Spring Boot + MyBatis-Plus 读写分离与多 Slave 负载均衡示例

一、项目结构

src/main/java/com/example/demo/
├── config/
│   ├── DataSourceConfig.java         # 数据源配置
│   ├── MyBatisPlusConfig.java        # MyBatis-Plus配置
├── constant/
│   ├── DataSourceType.java           # 数据源类型枚举
├── context/
│   ├── DataSourceContextHolder.java  # 数据源上下文
├── aspect/
│   ├── DataSourceAspect.java         # 注解驱动的数据源切换
│   ├── DataSourceRouteAspect.java    # 自动路由的数据源切换
├── annotation/
│   ├── DataSource.java               # 自定义数据源注解
├── loadbalancer/
│   ├── SlaveDataSourceLoadBalancer.java # 从库负载均衡器
├── mapper/
│   ├── UserMapper.java               # DAO接口
├── service/
│   ├── UserService.java              # 服务接口
│   ├── impl/
│       └── UserServiceImpl.java      # 服务实现
├── controller/
│   ├── UserController.java           # 控制器
└── DemoApplication.java              # 启动类

二、核心代码实现

（一）数据源类型枚举

// constant/DataSourceType.java
package com.example.demo.constant;public enum DataSourceType {MASTER,SLAVE_1,SLAVE_2,SLAVE_3
}

（二）数据源上下文

// context/DataSourceContextHolder.java
package com.example.demo.context;import com.example.demo.constant.DataSourceType;public class DataSourceContextHolder {private static final ThreadLocal<DataSourceType> contextHolder = new ThreadLocal<>();public static void setDataSource(DataSourceType type) {contextHolder.set(type);}public static DataSourceType getDataSource() {return contextHolder.get();}public static void clearDataSource() {contextHolder.remove();}
}

（三）动态数据源

// config/DynamicRoutingDataSource.java
package com.example.demo.config;import com.example.demo.context.DataSourceContextHolder;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;public class DynamicRoutingDataSource extends AbstractRoutingDataSource {@Overrideprotected Object determineCurrentLookupKey() {return DataSourceContextHolder.getDataSource();}
}

（四）数据源配置

// config/DataSourceConfig.java
package com.example.demo.config;import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import com.example.demo.constant.DataSourceType;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;@Configuration
public class DataSourceConfig {@Primary@Bean(name = "masterDataSource")@ConfigurationProperties("spring.datasource.master")public DataSource masterDataSource() {return DruidDataSourceBuilder.create().build();}@Bean(name = "slave1DataSource")@ConfigurationProperties("spring.datasource.slave1")public DataSource slave1DataSource() {return DruidDataSourceBuilder.create().build();}@Bean(name = "slave2DataSource")@ConfigurationProperties("spring.datasource.slave2")public DataSource slave2DataSource() {return DruidDataSourceBuilder.create().build();}@Bean(name = "slave3DataSource")@ConfigurationProperties("spring.datasource.slave3")public DataSource slave3DataSource() {return DruidDataSourceBuilder.create().build();}@Beanpublic DataSource dynamicDataSource() {DynamicRoutingDataSource dynamicDataSource = new DynamicRoutingDataSource();// 设置默认数据源dynamicDataSource.setDefaultTargetDataSource(masterDataSource());// 设置多数据源映射Map<Object, Object> targetDataSources = new HashMap<>();targetDataSources.put(DataSourceType.MASTER, masterDataSource());targetDataSources.put(