Spring Boot 动态多数据源核心思路与关键介绍

select * from test.user where id=1;
update test.user set name='AI' where id=1

/**
 * 多数据源切换注解
 * 用于在方法或类级别指定数据源
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DataSource {
    /**
     * 数据源名称
     * @return 数据源 key
     */
    String value() default "master";
}

public class DataSourceContextHolder {
    private static final ThreadLocal<String> CONTEXT_HOLDER = new ThreadLocal<>();
    public static void setDataSourceKey(String key) {
        CONTEXT_HOLDER.set(key);
    }
    public static String getDataSourceKey() {
        return CONTEXT_HOLDER.get();
    }
    public static void clearDataSourceKey() {
        CONTEXT_HOLDER.remove(); // ⚠️ 必须清理！
    }
}

public class DynamicRoutingDataSource extends AbstractRoutingDataSource {
    /**
     * 决定当前使用哪个数据源
     * @return 数据源 key
     */
    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDataSourceKey();
    }
}

@Aspect
@Component
@Order(1) // ⚠️ 关键：必须小于事务切面的 Order
public class DataSourceAspect {
    @Pointcut("@annotation(DataSource) || @within(DataSource)")
    public void dataSourcePointcut() {}
    @Before("dataSourcePointcut()")
    public void before(JoinPoint joinPoint) {
        Method method = ((MethodSignature) joinPoint.getSignature()).getMethod();
        // 优先方法注解，其次类注解
        DataSource dataSource = method.getAnnotation(DataSource.class);
        if (dataSource == null) {
            dataSource = joinPoint.getTarget().getClass().getAnnotation(DataSource.class);
        }
        if (dataSource != null) {
            DataSourceContextHolder.setDataSourceKey(dataSource.value());
        }
    }
    @After("dataSourcePointcut()")
    public void after(JoinPoint joinPoint) {
        DataSourceContextHolder.clearDataSourceKey();
    }
}

spring:
  application:
    name: boot-qoder
  datasource:
    # master 数据源配置
    master:
      driver-class-name: com.mysql.cj.jdbc.Driver
      jdbc-url: jdbc:mysql://127.0.0.1:3306/db_master?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai
      username: root
      password: root
    # slave1 数据源配置
    slave1:
      driver-class-name: com.mysql.cj.jdbc.Driver
      jdbc-url: jdbc:mysql://127.0.0.1:3306/db_slave1?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai
      username: root
      password: root
    # slave2 数据源配置
    slave2:
      driver-class-name: com.mysql.cj.jdbc.Driver
      jdbc-url: jdbc:mysql://127.0.0.1:3306/db_slave2?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai
      username: root
      password: root

@Configuration
@MapperScan(basePackages = "com.example.bootqoder.mapper", sqlSessionTemplateRef = "sqlSessionTemplate")
public class DataSourceConfig {
    /**
     * master 数据源
     * @return 数据源实例
     */
    @Bean(name = "masterDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.master")
    public DataSource masterDataSource() {
        return DataSourceBuilder.create()
                .type(com.zaxxer.hikari.HikariDataSource.class)
                .build();
    }
    /**
     * slave1 数据源
     * @return 数据源实例
     */
    @Bean(name = "slave1DataSource")
    @ConfigurationProperties(prefix = "spring.datasource.slave1")
    public DataSource slave1DataSource() {
        return DataSourceBuilder.create()
                .type(com.zaxxer.hikari.HikariDataSource.class)
                .build();
    }
    /**
     * slave2 数据源
     * @return 数据源实例
     */
    @Bean(name = "slave2DataSource")
    @ConfigurationProperties(prefix = "spring.datasource.slave2")
    public DataSource slave2DataSource() {
        return DataSourceBuilder.create()
                .type(com.zaxxer.hikari.HikariDataSource.class)
                .build();
    }
    /**
     * 创建动态路由数据源
     * @return 动态数据源
     */
    @Bean(name = "dynamicDataSource")
    @Primary
    public DataSource dynamicDataSource(
            @Qualifier("masterDataSource") DataSource masterDataSource,
            @Qualifier("slave1DataSource") DataSource slave1DataSource,
            @Qualifier("slave2DataSource") DataSource slave2DataSource) {
        DynamicRoutingDataSource routingDataSource = new DynamicRoutingDataSource();
        // 配置多个数据源
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put("master", masterDataSource);
        targetDataSources.put("slave1", slave1DataSource);
        targetDataSources.put("slave2", slave2DataSource);
        // 设置目标数据源
        routingDataSource.setTargetDataSources(targetDataSources);
        // 设置默认数据源
        routingDataSource.setDefaultTargetDataSource(masterDataSource);
        return routingDataSource;
    }
    /**
     * 创建 SqlSessionFactory
     * @param dataSource 数据源
     * @return SqlSessionFactory
     * @throws Exception 异常
     */
    @Bean(name = "sqlSessionFactory")
    @Primary
    public SqlSessionFactory sqlSessionFactory(@Qualifier("dynamicDataSource") DataSource dataSource) throws Exception {
        MybatisSqlSessionFactoryBean sessionFactory = new MybatisSqlSessionFactoryBean();
        sessionFactory.setDataSource(dataSource);
        // 设置 Mapper XML 文件位置
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        sessionFactory.setMapperLocations(resolver.getResources("classpath:mapper/*.xml"));
        // 设置 MyBatis Plus 配置
        MybatisConfiguration configuration = new MybatisConfiguration();
        configuration.setMapUnderscoreToCamelCase(true);
        sessionFactory.setConfiguration(configuration);
        return sessionFactory.getObject();
    }
    /**
     * 创建 SqlSessionTemplate
     * @param sqlSessionFactory SqlSessionFactory
     * @return SqlSessionTemplate
     */
    @Bean(name = "sqlSessionTemplate")
    @Primary
    public SqlSessionTemplate sqlSessionTemplate(@Qualifier("sqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}