有一个这样子的需求，线上正在跑的业务，由于业务发展需要，需重新开发一套新系统，等新系统开发完成后，需要无缝对接切换，当初具体设计见草图。

添加依赖#

        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
            <!--scope=provided，说明它是在编译阶段生效，不需要打入包中，Lombok在编译期将带Lombok注解的Java文件正确编译为完整的Class文件-->
            <scope>provided</scope>
        </dependency>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--mybatis plus和spring boot整合-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.0</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.10</version>
        </dependency>

application.properties#

server.port=9999
spring.datasource.master.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.master.url=jdbc:mysql://127.0.0.1/test?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.master.username=root
spring.datasource.master.password=root

spring.datasource.slave.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.slave.jdbc-url=jdbc:mysql://127.0.0.1/test2?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.slave.username=root
spring.datasource.slave.password=root

2种方式创建DataSource#

Master配置，使用druid连接池#

import com.alibaba.druid.pool.DruidDataSource;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.env.Environment;

import javax.sql.DataSource;

/**
 * @Author：chenyanbin
 */
@Configuration
@MapperScan(basePackages = "com.example.demo.mapper", sqlSessionFactoryRef = "masterSqlSessionFactory")
public class MasterDataSourceConfig {
    @Autowired
    private Environment env;

    @Primary
    @Bean(name = "masterDataSource")
//    @ConfigurationProperties("spring.datasource.master")
    public DataSource masterDataSource() {
//        return DataSourceBuilder.create().build();
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl(env.getProperty("spring.datasource.master.url"));
        dataSource.setUsername(env.getProperty("spring.datasource.master.username"));
        dataSource.setPassword(env.getProperty("spring.datasource.master.password"));
        dataSource.setDriverClassName(env.getProperty("spring.datasource.master.driver-class-name"));
        //配置初始化大小、最小、最大
        dataSource.setMinIdle(10);
        //配置初始化大小、最小、最大
        dataSource.setMaxActive(200);
        //配置初始化大小、最小、最大
        dataSource.setInitialSize(10);
        //配置获取连接等待超时的时间
        dataSource.setMaxWait(60000);
        //配置一个连接在池中最小生存的时间,单位是毫秒
        dataSource.setMinEvictableIdleTimeMillis(300000);
        //配置间隔多久才进行一次检测,检测需要关闭的空闲连接,单位是毫秒
        dataSource.setTimeBetweenEvictionRunsMillis(60000);
        //默认的testWhileIdle=true,testOnBorrow=false,testOnReturn=false
        dataSource.setValidationQuery("SELECT 1");
        //申请连接时执行validationQuery检测连接是否有效
        dataSource.setTestOnBorrow(false);
        //建议配置为true，不影响性能，并且保证安全性。
        dataSource.setTestWhileIdle(true);
        //是否缓存preparedStatement，也就是PSCache
        dataSource.setPoolPreparedStatements(false);
        return dataSource;
    }

    @Bean(name = "masterSqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("masterDataSource") DataSource dataSource) throws Exception {
        MybatisSqlSessionFactoryBean sessionFactoryBean = new MybatisSqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);

        return sessionFactoryBean.getObject();
    }
}

Slave配置#

import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import org.apache.ibatis.session.SqlSessionFactory;
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 javax.sql.DataSource;

/**
 * @Author：chenyanbin
 */
@Configuration
@MapperScan(basePackages = "com.example.demo.mapper2",sqlSessionFactoryRef = "slaveSqlSessionFactory")
public class SlaveDataSourceConfig {
    @Bean(name = "slaveDataSource")
    @ConfigurationProperties("spring.datasource.slave")
    public DataSource slaveDataSource(){
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "slaveSqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("slaveDataSource") DataSource dataSource) throws Exception {
        MybatisSqlSessionFactoryBean sessionFactoryBean = new MybatisSqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        return sessionFactoryBean.getObject();
    }
}

注意#

　　master和slave扫描不同的mapper包路径！！！！！！

　　如果需要指定.xml文件，需这样配置！！！

    @Bean(name = "masterSqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("masterDataSource") DataSource dataSource) throws Exception {
        MybatisSqlSessionFactoryBean sessionFactoryBean = new MybatisSqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources("classpath:mapper/**/*.xml"));
        return sessionFactoryBean.getObject();
    }

启动类#

@SpringBootApplication(
        exclude = {DataSourceAutoConfiguration.class, MybatisPlusAutoConfiguration.class}
)

启动类上排查，自动装配，使用我们自定义的多数据源！！！

演示#

　　多个数据源，同时也是支持事务的

原文链接：
https://www.cnblogs.com/chenyanbin/p/15504125.html

作者：陈彦斌

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