Spring和MYbatis整合数据库下划线转驼峰

在Spring和MyBatis整合的情况下，可以通过在MyBatis的配置文件中配置一个插件来实现下划线转驼峰。

具体操作如下：

1. 在MyBatis的配置文件中添加以下插件配置：

   <plugins>
       <plugin interceptor="org.apache.ibatis.plugin.Interceptor">
           <property name="properties">
               <property name="helperDialect" value="mysql"/>
               <property name="offsetAsPageNum" value="true"/>
               <property name="rowBoundsWithCount" value="true"/>
               <property name="reasonable" value="true"/>
           </property>
           <property name="typeAliases">
               <typeAlias type="com.example.domain.User" alias="User"/>
           </property>
           <property name="mapperLocations" value="classpath:com/example/mapper/*.xml"/>
       </plugin>
   </plugins>

2. 在Spring的配置文件中配置一个Bean，将上一步中配置的插件添加到SqlSessionFactory中：

   <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
       <property name="dataSource" ref="dataSource"/>
       <property name="mapperLocations" value="classpath:com/example/mapper/*.xml"/>
       <property name="plugins">
           <array>
               <bean class="com.example.plugin.CamelCaseInterceptor"/>
           </array>
       </property>
   </bean>

3. 编写一个插件类，实现下划线转驼峰的逻辑：

   public class CamelCaseInterceptor implements Interceptor {
       @Override
       public Object intercept(Invocation invocation) throws Throwable {
           Object[] args = invocation.getArgs();
           MappedStatement ms = (MappedStatement) args[0];
           Object parameter = args[1];
           BoundSql boundSql = ms.getBoundSql(parameter);
           String sql = boundSql.getSql();
           // 下划线转驼峰
           sql = CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, sql);
           BoundSql newBoundSql = new BoundSql(ms.getConfiguration(), sql, boundSql.getParameterMappings(), boundSql.getParameterObject());
           MappedStatement newMs = copyFromMappedStatement(ms, new BoundSqlSqlSource(newBoundSql));
           args[0] = newMs;
           return invocation.proceed();
       }
   
       @Override
       public Object plugin(Object target) {
           return Plugin.wrap(target, this);
       }
   
       @Override
       public void setProperties(Properties properties) {
           // do nothing
       }
   
       private MappedStatement copyFromMappedStatement(MappedStatement ms, SqlSource newSqlSource) {
           MappedStatement.Builder builder = new MappedStatement.Builder(ms.getConfiguration(), ms.getId(), newSqlSource, ms.getSqlCommandType());
           builder.resource(ms.getResource());
           builder.fetchSize(ms.getFetchSize());
           builder.statementType(ms.getStatementType());
           builder.keyGenerator(ms.getKeyGenerator());
           builder.keyProperty(StringUtils.join(ms.getKeyProperties(), ","));
           builder.timeout(ms.getTimeout());
           builder.parameterMap(ms.getParameterMap());
           builder.resultMaps(ms.getResultMaps());
           builder.cache(ms.getCache());
           builder.useCache(ms.isUseCache());
           return builder.build();
       }
   }

通过以上步骤，即可实现在Spring和MyBatis整合的情况下将数据库中下划线命名的字段转换为驼峰命名的字段。