请提供springboot连接双数据源的方法以及使用例子

好的，下面是Spring Boot连接双数据源的方法以及使用例子：

1. 引入相关依赖
在pom.xml文件中引入相关依赖，例如：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

<dependency>
    <groupId>com.zaxxer</groupId>
    <artifactId>HikariCP</artifactId>
    <version>3.4.5</version>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-dbcp2</artifactId>
    <version>2.7.0</version>
</dependency>

2. 配置application.properties文件
在application.properties文件中配置主数据源和副数据源的相关信息，例如：

# 主数据源配置
spring.datasource.url=jdbc:mysql://localhost:3306/maindb
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

# 副数据源配置
spring.datasource.secondary.url=jdbc:mysql://localhost:3306/seconddb
spring.datasource.secondary.username=root
spring.datasource.secondary.password=123456
spring.datasource.secondary.driver-class-name=com.mysql.jdbc.Driver

3. 创建数据源配置类
创建两个数据源的配置类，例如：

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "entityManagerFactoryPrimary",
        transactionManagerRef = "transactionManagerPrimary",
        basePackages = { "com.example.maindb.repository" })
public class PrimaryDataSourceConfig {

    @Bean(name = "dataSourcePrimary")
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource dataSource() {
        return DataSourceBuilder.create().build();
    }

    @Primary
    @Bean(name = "entityManagerFactoryPrimary")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(EntityManagerFactoryBuilder builder,
                                                                       @Qualifier("dataSourcePrimary") DataSource dataSource) {
        return builder
                .dataSource(dataSource)
                .packages("com.example.maindb.entity")
                .persistenceUnit("primary")
                .build();
    }

    @Primary
    @Bean(name = "transactionManagerPrimary")
    public PlatformTransactionManager transactionManager(
            @Qualifier("entityManagerFactoryPrimary") EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
}

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "entityManagerFactorySecondary",
        transactionManagerRef = "transactionManagerSecondary",
        basePackages = { "com.example.seconddb.repository" })
public class SecondaryDataSourceConfig {

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

    @Bean(name = "entityManagerFactorySecondary")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(EntityManagerFactoryBuilder builder,
                                                                        @Qualifier("dataSourceSecondary") DataSource dataSource) {
        return builder
                .dataSource(dataSource)
                .packages("com.example.seconddb.entity")
                .persistenceUnit("secondary")
                .build();
    }

    @Bean(name = "transactionManagerSecondary")
    public PlatformTransactionManager transactionManager(
            @Qualifier("entityManagerFactorySecondary") EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
}

4. 使用数据源
在代码中使用数据源，例如：

@Service
public class UserService {

    @Autowired
    private UserRepository mainUserRepository;

    @Autowired
    @Qualifier("secondaryEntityManagerFactory")
    private EntityManagerFactory secondaryEntityManagerFactory;

    public List<User> getAllMainUsers() {
        return mainUserRepository.findAll();
    }

    public List<User> getAllSecondaryUsers() {
        EntityManager entityManager = secondaryEntityManagerFactory.createEntityManager();
        Query query = entityManager.createQuery("SELECT u FROM User u");
        List<User> users = query.getResultList();
        entityManager.close();
        return users;
    }
}

以上就是Spring Boot连接双数据源的方法以及使用例子，希望能够对你有所帮助。