一、简介：mybatis是支持属性使用驼峰的命名

如下java代码

public class Role {
    private Integer id;
    private String roleName;
    private String roleKey;
    private Integer orderNum;
    private Integer roleType;
    private String remark;
    ...省略set,get方法
}

列名是有下划线的

像上面这样设计是需要配置下划线与驼峰式命名规则的映射

mapUnderscoreToCamelCase：是否启用下划线与驼峰式命名规则的映射（如first_name => firstName）

 <setting name="mapUnderscoreToCamelCase" value="true"/>

二、在SSM整合中的配置

方式一:
在applicationContext-dao.xml中引入mybatis配置

<!-- 配置sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <!-- 数据库连接池 -->
    <property name="dataSource" ref="dataSource"/>
    <!-- 加载Mybatis全局配置文件 -->
    <property name="configLocation" value="/WEB-INF/classes/mybatis/SqlMapConfig.xml"/>
</bean>

SqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--配置全局属性-->
    <settings>
        <!--开启驼峰命名转换-->
       <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>

方式二:
在applicationContext-dao.xml中直接配置

<bean class="org.mybatis.spring.SqlSessionFactoryBean" id="factory">
    <property name="dataSource" ref="dataSource"/>
    <property name="typeAliasesPackage" value="com.glc.domain"/>
    
    <property name="configuration">
        <bean class="org.apache.ibatis.session.Configuration">
            <property name="mapUnderscoreToCamelCase" value="true"/>
        </bean>
    </property>

</bean>

三、亲测代码配置文件spring-mybatis.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/tx
       http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!-- 扫描service包下所有使用注解的类型 -->
    <context:component-scan base-package="com.chatRobot.service"/>

    <!-- 配置数据库相关参数properties的属性：${url} -->
    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!-- 数据库连接池 -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="user" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="maxPoolSize" value="${c3p0.maxPoolSize}"/>
        <property name="minPoolSize" value="${c3p0.minPoolSize}"/>
        <property name="autoCommitOnClose" value="${c3p0.autoCommitOnClose}"/>
        <property name="checkoutTimeout" value="${c3p0.checkoutTimeout}"/>
        <property name="acquireRetryAttempts" value="${c3p0.acquireRetryAttempts}"/>
    </bean>

    <!-- 配置SqlSessionFactory对象 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 注入数据库连接池 -->
        <property name="dataSource" ref="dataSource"/>
        <!-- 扫描model包 使用别名 -->
        <property name="typeAliasesPackage" value="com.chatRobot.model"/>
        <!-- 扫描sql配置文件:mapper需要的xml文件 -->
        <property name="mapperLocations" value="classpath:mapper/*.xml"/>

        <property name="configuration">
            <bean class="org.apache.ibatis.session.Configuration">
                <!--mybatis支持属性使用驼峰的命名-->
                <property name="mapUnderscoreToCamelCase" value="true"/>
            </bean>
        </property>
    </bean>

    <!-- 配置扫描Dao接口包，动态实现Dao接口，注入到spring容器中 -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 注入sqlSessionFactory -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!-- 给出需要扫描Dao接口包 -->
        <property name="basePackage" value="com.chatRobot.dao"/>
    </bean>

    <!-- 配置事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <!-- 注入数据库连接池 -->
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!-- 配置基于注解的声明式事务 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>

</beans>