在SpringBoot+MyBatis项目中实现MySQL读写分离的实战指南

spring:
  datasource:
    master:
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://master-host:3306/db_name
      username: root
      password: master-pass
    slave:
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://slave-host:3306/db_name
      username: root
      password: slave-pass

public class DataSourceContextHolder {
    private static final ThreadLocal<String> CONTEXT_HOLDER = new ThreadLocal<>();
    
    public static void setDataSourceType(String dataSourceType) {
        CONTEXT_HOLDER.set(dataSourceType);
    }
    
    public static String getDataSourceType() {
        return CONTEXT_HOLDER.get();
    }
    
    public static void clearDataSourceType() {
        CONTEXT_HOLDER.remove();
    }
}

public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDataSourceType();
    }
}

@Aspect
@Component
public class DataSourceAspect {
    
    // 拦截所有Mapper层方法
    @Before("execution(* com.yourpackage.mapper..*.*(..))")
    public void beforeMethod(JoinPoint joinPoint) {
        String methodName = joinPoint.getSignature().getName();
        // 根据方法名判断是读还是写
        if (methodName.startsWith("get") || methodName.startsWith("select") || 
            methodName.startsWith("find") || methodName.startsWith("query")) {
            // 读方法切换到从库
            DataSourceContextHolder.setDataSourceType("slave");
        } else {
            // 写方法切换到主库
            DataSourceContextHolder.setDataSourceType("master");
        }
    }
    
    // 方法执行后清理数据源设置
    @After("execution(* com.yourpackage.mapper..*.*(..))")
    public void afterMethod() {
        DataSourceContextHolder.clearDataSourceType();
    }
}

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Master {
}