AOP+Nacos实现动态数据源切换

1. 添加依赖

<!-- Nacos配置中心 -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
    <version>2022.0.0.0</version>
</dependency>
<!-- 动态数据源（支持多数据源切换） -->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
    <version>4.2.0</version>
</dependency>

2. 配置Nacos连接

bootstrap.yml中配置Nacos服务地址及数据源配置文件：

spring:
  application:
    name: dynamic-datasource-demo
  cloud:
    nacos:
      config:
        server-addr: 127.0.0.1:8848
        group: DEFAULT_GROUP
        # 数据源配置文件ID（需在Nacos控制台提前创建）
        data-id: datasource-config.yaml
        file-extension: yaml
        refresh-enabled: true # 开启动态刷新

3. Nacos配置内容

在Nacos控制台创建datasource-config.yaml文件，内容如下：

datasource:
  dynamic:
    primary: master # 默认数据源
    datasource:
      master:
        url: jdbc:mysql://127.0.0.1:3306/master?useSSL=false
        username: root
        password: 123456
        driver-class-name: com.mysql.cj.jdbc.Driver
      slave1:
        url: jdbc:mysql://127.0.0.1:3306/slave1?useSSL=false
        username: root
        password: 123456
        driver-class-name: com.mysql.cj.jdbc.Driver

4. 动态数据源配置类

@Configuration
@Slf4j
public class DynamicDataSourceConfig {
    
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.dynamic")
    public DataSource dynamicDataSource() {
        // 自动读取Nacos配置中的datasource节点
        return new DynamicRoutingDataSource();
    }

    // 监听Nacos配置变更，刷新数据源
    @NacosConfigListener(dataId = "datasource-config.yaml", groupId = "DEFAULT_GROUP")
    public void onConfigChanged(String newConfig) {
        log.info("检测到数据源配置变更：{}", newConfig);
        DynamicDataSourceContextHolder.clear();
        DynamicRoutingDataSource ds = (DynamicRoutingDataSource) dynamicDataSource();
        ds.reload(); // 核心：触发数据源重载
    }
}

5. 数据源上下文管理器

public class DynamicDataSourceContextHolder {
    private static final ThreadLocal<String> CONTEXT = new ThreadLocal<>();
    
    public static void setDataSourceKey(String key) {
        CONTEXT.set(key);
    }
    
    public static String getDataSourceKey() {
        return CONTEXT.get();
    }
    
    public static void clear() {
        CONTEXT.remove();
    }
}

6. 动态切换实现（AOP切面）

@Aspect
@Component
public class DataSourceAspect {
    
    @Pointcut("@annotation(com.example.annotation.DS)")
    public void dataSourcePointCut() {}
    
    @Around("dataSourcePointCut()")
    public Object around(ProceedingJoinPoint joinPoint) throws Throwable {
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        DS ds = signature.getMethod().getAnnotation(DS.class);
        String oldKey = DynamicDataSourceContextHolder.getDataSourceKey();
        DynamicDataSourceContextHolder.setDataSourceKey(ds.value());
        try {
            return joinPoint.proceed();
        } finally {
            DynamicDataSourceContextHolder.setDataSourceKey(oldKey);
        }
    }
}

7. 自定义注解@DS

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DS {
    String value() default "master";
}

8. Service层使用示例

@Service
public class UserServiceImpl implements UserService {
    
    @Autowired
    private UserMapper userMapper;
    
    @DS("master")
    public void insert(User user) {
        userMapper.insert(user); // 写入主库
    }
    
    @DS("slave1")
    public User getById(Long id) {
        return userMapper.selectById(id); // 从slave1读取
    }
}