在Spring Boot中配置多個數據源可以通過以下步驟來實現：

1. 在pom.xml文件中添加Spring Boot對多數據源的支持依賴：

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

2. 在application.properties或application.yml配置文件中配置每個數據源的連接信息：

# 數據源1
spring.datasource.url=jdbc:mysql://localhost:3306/db1
spring.datasource.username=root
spring.datasource.password=root

# 數據源2
spring.datasource.secondary.url=jdbc:mysql://localhost:3306/db2
spring.datasource.secondary.username=root
spring.datasource.secondary.password=root

3. 創建多個DataSource bean，分別對應每個數據源：

@Configuration
public class DataSourceConfig {

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

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

4. 配置JpaVendorAdapter和EntityManagerFactory bean，指定每個數據源的JPA配置：

@Configuration
@EnableJpaRepositories(
        basePackages = "com.example.repository", 
        entityManagerFactoryRef = "entityManagerFactory",
        transactionManagerRef = "transactionManager"
)
public class JpaConfig {

    @Autowired
    @Qualifier("dataSource")
    private DataSource dataSource;

    @Autowired
    @Qualifier("secondaryDataSource")
    private DataSource secondaryDataSource;

    @Primary
    @Bean(name = "entityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(dataSource)
                .packages("com.example.domain")
                .persistenceUnit("primary")
                .build();
    }

    @Bean(name = "secondaryEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean secondaryEntityManagerFactory(EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(secondaryDataSource)
                .packages("com.example.domain")
                .persistenceUnit("secondary")
                .build();
    }

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

    @Bean(name = "secondaryTransactionManager")
    public PlatformTransactionManager secondaryTransactionManager(
            @Qualifier("secondaryEntityManagerFactory") EntityManagerFactory secondaryEntityManagerFactory) {
        return new JpaTransactionManager(secondaryEntityManagerFactory);
    }
}

5. 在需要使用數據源的地方使用@Qualifier注解指定具體的數據源：

@Service
public class MyService {

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

    // 使用entityManagerFactory進行數據庫操作
}

通過以上步驟，就可以在Spring Boot中成功配置多個數據源。