由于项目需要，最近研究了一下基于spring Boot与Spring Data JPA的多数据源配置问题。以下是传统的单数据源配置代码。这里使用的是Spring的Annotation在代码内部直接配置的方式，没有使用任何XML文件。
@Configuration
@EnableJpaRepositories(basePackages = "org.lyndon.repository")
@EnableTransactionManagement
@PropertySource("classpath:application.properties")
public class JpaConfig {
private static final String DATABASE_DRIVER = "db.driver";
private static final String DATABASE_URL = "db.url";
private static final String DATABASE_USER = "db.user";
private static final String DATABASE_PASSWORD = "db.password";
private static final String PACKAGES_TO_SCAN = "packages.to.scan";
private static final String HIBERNATE_DIALECT = "hibernate.dialect";
private static final String HIBERNATE_SHOW_SQL = "hibernate.show.sql";
@Resource
private Environment env;
@Bean
public DataSource dataSource() {
DruidDataSource source = new DruidDataSource();
source.setDriverClassName(env.getRequiredProperty(DATABASE_DRIVER));
source.setUrl(env.getRequiredProperty(DATABASE_URL));
source.setUsername(env.getRequiredProperty(DATABASE_USER));
source.setPassword(env.getRequiredProperty(DATABASE_PASSWORD));
return source;
}
@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
factory.setDataSource(dataSource());
factory.setPersistenceProviderClass(HibernatePersistenceProvider.class);
factory.setPackagesToScan(env.getRequiredProperty(PACKAGES_TO_SCAN));
factory.setJpaProperties(hibernateProperties());
factory.afterPropertiesSet();
return factory;
}
@Bean
public PlatformTransactionManager transactionManager() {
JpaTransactionManager manager = new JpaTransactionManager();
manager.setEntityManagerFactory(entityManagerFactory().getObject());
return manager;
}
@Bean
public HibernateExceptionTranslator hibernateExceptionTranslator() {
return new HibernateExceptionTranslator();
}
private Properties hibernateProperties() {
Properties properties = new Properties();
properties.put(HIBERNATE_DIALECT, env.getRequiredProperty(HIBERNATE_DIALECT));
properties.put(HIBERNATE_SHOW_SQL, env.getRequiredProperty(HIBERNATE_SHOW_SQL));
return properties;
}
}
</div>
但是这一配置是不能简单地扩展到多数据源配置的，因为Spring Boot默认会为开发人员做很多工作，而这些工作与多数据源的配置相冲突，因此需要修改原来的配置内容。网上有很多讲解多数据源配置的文章，但是这些文章大多使用的是XML配置的方式，而且没有使用Spring Boot等比较新的Spring框架技术（比如很多人使用实现AbstractRoutingDataSource这一Spring提供的抽象类的方式，还需要切面的支持，无疑是相当繁琐的），已经不适用于在最新的工程项目中使用了，因为最新的Spring框架可以为我们完成很多事情，我们只需要去适应新的方法即可。为此，我通过研究Spring的官方文档和不断调试，实现了新的多数据源配置的方法，在此贴出，仅供参考。
首先，Spring的JPA是直接支持多数据源配置的，因此我们可以在配置文件或者代码中直接配置多个数据源。由于多数据源配置可能会共享一些配置信息，因此使用继承体系实现这种配置是最合适的。在例子中，我的ORM框架使用的是hibernate，而与Hibernate相关的配置信息我都放在了配置基类BaseJpaConfg中，代码如下。
@Configuration
@EnableTransactionManagement
@PropertySource("classpath:application.properties")
public class BaseJpaConfig {
private static final String HIBERNATE_DIALECT = "hibernate.dialect";
private static final String HIBERNATE_SHOW_SQL = "hibernate.show.sql";
@Resource
protected Environment env;
@Bean
public HibernateExceptionTranslator hibernateExceptionTranslator() {
return new HibernateExceptionTranslator();
}
protected Properties hibernateProperties() {
Properties properties = new Properties();
properties.put(HIBERNATE_DIALECT, env.getRequiredProperty(HIBERNATE_DIALECT));
properties.put(HIBERNATE_SHOW_SQL, env.getRequiredProperty(HIBERNATE_SHOW_SQL));
return properties;
}
}
</div>
该类提供Hibernate相关信息。它有两个子类，分别是SpringJpaConfig以及MysqlJpaConfig，分别配置了两个数据源，连接到两个不同的数据库Schema，代码如下。
@Configuration
@EnableJpaRepositories(basePackages = {"org.lyndon.repository1"}, entityManagerFactoryRef = "springEntityManagerFactory",
transactionManagerRef = "springTransactionManager")
public class SpringJpaConfig extends BaseJpaConfig {
private static final String DATABASE_DRIVER = "db.driver";
private static final String DATABASE_URL = "db.url";
private static final String DATABASE_USER = "db.user";
private static final String DATABASE_PASSWORD = "db.password";
private static final String PACKAGES_TO_SCAN = "packages.to.scan";
@Bean
@ConfigurationProperties(prefix = "datasource.primary")
public DataSource dataSource() {
DruidDataSource source = new DruidDataSource();
source.setDriverClassName(env.getRequiredProperty(DATABASE_DRIVER));
source.setUrl(env.getRequiredProperty(DATABASE_URL));
source.setUsername(env.getRequiredProperty(DATABASE_USER));
source.setPassword(env.getRequiredProperty(DATABASE_PASSWORD));
return source;
}
@Bean(name = "springEntityManagerFactory")
public LocalContainerEntityManagerFactoryBean springEntityManagerFactory() {
LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
factory.setDataSource(dataSource());
factory.setPersistenceProviderClass(HibernatePersistenceProvider.class);
factory.setPackagesToScan(env.getRequiredProperty(PACKAGES_TO_SCAN).split(","));
factory.setJpaProperties(hibernateProperties());
factory.afterPropertiesSet();
return factory;
}
@Bean(name = "springTransactionManager")
@Primary
public PlatformTransactionManager transactionManager() {
JpaTransactionManager manager = new JpaTransactionManager();
manager.setEntityManagerFactory(springEntityManagerFactory().getObject());
return manager;
}
}
</div>
@Configuration
@EnableJpaRepositories(basePackages = {"org.lyndon.repository2"}, entityManagerFactoryRef = "mysqlEntityManagerFactory",
transactionManagerRef = "mysqlTransactionManager")
public class MysqlJpaConfig extends BaseJpaConfig {
private static final String DATABASE_DRIVER = "db.driver";
private static final String DATABASE_URL = "db.url2";
private static final String DATABASE_USER = "db.user";
private static final String DATABASE_PASSWORD = "db.password";
private static final String PACKAGES_TO_SCAN = "packages.to.scan2";
@Bean
@ConfigurationProperties(prefix = "datasource.secondary")
public DataSource dataSource2() {
DruidDataSource source = new DruidDataSource();
source.setDriverClassName(env.getRequiredProperty(DATABASE_DRIVER));
source.setUrl(env.getRequiredProperty(DATABASE_URL));
source.setUsername(env.getRequiredProperty(DATABASE_USER));
source.setPassword(env.getRequiredProperty(DATABASE_PASSWORD));
return source;
}
@Bean(name = "mysqlEntityManagerFactory")
public LocalContainerEntityManagerFactoryBean mysqlEntityManagerFactory() {
LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
factory.setDataSource(dataSource2());
factory.setPersistenceProviderClass(HibernatePersistenceProvider.class);
factory.setPackagesToScan(env