mybatis-config.xml是支持配置多種數據庫的，本文將介紹在Spring Boot中使用配置類來配置。

1. 配置application.yml

# mybatis配置
mybatis:check-config-location: falsetype-aliases-package: ${base.package}.modelconfiguration:map-underscore-to-camel-case: true# 二級緩存的總開關cache-enabled: falsemapper-locations: classpath:mapping/*.xml

2. 新增數據源配置類

/*** 數據源配置* @author simon* @date 2019-02-18*/
@Configuration
public class DataSourceConfig {@Value("${mybatis.mapper-locations}")private String mapperLocations;@Primary@Bean@ConfigurationProperties("spring.datasource.druid")public DataSource dataSource(){return DruidDataSourceBuilder.create().build();}@Beanpublic JdbcTemplate jdbcTemplate(){return new JdbcTemplate(dataSource());}@Beanpublic DatabaseIdProvider databaseIdProvider(){DatabaseIdProvider databaseIdProvider = new VendorDatabaseIdProvider();Properties p = new Properties();p.setProperty("Oracle", "oracle");p.setProperty("MySQL", "mysql");p.setProperty("PostgreSQL", "postgresql");p.setProperty("DB2", "db2");p.setProperty("SQL Server", "sqlserver");databaseIdProvider.setProperties(p);return databaseIdProvider;}@Beanpublic SqlSessionFactoryBean sqlSessionFactoryBean() throws Exception {SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();factoryBean.setDataSource(dataSource());factoryBean.setDatabaseIdProvider(databaseIdProvider());factoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(mapperLocations));return factoryBean;}
}

3. 在mapper.xml中使用

方法1

  <select id="findAuthorityByUrl" resultType="java.lang.String" databaseId="mysql">SELECTgroup_concat( tsma.authority ) as authorityFROMt_side_menu tsmLEFT JOIN t_side_menu_authority tsma ON tsm.id = tsma.side_menu_id</select><select id="findAuthorityByUrl" resultType="java.lang.String" databaseId="postgresql">SELECTstring_agg( tsma.authority, ',') as authorityFROMt_side_menu tsmLEFT JOIN t_side_menu_authority tsma ON tsm.id = tsma.side_menu_id</select>

方法2

  <select id="selectByPids" parameterType="String" resultMap="SuperResultMap">SELECTtsm.*,<if test="_databaseId == 'mysql'">group_concat( tsma.authority ) as authority</if><if test="_databaseId == 'postgresql'">string_agg( tsma.authority, ',') as authority</if>FROMt_side_menu tsmLEFT JOIN t_side_menu_authority tsma ON tsm.id = tsma.side_menu_idWHERE pid IN (#{pids})GROUP BYtsm.id</select>

題外話

如果有興趣，請給oauthserer項目一個star。oauthserver是一個基于Spring Boot Oauth2的完整的獨立的Oauth2 Server微服務。項目的目的是，僅僅需要創建相關數據表，修改數據庫的連接信息，你就可以得到一個Oauth2 Server微服務。