项目中遇到springboot2.0要配置多数据源的情况，在这里记录下，原理只有一个数据源，直接配置在application.yml下面了，由于要转多数据源，则需要配置多个数据源类。同时application.yml也要相应的添加上数据库配置。
application.yml:
mybatis:mapperLocations: classpath:mapper/*.xmlconfiguration:callSettersOnNulls: true # mybatis3 空字段null字段不返回 设置为true则返回nullmapUnderscoreToCamelCase: truespring:datasource:aa:driverClassName: com.mysql.jdbc.Driver#开发环境jdbc-url: jdbc:mysql://192.168.1.1:3306/aa?useUnicode=true&characterEncoding=utf-8&useOldAliasMetadataBehavior=trueusername: rootpassword: rootmax-active: 10initial-size: 5max-idle: 5min-idle: 1test-while-idle: truetest-on-borrow: truevalidation-query: SELECT 1time-between-eviction-runs-millis: 5000min-evictable-idle-time-millis: 60000bb:driver-class-name: com.mysql.jdbc.Driver#开发环境jdbc-url: jdbc:mysql://192.168.1.2:3306/bb?useUnicode=true&characterEncoding=utf-8&useOldAliasMetadataBehavior=trueusername: rootpassword: rootmax-active: 10initial-size: 5max-idle: 5min-idle: 1test-while-idle: truetest-on-borrow: truevalidation-query: SELECT 1time-between-eviction-runs-millis: 5000min-evictable-idle-time-millis: 60000上面配置要注意到jdbc-url,这个在springboot1.x的时候配的是url,这里需要改成jdbc-url否则到时候启动时会报错：jdbcUrl is required with driverClassName.网上也有解决方案：点我查看。这是第一个问题吧。
好了，按上面的配置完，application.yml就配置完成了。接着编写配置类，这里只写两个，放在springboot能扫描到的地方就行：
主
package com.weimingfj.background.datasource;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.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
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 javax.sql.DataSource;
//basePackages 配置的是mapper接口对应的包
@Configuration
@MapperScan(basePackages = "com.xxx.mapper.aaPackage", sqlSessionTemplateRef = "aaSqlSessionTemplate")
public class DataSourceTmsConfig {@Bean@ConfigurationProperties(prefix = "mybatis.configuration")public org.apache.ibatis.session.Configuration globalConfiguration() {return new org.apache.ibatis.session.Configuration();}@Bean(name = "aaDataSource")@ConfigurationProperties(prefix = "spring.datasource.aa")@Primarypublic DataSource tmsDataSource() {return DataSourceBuilder.create().build();}@Bean(name = "aaSqlSessionFactory")@Primarypublic SqlSessionFactory aaSqlSessionFactory(@Qualifier("aaDataSource") DataSource dataSource, org.apache.ibatis.session.Configuration config) throws Exception {SqlSessionFactoryBean bean = new SqlSessionFactoryBean();bean.setDataSource(dataSource);bean.setConfiguration(config);bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml"));return bean.getObject();}@Bean(name = "aaTransactionManager")@Primarypublic DataSourceTransactionManager aaTransactionManager(@Qualifier("aaDataSource") DataSource dataSource) {return new DataSourceTransactionManager(dataSource);}@Bean(name = "aaSqlSessionTemplate")@Primarypublic SqlSessionTemplate aaSqlSessionTemplate(@Qualifier("aaSqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {return new SqlSessionTemplate(sqlSessionFactory);}}
次：
package com.weimingfj.background.datasource;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.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;import javax.sql.DataSource;/*** Created by summer on 2016/11/25.*/
@Configuration
@MapperScan(basePackages = "com.xxx.mapper.bb", sqlSessionTemplateRef = "bbSqlSessionTemplate")
public class DataSourceWlgjConfig {@Bean(name = "bbDataSource")@ConfigurationProperties(prefix = "spring.datasource.bb")public DataSource bbDataSource() {return DataSourceBuilder.create().build();}@Bean(name = "bbSqlSessionFactory")public SqlSessionFactory bbSqlSessionFactory(@Qualifier("bbDataSource") DataSource dataSource, org.apache.ibatis.session.Configuration config) throws Exception {SqlSessionFactoryBean bean = new SqlSessionFactoryBean();bean.setDataSource(dataSource);
// bean.setConfiguration(config);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/*.xml"));return bean.getObject();}@Bean(name = "bbTransactionManager")public DataSourceTransactionManager wlgjTransactionManager(@Qualifier("bbDataSource") DataSource dataSource) {return new DataSourceTransactionManager(dataSource);}@Bean(name = "bbSqlSessionTemplate")public SqlSessionTemplate wlgjSqlSessionTemplate(@Qualifier("bbSqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {return new SqlSessionTemplate(sqlSessionFactory);}}
这里要注意的就是两点，对应的关键代码为：
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/*.xml"));由于我在代码中用到mybatis的下划线转驼峰配置：mapUnderscoreToCamelCase: true，当没有写上面的bean.setConfiguration(configuration);这段在配置类中将配置写入的话，只在application.yml中使用是不会生效的，原因是用了多数据源之后，springboot不在会替我们自动配置，而需要我们在这里手动配。原因可参看：点我查看或点我查看。
然后bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml"));这段是是同样的道理，如果不在这里手动配置的话，只在application.yml中配置同样不会生效。
还有一个重要的点就是，如果你的配置类的basePackages中进行了配置，主配置的basePackages不能够覆盖到次的basePackages，否则全部都会走主的数据源进行数据操作，次的就失效了。
最后附上springboot多个example，里面就有多数据源配置的源码例子哦：点我查看