在一些大型的項目中，通常會選擇多數據庫來滿足一些業務需求，此處講解使用springboot、mybatis和druid來配置多數據源

1、依賴配置

　　pom文件引入相關依賴

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version
 
>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.9</version>
        </dependency>

        <dependency>
            <
 
groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>    

　　application文件加入多數據源配置

　　spring:
        datasource:
            type: com.alibaba.druid.pool.DruidDataSource
            driverClassName: com.mysql.cj.jdbc.Driver
            druid:
                # 主庫數據源
                master:
                    url: jdbc:mysql://localhost:3306/springboot?serverTimezone=GMT%2B8
 
&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false
                    username: root
                    password: root
                # 從庫數據源
                slave:
                    url: jdbc:mysql://ip:3306/springboot?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false
                    username: root
                    password: root
                # 初始連接數
                initial-size: 10
                # 最大連接池數量
                max-active: 100
                # 最小連接池數量
                min-idle: 10
                # 配置獲取連接等待超時的時間
                max-wait: 60000
                # 打開PSCache，並且指定每個連接上PSCache的大小
                pool-prepared-statements: true
                max-pool-prepared-statement-per-connection-size: 20
                # 配置間隔多久才進行一次檢測，檢測需要關閉的空閑連接，單位是毫秒
                timeBetweenEvictionRunsMillis: 60000
                # 配置一個連接在池中最小生存的時間，單位是毫秒
                min-evictable-idle-time-millis: 300000
                validation-query: SELECT 1 FROM DUAL
                test-while-idle: true
                test-on-borrow: false
                test-on-return: false
                stat-view-servlet:
                    enabled: true
                    url-pattern: /monitor/druid/*
                filter:
                    stat:
                        log-slow-sql: true
                        slow-sql-millis: 1000
                        merge-sql: false
                    wall:
                        config:
                            multi-statement-allow: true
                            

2、添加主數據源和其他數據源配置

　　主數據源

@Configuration
//master mapper目錄
@MapperScan(basePackages = {"com.example.springbootdruidmultsource.mapper.master"}, sqlSessionFactoryRef = "masterSqlSessionFactory")
public class MasterDataSourcesConfig {
   
    private static final String MAPPER_LOCAL = "classpath:mybatis/master/*.xml";

    @ConfigurationProperties("spring.datasource.druid.master")
    @Primary
    @Bean(name = "masterDataSource")
    public DruidDataSource druidDataSource() {
        return new DruidDataSource();
    }

    @Bean(name = "masterTransactionManager")
    @Primary
    public DataSourceTransactionManager masterTransactionManager() {
        return new DataSourceTransactionManager(druidDataSource());
    }

    @Bean(name = "masterSqlSessionFactory")
    @Primary
    public SqlSessionFactory masterSqlSessionFactory(@Qualifier("masterDataSource") DataSource dataSource) throws Exception {
        final SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(MAPPER_LOCAL));
        return sessionFactoryBean.getObject();
    }
}

其中註解@Primary表示是主數據源

　　從數據源

@Configuration
@MapperScan(basePackages = {"com.example.springbootdruidmultsource.mapper.slave"}, sqlSessionFactoryRef = "slaveSqlSessionFactory")
public class SlaveDataSourcesConfig {

    private static final String MAPPER_LOCAL = "classpath:mybatis/slave/*.xml";

    @Bean(name = "slaveDataSource")
    @ConfigurationProperties("spring.datasource.druid.slave")
    public DruidDataSource druidDataSource() {
        return new DruidDataSource();
    }

　　 //其他數據源的事務管理器
    @Bean(name = "slaveTransactionManager")
    public DataSourceTransactionManager slaveTransactionManager() {
        return new DataSourceTransactionManager(druidDataSource());
    }

    @Bean(name = "slaveSqlSessionFactory")
    public SqlSessionFactory slaveSqlSessionFactory(@Qualifier("slaveDataSource") DruidDataSource dataSource) throws Exception {
        final SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(MAPPER_LOCAL));
        return sessionFactoryBean.getObject();
    }
}

其他的就是mybatis相關的一些內容，這裏不贅述

3、事務管理

對主數據原來說，直接在註解

    @Override
    @Transactional
    public void update(SysUser sysUser) {
        sysUserMapper.update(sysUser);
        int i = 10 / 0;
    }

對其他數據源來說，需要加上配置的事務管理器

    @Override
    @Transactional(value = "slaveTransactionManager")
    public void update(User user) {
        userMapper.update(user);
        int i = 10 / 0;
    }

源碼參照：Github

springboot 2.1.3 + mybatis + druid配置多數據源