什麼是自定義Mybatis的配置規則？

答：即原來在mybatis配置檔案中中我們配置到<settings>標籤中的內容，如下第6-10行內容：

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 <configuration>
 6     <settings
 
>
 7         <setting name="lazyLoadingEnabled" value="true"/>
 8         <setting name="aggressiveLazyLoading" value="false"/>
 9         <setting name="logImpl" value="LOG4J"/>
10     </settings>
11     <environments default="development">
12         <environment id="development"
 
>
13             <transactionManager type="JDBC"/>
14             <dataSource type="POOLED">
15                 <property name="driver" value="com.mysql.jdbc.Driver"/>
16                 <property name="url"
17                           value="jdbc:mysql://localhost:3306/ssm?useSSL=true&amp;serverTimezone=Asia/Shanghai&amp;useUnicode=true&amp;characterEncoding=utf8"
 
/>
18                 <property name="username" value="root"/>
19                 <property name="password" value="123456"/>
20             </dataSource>
21         </environment>
22     </environments>
23     <mappers>
24         <!--<mapper resource="com/xj/mapper/UserMapper.xml"/>-->
25         <mapper class="com.xj.mapper.UserMapper"/>
26         <mapper class="com.xj.mapper.AccountMapper"/>
27 
28     </mappers>
29 </configuration>

在springboot我們不用編寫xml配置檔案，那麼我們該怎麼來配置這些設定呢？

答：編寫一個配置類，然後通過@Bean註解給容器中新增一個ConfigurationCustomizer型別的元件即可。如下例子所示：

@Configuration
public class MybatisConfig {

    @Bean
    public ConfigurationCustomizer configurationCustomizer(){
        return new ConfigurationCustomizer() {
            @Override
            public void customize(org.apache.ibatis.session.Configuration configuration) {
                configuration.setLazyLoadingEnabled(true);
                configuration.setMapUnderscoreToCamelCase(true);
                configuration.setLogImpl(Log4jImpl.class);
            }
        };
    }
}

Mybatis中可以配置的設定如下所示：