應專案的需求，要把專案改成多資料來源，將兩張表單獨抽取出來，放入另一個數據庫中，由於spring cloud 架構不熟悉，也是花了點時間才做好。

１、禁用srping boot自動配置的單資料來源，
啟動類上加上註解@SpringBootApplication(exclude= DataSourceAutoConfiguration.class)

@SpringBootApplication(exclude= DataSourceAutoConfiguration.class)
@EnableDiscoveryClient
@EnableFeignClients
public class
 
 UserServerApplication {

    public static void main(String[] args) {
        SpringApplication.run(UserServerApplication.class, args);
    }
}

２、修改配置檔案，專案中用spring cloud config統一管理配置檔案的
在datasource節點下再加一個新資料來源配置，如下所示

datasource:
  user-server:
    url: jdbc:mysql://***?characterEncoding=utf-8&autoReconnect=true&f***
 

    username: ***
    password: ***
    driver-class-name: com.mysql.jdbc.Driver
    max-idle: 10
    max-wait: 10000
    min-idle: 5
    initial-size: 5
    validation-query: SELECT 1
    test-on-borrow: false
    test-while-idle: true
    time-between-eviction-runs-millis: 18800
  user-server-separate:
    url: jdbc:mysql://***?characterEncoding=utf-8&autoReconnect=true****
 

    username: ***
    password: ***
    driver-class-name: com.mysql.jdbc.Driver
    max-idle: 10
    max-wait: 10000
    min-idle: 5
    initial-size: 5
    validation-query: SELECT 1
    test-on-borrow: false
    test-while-idle: true
    time-between-eviction-runs-millis: 18800

３、分包　　兩個資料庫對應兩個實體類的包，xml檔案也一樣，分兩個資料夾,如下圖所示

domain 和 domain_separate 存放不同庫的實體類

mybatis和separate存放不同庫對應的xml檔案

４、建立新的資料來源

UcSeparateDataSourceConfig這是新配置的資料來源，具體內容如下

@Configuration
@MapperScan(basePackages = {"com.baojun.user_server.application.domain_separate"}, sqlSessionFactoryRef = "ucSeparateSqlSessionFactory")
public class UcSeparateDataSourceConfig {
    @Primary
    @Bean(name = "ucSeparateDataSource")
    @ConfigurationProperties(prefix = "datasource.user-server-separate")
    public DataSource dataSource() {
        return DataSourceBuilder.create().build();
    }

    @Primary
    @Bean(name = "ucSeparateTransactionManager")
    public DataSourceTransactionManager transactionManager(@Qualifier("ucSeparateDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Primary
    @Bean(name = "ucSeparateSqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("ucSeparateDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        factoryBean.setDataSource(dataSource);
        factoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:separate/*.xml"));
        return factoryBean.getObject();
    }

    @Bean(name = "ucSeparateSqlSessionTemplate")
    @Primary
    public SqlSessionTemplate sqlSessionTemplate(@Qualifier("ucSeparateSqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }

這裡要注意包路徑和xml檔案的路徑，
@ConfigurationProperties(prefix = “datasource.user-server-separate”)字首與配置檔案中一致

５、在需要更改資料來源的地方，加入對應的註解
@Resource(name=”ucSeparateSqlSessionTemplate”)這個就是新配置的資料來源

@Repository
public class CarDaoImpl extends BaseDaoImpl<Car> implements CarDao {
    public CarDaoImpl() {
    super(Car.class);
    }
    @Resource(name="ucSeparateSqlSessionTemplate")
    public void sqlSessionTemplate(SqlSessionTemplate sessionTemplate) {
    setSqlSessionTemplate(sessionTemplate);
    }
}