SpringBoot一个项目同时连接操作两台数据库已成功-Java-E先生的博客

本文章使用的是持久化框架为JPA，所以数据源也是基于JPA。采用的是SpringBoot2+SpringDataJPA+MySQL+双数据源！

一、双数据源的适用场景：

1、主从库分离（数据库读写分离）

2、数据迁移

3、系统版本升级，数据库升级到另外一款

二、application.yml中配置

spring:

jpa:

hibernate:

ddl-auto: create

naming:

physical-strategy: org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy

implicit-strategy: org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy

open-in-view: true

show-sql: true

generate-ddl: true

datasource: #database

primary: # 3.0 Datasource

jdbc-url: jdbc:mysql://127.0.0.1:3306/gtu?characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai

username: root

password: 123456

secondary: # 2.0 Datasource

jdbc-url: jdbc:mysql://127.0.0.1:3306/gtu-not-completed?characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai

username: root

password: 123456

注：配置文件中需要指定两个数据源，这里在配置的时候是没有自动提示的，因为这是我们自定义的，需要在程序中动态读取。

三、读取application.yml配置的两个数据源，并将其注入到Spring的IOC容器中

@Configuration

public class DataSourceConfig {

@Bean(name = "primaryDataSource")

@Qualifier("primaryDataSource")

@Primary

@ConfigurationProperties(prefix = "spring.datasource.primary")

public DataSource primaryDataSource() {

return DataSourceBuilder.create().build();

}

@Bean(name = "secondaryDataSource")

@Qualifier("secondaryDataSource")

@ConfigurationProperties(prefix = "spring.datasource.secondary")

public DataSource secondaryDataSource() {

return DataSourceBuilder.create().build();

}

}

注解解释：

Configuration：SpringBoot启动将该类作为配置类，同配置文件一起加载

Bean：将该实体注入到IOC容器中

Qualifier：指定数据源名称，与Bean中的name属性原理相同，主要是为了确保注入成功

Primary：指定主数据源

ConfigurationProperties：将配置文件中的数据源读取进到方法中，进行build

四、以类的方式配置两个数据源

（1）主数据源（对应DataSourceConfig类中的primaryDataSource）

@Configuration

@EnableTransactionManagement

@EnableJpaRepositories(

entityManagerFactoryRef = "entityManagerFactoryPrimary",

transactionManagerRef = "transactionManagerPrimary",

basePackages = {"com.gtcloud.repository"}) // 指定该数据源操作的DAO接口包

public class PrimaryConfig {

@Autowired

@Qualifier("primaryDataSource")

private DataSource primaryDataSource;

@Primary

@Bean(name = "entityManagerPrimary")

public EntityManager entityManager(EntityManagerFactoryBuilder builder) {

return entityManagerFactoryPrimary(builder).getObject().createEntityManager();

}

@Primary

@Bean(name = "entityManagerFactoryPrimary")

public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary(EntityManagerFactoryBuilder builder) {

return builder

.dataSource(primaryDataSource)

.properties(getVendorProperties())

.packages("com.gtcloud.model") //设置实体类所在位置

.persistenceUnit("primaryPersistenceUnit")

.build();

}

private Map getVendorProperties() {

HashMap properties = new HashMap<>();

properties.put("hibernate.dialect",

env.getProperty("hibernate.dialect"));

properties.put("hibernate.ddl-auto",

"create");

properties.put("hibernate.physical_naming_strategy",

"org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy");

properties.put("hibernate.implicit_naming_strategy",

"org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy");

return properties;

}

@Autowired

private Environment env;

@Primary

@Bean(name = "transactionManagerPrimary")

public PlatformTransactionManager transactionManagerPrimary(EntityManagerFactoryBuilder builder) {

return new JpaTransactionManager(entityManagerFactoryPrimary(builder).getObject());

}

}

（2）从（次）数据源

@Configuration

@EnableTransactionManagement

@EnableJpaRepositories(

entityManagerFactoryRef = "entityManagerFactorySecondary",

transactionManagerRef = "transactionManagerSecondary",

basePackages = {"com.gtmove.repository"}) //设置DAO接口层所在包位置

public class SecondaryConfig {

@Autowired

@Qualifier("secondaryDataSource")

private DataSource secondaryDataSource;

@Bean(name = "entityManagerSecondary")

public EntityManager entityManager(EntityManagerFactoryBuilder builder) {

return entityManagerFactorySecondary(builder).getObject().createEntityManager();

}

@Bean(name = "entityManagerFactorySecondary")

public LocalContainerEntityManagerFactoryBean entityManagerFactorySecondary(EntityManagerFactoryBuilder builder) {

return builder

.dataSource(secondaryDataSource)

.properties(getVendorProperties())

.packages("com.gtmove.model") //设置实体类所在包的位置

.persistenceUnit("primaryPersistenceUnit")

.build();

}

private Map getVendorProperties() {

HashMap properties = new HashMap<>();

properties.put("hibernate.hbm2ddl.auto",

env.getProperty("hibernate.hbm2ddl.auto"));

properties.put("hibernate.ddl-auto",

env.getProperty("update"));

properties.put("hibernate.dialect",

env.getProperty("hibernate.dialect"));

properties.put("hibernate.physical_naming_strategy",

"org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy");

properties.put("hibernate.implicit_naming_strategy",

"org.springframework.boot.orm.jpa.hibernate.SpringImplicitNamingStrategy");

return properties;

}

@Autowired

private Environment env;

@Bean(name = "transactionManagerSecondary")

PlatformTransactionManager transactionManagerSecondary(EntityManagerFactoryBuilder builder) {

return new JpaTransactionManager(entityManagerFactorySecondary(builder).getObject());

}

}

这两个类主要配置每个数据源，包括事务管理器、以及实体管理器等配置。

注：必须要指定DAO接口所在的包以及实体类所在的包。每个数据源主要操作它指定的资源（DAO接口CURD、实体类）

五、注意点：

1、SpringBoot启动类必须关闭--程序启动加载的仓库（ EnableJpaRepositories），因为在数据源配置类中已经开启了。如果没有去掉，程序会跑不起来！

@SpringBootApplication(scanBasePackages = {""}) // 指定加载程序主包，存在默认值【可选】

//@EntityScan({""})

//@EnableJpaRepositories(basePackages = {""})

public class Gt3datamoverApplication {

public static void main(String[] args) {

SpringApplication.run(Gt3datamoverApplication.class, args);

}

}

2、如果需要对数据源连接的表进行DDL（正向生成表、程序启动动态更新表），需要在PrimaryConfig类中/SecondaryConfig类中的getVendorProperties()方法中进行手动设置（此教程都已设置好了！）二、application.yml中配置

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