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前言

隨著業務量發展，我們通常會進行數據庫拆分或是引入其他數據庫，從而我們需要配置多個數據源，如：user一個庫，business一個庫。那么接下來我們就要考慮怎么去在spring boot中實現多個數據源的配置。

實現

• 建表
• 首先是建表語句，我們要建立兩個數據庫，并各庫內新建一張表
• user表

mysql> use `user`； mysql> select * from `user`; +----+-------+----------+ | id | name ?| password | +----+-------+----------+ | ?1 | 用戶A | ****** ? | +----+-------+----------+ 1 row in set

• business表

mysql> use `business`； mysql> select * from `business`; +----+-------+-------------+ | id | name ?| description | +----+-------+-------------+ | ?1 | 業務A | 業務A描述 ? | +----+-------+-------------+ 1 row in set

• 接下來我們通過代碼實現對兩個庫內的多張表進行查詢。
• 配置
• 首先，創建一個Spring配置類，定義兩個DataSource用來讀取application.yml中的不同配置。本文中，我們user做為主數據源，主數據源配置為spring.datasource.user開頭的配置，business數據源配置為spring.datasource.business開頭的配置。

@Configuration public class DataSourceConfig {@Primary@Bean(name = "userDataSource")@Qualifier("userDataSource")@ConfigurationProperties(prefix = "spring.datasource.user")public DataSource userDataSource() {return DataSourceBuilder.create().build();}@Bean(name = "businessDataSource")@Qualifier("businessDataSource")@ConfigurationProperties(prefix = "spring.datasource.business")public DataSource businessDataSource() {return DataSourceBuilder.create().build();} }

• 對應的配置文件application.yml如下：

spring:datasource:user:driver-class-name: com.mysql.jdbc.Driverjdbc-url: jdbc:mysql://localhost:3306/userusername: rootpassword: 123456business:driver-class-name: com.mysql.jdbc.Driverjdbc-url: jdbc:mysql://localhost:3306/businessusername: rootpassword: 123456

• 接下來我們對各數據源進行jpa的配置
• 主數據源User

@Configuration @EnableTransactionManagement @EnableJpaRepositories(entityManagerFactoryRef = "entityManagerFactoryUser",transactionManagerRef = "transactionManagerUser",//設置Repository所在位置basePackages = {"com.ppc.spring.example.jpamultidatasource.repository.user"}) public class UserConfig {@Autowired@Qualifier("userDataSource")private DataSource userDataSource;@Autowiredprivate JpaProperties jpaProperties;@Autowiredprivate HibernateProperties hibernateProperties;@Primary@Bean(name = "entityManagerUser")public EntityManager entityManager(EntityManagerFactoryBuilder builder) {return entityManagerFactoryUser(builder).getObject().createEntityManager();}@Primary@Bean(name = "entityManagerFactoryUser")public LocalContainerEntityManagerFactoryBean entityManagerFactoryUser(EntityManagerFactoryBuilder builder) {return builder.dataSource(userDataSource)//設置entity所在位置.packages("com.ppc.spring.example.jpamultidatasource.entity.user").persistenceUnit("userPersistenceUnit").properties(getVendorProperties()).build();}private Map<String, Object> getVendorProperties() {return hibernateProperties.determineHibernateProperties(jpaProperties.getProperties(), new HibernateSettings());}@Primary@Bean(name = "transactionManagerUser")public PlatformTransactionManager transactionManagerUser(EntityManagerFactoryBuilder builder) {return new JpaTransactionManager(entityManagerFactoryUser(builder).getObject());} }

• 其他數據源business

@Configuration @EnableTransactionManagement @EnableJpaRepositories(entityManagerFactoryRef = "entityManagerFactoryBusiness",transactionManagerRef = "transactionManagerBusiness",//設置repository所在位置basePackages = {"com.ppc.spring.example.jpamultidatasource.repository.business"}) public class BusinessConfig {@Autowired@Qualifier("businessDataSource")private DataSource businessDataSource;@Autowiredprivate JpaProperties jpaProperties;@Autowiredprivate HibernateProperties hibernateProperties;@Bean(name = "entityManagerBusiness")public EntityManager entityManager(EntityManagerFactoryBuilder builder) {return entityManagerFactoryBusiness(builder).getObject().createEntityManager();}@Bean(name = "entityManagerFactoryBusiness")public LocalContainerEntityManagerFactoryBean entityManagerFactoryBusiness(EntityManagerFactoryBuilder builder) {return builder.dataSource(businessDataSource).properties(getVendorProperties())//設置實體類所在位置.packages("com.ppc.spring.example.jpamultidatasource.entity.business").persistenceUnit("businessPersistenceUnit").build();}private Map<String, Object> getVendorProperties() {return hibernateProperties.determineHibernateProperties(jpaProperties.getProperties(), new HibernateSettings());}@Bean(name = "transactionManagerBusiness")PlatformTransactionManager transactionManagerBusiness(EntityManagerFactoryBuilder builder) {return new JpaTransactionManager(entityManagerFactoryBusiness(builder).getObject());} }

• 配置中需要注意以下幾點：
• Spring Boot 1.5.x

private Map<String, String> getVendorProperties() {return jpaProperties.getHibernateProperties(userDataSource); }

• Spring Boot 2.0.x

private Map<String, Object> getVendorProperties() {return jpaProperties.getHibernateProperties(new HibernateSettings()); }

• Spring Boot 2.1.0參見上文代碼，引進了HibernateProperties。同時，在Spring Boot 2.1.0中默認的mysql-connector-java版本為8.0.13，連接低版本mysql配置上比較繁瑣，建議在配置文件中手動指定相應版本，如本文中指定5.1.46這個版本。

runtimeOnly('mysql:mysql-connector-java:5.1.46')

• repository、entity的所在位置，要和實際保存的位置一致。
• ?
• 主數據源的一些配置需要添加@Primary作為spring默認的首選項，其他數據源無需添加該注解。
• ?
• 通過查看相關源碼我們看到Spring Boot中JpaProperties的代碼一直在調整，這里我們將properties相關代碼單獨提取出作為一個單獨的方法getVendorProperties展示版本間的區別。其中：
• 查詢
• 完成了所有的配置，接下來我們就可以開始寫個簡單代碼驗證我們配置了

@RestController @SpringBootApplication public class JpaMultiDatasourceApplication {@AutowiredUserRepository userRepository;@AutowiredBusinessRepository businessRepository;public static void main(String[] args) {SpringApplication.run(JpaMultiDatasourceApplication.class, args);}@GetMapping("/user/{id}")public User getUser(@PathVariable Long id) {return userRepository.findById(id).orElse(null);}@GetMapping("/business/{id}")public Business getBusiness(@PathVariable Long id) {return businessRepository.findById(id).orElse(null);} }

• 我們對外暴露了兩個接口，分別訪問user表、business表確認可以正常獲取數據。查詢結果如下：

請求：http://localhost:8080/user/1 結果：{"id":1,"name":"用戶A","password":"******"} 請求：http://localhost:8080/business/1 結果：{"id":1,"name":"業務A","description":"業務A描述"}

• 就此，我們雙數據源的配置和驗證工作就完成了。

轉載于:https://my.oschina.net/u/3959468/blog/2875232

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