Integrating MyBatis-Plus Dynamic DataSource with ShardingSphere-JDBC and Custom Load Balancing

Background: The original project used MyBatis-Plus dynamic data sources with @DS for read/write routing. As table sizes grew, horizontal sharding with ShardingJDBC was needed, but integrating both caused conflicts because most tutorials treat Sharding as a single data source, breaking @DS usage. This article presents a working solution.

1. Version Selection

ShardingJDBC has two main versions: the early Sharding-JDBC and the newer ShardingSphere-JDBC component of the ShardingSphere project.

Sharding-JDBC: released in 2016 as a lightweight JDBC layer for sharding and read‑write splitting.

ShardingSphere: evolved from Sharding-JDBC, released in 2018, provides a full distributed database ecosystem (Sharding-JDBC, Sharding-Proxy, Sharding-Sidecar, etc.).

The standalone ShardingJDBC is no longer maintained; the most commonly used version is 4.1.1.

<dependency>
    <groupId>org.apache.shardingsphere</groupId>
    <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
    <version>4.1.1</version>
</dependency>

ShardingSphere-JDBC is now the active project; we use version 5.2.1.

Official documentation: https://www.bookstack.cn/read/shardingsphere-5.1.0-zh/ecf18b21ab3f559c.md

<dependency>
    <groupId>org.apache.shardingsphere</groupId>
    <artifactId>shardingsphere-jdbc-core-spring-boot-starter</artifactId>
    <version>5.2.1</version>
</dependency>

2. Project Dependencies

All Maven dependencies required for the demo:

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
    <dependency>
        <groupId>com.zaxxer</groupId>
        <artifactId>HikariCP</artifactId>
        <version>3.4.5</version>
    </dependency>
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.4.0</version>
    </dependency>
    <!-- Read‑write splitting -->
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
        <version>3.3.2</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.33</version>
    </dependency>
    <dependency>
        <groupId>org.apache.shardingsphere</groupId>
        <artifactId>shardingsphere-jdbc-core-spring-boot-starter</artifactId>
        <version>5.2.1</version>
        <exclusions>
            <exclusion>
                <groupId>org.yaml</groupId>
                <artifactId>snakeyaml</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <!-- Add correct version of SnakeYAML required by ShardingSphere -->
    <dependency>
        <groupId>org.yaml</groupId>
        <artifactId>snakeyaml</artifactId>
        <version>1.33</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

3. Parameter Configuration

application.yml configuration for server, MyBatis‑Plus, Spring, sharding rules, read‑write splitting and SQL show.

server:
  port: 8080
mybatis-plus:
  mapper-locations: classpath*:mybatis/*.xml
  type-aliases-package: com.game.sharding.dto
  configuration:
    map-underscore-to-camel-case: false
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
spring:
  application:
    name: sharding-jdbc-test
  sharding-sphere:
    datasource:
      names: master,write,read,read2
      master:
        type: com.zaxxer.hikari.HikariDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        jdbc-url: jdbc:mysql://127.0.0.1:3306/game_dev?characterEncoding=utf-8&useSSL=false&allowMultiQueries=true&autoReconnect=true&serverTimezone=Asia/Shanghai
        username: root
        password: 123456
      write:
        type: com.zaxxer.hikari.HikariDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        jdbc-url: jdbc:mysql://127.0.0.1:3306/game_dev?characterEncoding=utf-8&useSSL=false&allowMultiQueries=true&autoReconnect=true&serverTimezone=Asia/Shanghai
        username: root
        password: 123456
      read:
        type: com.zaxxer.hikari.HikariDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        jdbc-url: jdbc:mysql://127.0.0.1:3306/game_dev_read?characterEncoding=utf-8&useSSL=false&allowMultiQueries=true&autoReconnect=true&serverTimezone=Asia/Shanghai
        username: root
        password: 123456
      read2:
        type: com.zaxxer.hikari.HikariDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        jdbc-url: jdbc:mysql://127.0.0.1:3306/game_dev_read?characterEncoding=utf-8&useSSL=false&allowMultiQueries=true&autoReconnect=true&serverTimezone=Asia/Shanghai
        username: root
        password: 123456
    rules:
      sharding:
        tables:
          team_msg:
            actual-data-nodes: customer-ds.team_msg_${0..1}
            table-strategy:
              standard:
                sharding-column: id
                sharding-algorithm-name: msg-id
        sharding-algorithms:
          msg-id:
            type: INLINE
            props:
              algorithm-expression: team_msg_${id % 2}
      readwrite-splitting:
        data-sources:
          customer-ds:
            load-balancer-name: customer-lb
            static-strategy:
              write-data-source-name: master
              read-data-source-names: read,read2,write
        load-balancers:
          customer-lb:
            type: CUSTOM
      props:
        sql-show: true

4. Code Configuration

The key is to register the MyBatis‑Plus data source as a ShardingSphere‑JDBC data source and expose four dynamic data source names (master, write, read, read2) so that the @DS annotation can locate them.

import com.baomidou.dynamic.datasource.DynamicRoutingDataSource;
import com.baomidou.dynamic.datasource.provider.AbstractDataSourceProvider;
import com.baomidou.dynamic.datasource.provider.DynamicDataSourceProvider;
import com.baomidou.dynamic.datasource.spring.boot.autoconfigure.DynamicDataSourceAutoConfiguration;
import com.baomidou.dynamic.datasource.spring.boot.autoconfigure.DynamicDataSourceProperties;
import org.apache.commons.lang3.StringUtils;
import org.apache.shardingsphere.driver.jdbc.adapter.AbstractDataSourceAdapter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Lazy;
import org.springframework.context.annotation.Primary;

import javax.annotation.Resource;
import javax.sql.DataSource;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

@Configuration
@AutoConfigureBefore({DynamicDataSourceAutoConfiguration.class, SpringBootConfiguration.class})
public class MyDataSourceConfiguration {

    /** mybatisplus dynamic datasource properties */
    @Autowired
    private DynamicDataSourceProperties properties;

    /** shardingjdbc datasource */
    @Lazy
    @Resource(name = "shardingSphereDataSource")
    private AbstractDataSourceAdapter shardingSphereDataSource;

    @Value("${spring.sharding-sphere.datasource.names}")
    private String shardingDataSourceNames;

    /** Register dynamic datasource so that @DS works with shardingjdbc */
    @Bean
    public DynamicDataSourceProvider dynamicDataSourceProvider() {
        if (StringUtils.isBlank(shardingDataSourceNames)) {
            throw new RuntimeException("配置 spring.sharding-sphere.datasource.names 不能为空");
        }
        String[] names = shardingDataSourceNames.split(",");
        return new AbstractDataSourceProvider() {
            @Override
            public Map<String, DataSource> loadDataSources() {
                Map<String, DataSource> dataSourceMap = new HashMap<>();
                Arrays.stream(names).forEach(name -> dataSourceMap.put(name, shardingSphereDataSource));
                return dataSourceMap;
            }
        };
    }

    /** Set the dynamic datasource as primary */
    @Primary
    @Bean
    public DataSource dataSource(DynamicDataSourceProvider dynamicDataSourceProvider) {
        DynamicRoutingDataSource dataSource = new DynamicRoutingDataSource();
        dataSource.setPrimary(properties.getPrimary());
        dataSource.setStrict(properties.getStrict());
        dataSource.setStrategy(properties.getStrategy());
        dataSource.setProvider(dynamicDataSourceProvider);
        dataSource.setP6spy(properties.getP6spy());
        dataSource.setSeata(properties.getSeata());
        return dataSource;
    }
}

5. Custom Complex Load‑Balancing Algorithm

ShardingSphere loads load‑balance algorithms via SPI. Implement ReadQueryLoadBalanceAlgorithm and register the class in META-INF/services/org.apache.shardingsphere.readwritesplitting.spi.ReadQueryLoadBalanceAlgorithm .

Implementation example:

public class CustomLoadBalanceAlgorithm implements ReadQueryLoadBalanceAlgorithm {
    private Properties props;

    public CustomLoadBalanceAlgorithm() {}

    @Override
    public void init(Properties props) {
        this.props = props;
    }

    @Override
    public String getDataSource(String name, String writeDataSourceName,
                               List<String> readDataSourceNames, TransactionConnectionContext context) {
        // Get the datasource key set by @DS
        String dsKey = DynamicDataSourceContextHolder.peek();
        if (StringUtils.isNotBlank(dsKey)) {
            if (writeDataSourceName.equals(dsKey)) {
                return dsKey;
            }
            if (readDataSourceNames.contains(dsKey)) {
                return dsKey;
            }
            throw new RuntimeException("@DS 配置错误，当前数据源[" + dsKey + "]不在SharingJDBC数据源列表[" + readDataSourceNames + "]中");
        }
        return writeDataSourceName;
    }

    @Override
    public String getType() {
        return "CUSTOM";
    }

    @Override
    public boolean isDefault() {
        return true;
    }

    @Override
    public Properties getProps() {
        return this.props;
    }
}

After adding the service file and the class, ShardingSphere will use the custom algorithm, and the MyBatis‑Plus @DS annotation works seamlessly with sharding.

6. Source Code Repository

Git repository: https://gitee.com/luowenjie98/sharing-sphere-mybatisplus-demo