在springBoot mybatis 默认单数据源的情况下下划线转驼峰很简单，直接配置下面的配置就可以

#开启驼峰命名转换
mybatis.configuration.map-underscore-to-camel-case=true

然而在 springBoot mybatis 多数据源 情况下，这么配置是不生效的，需要在SqlSessionFactory中添加配置：configuration.setMapUnderscoreToCamelCase(true);

 @Bean(name = "mysqlSqlSessionFactory")
    public SqlSessionFactory mysqlSqlSessionFactory(@Qualifier("mysqlDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);

        org.apache.ibatis.session.Configuration configuration=new org.apache.ibatis.session.Configuration();
        configuration.setMapUnderscoreToCamelCase(true);
        bean.setConfiguration(configuration);

        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/*Mapper.xml"));
        return bean.getObject();
    }

当然在xml中一样，也是这样配置，而spring boot 推荐的风格，是bean代替xml配置，我也更喜欢这样。

下面贴出这个多数据源的全部代码配置：

import com.alibaba.druid.pool.DruidDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContextException;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.util.StringUtils;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "net.itxw.dao", sqlSessionTemplateRef = "mysqlSqlSessionTemplate")
public class MysqlDatasource {

    @Value("${spring.datasource.mysql.url}")
    private String url;

    @Value("${spring.datasource.mysql.username}")
    private String username;

    @Value("${spring.datasource.mysql.password}")
    private String password;

    @Value("${spring.datasource.mysql.driver-class-name}")
    private String driverClassName;


    @Bean(name = "mysqlDataSource")
    @Primary
    public DataSource mysqlDataSource() throws Exception {
        if (StringUtils.isEmpty(url))
            throw new ApplicationContextException("Database connection pool is not configured correctly");

        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);

        return dataSource;
    }

    @Bean(name = "mysqlSqlSessionFactory")
    public SqlSessionFactory mysqlSqlSessionFactory(@Qualifier("mysqlDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);

        org.apache.ibatis.session.Configuration configuration=new org.apache.ibatis.session.Configuration();
        configuration.setMapUnderscoreToCamelCase(true);
        bean.setConfiguration(configuration);

        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/*Mapper.xml"));
        return bean.getObject();
    }

    @Bean(name = "mysqlTransactionManager")
    public DataSourceTransactionManager mysqlTransactionManager(@Qualifier("mysqlDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean(name = "mysqlSqlSessionTemplate")
    public SqlSessionTemplate mysqlSqlSessionTemplate(@Qualifier("mysqlSqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}