本文是向大家介绍Fluent Mybatis ，其实不是介绍，如果只是简单介绍，官方文档足够了。而是实战深入，比较适合已经有一定了解FluentMybatis的同学。

它能够实现多数据源接入，不使用默认傻瓜式配置，避免泛泛而谈，似是而非，转眼就忘

能够带来深入理解FluentMybatis的使用价值。

有兴趣的同学，不妨考虑适配Sharding-jdbc，Zdal-jdbc，组合使用，刚好可以锻炼提升一下

前言： 什么是Fluent Mybatis

简单入门: 地址

和其他plus 框架比较

-	Mybatis Plus	Fluent Mybatis
代码生成	生成 Entity, Mapper, Wrapper等文件, 并且Generator很好用	只生成Entity, 再通过编译生成 Mapper, Query, Update 和 SqlProvider
和Mybatis的共生关系	需要替换原有的SqlSessionFactoryBean	对Mybatis没有任何修改,原来怎么用还是怎么用
动态SQL构造方式	应用启动时, 根据Entity注解信息构造动态xml片段，注入到Mybatis解析器	应用编译时，根据Entity注解，编译生成对应方法的SqlProvider，利用mybatis的Mapper上@InsertProvider @SelectProvider @UpdateProvider注解关联
动态SQL结果是否容易DEBUG跟踪	不容易debug	容易，直接定位到SQLProvider方法上，设置断点即可
动态SQL构造	通过硬编码字段名称, 或者利用Entity的get方法的lambda表达式	通过编译手段生成对应的方法名，直接调用方法即可
字段变更后的错误发现	通过get方法的lambda表达的可以编译发现，通过字段编码的无法编译发现	编译时便可发现
不同字段动态SQL构造方法	通过接口参数方式	通过接口名称方式, FluentAPI的编码效率更高
语法渲染特点	无	通过关键变量select, update, set, and, or可以利用IDE语法渲染, 可读性更高

1. 配置案例

1.1 pom依赖jar包

        1.8
        UTF-8
        UTF-8
        2.3.7.RELEASE
        2.6
        1.1.17
        1.8.7
        8.0.17
    


    
        
            com.github.atool
            fluent-mybatis
            ${fluent-mybatis.version}
        
        
        
            com.github.atool
            fluent-mybatis-processor
            provided
            ${fluent-mybatis.version}
        
        
        
            com.alibaba
            druid-spring-boot-starter
            ${druid.version}
        

        
        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            2.1.4
        

1.2 数据源 注解配置

package com.csu.andrew.fluentmybatisdemo.common.config;

import cn.org.atool.fluent.mybatis.spring.MapperFactory;
import com.alibaba.druid.pool.DruidDataSource;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
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.core.io.support.ResourcePatternResolver;


@Configuration
@MapperScan(basePackages = "com.csu.andrew.fluentmybatisdemo.commondao.mapper", sqlSessionFactoryRef = "mgportraitbasecoreSqlSessionFactory")
@MapperScan(basePackages = "com.csu.andrew.fluentmybatisdemo.anotherdao.mapper", sqlSessionFactoryRef = "anotherSqlSessionFactory")
public class DataSourceCfg {
    @Bean(initMethod = "init")
    @Primary
    @ConfigurationProperties(prefix = "custom.datasource1.druid")
    public DruidDataSource getPrimaryDataSource() {
        return new DruidDataSource();
    }

    @Bean("mgportraitbasecoreSqlSessionFactory")
    @Primary
    @Autowired
    public SqlSessionFactoryBean sqlSessionFactoryBean(DruidDataSource druidDataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(druidDataSource);
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        // 路径正则表达式方式加载
        bean.setMapperLocations(resolver.getResources("classpath*:mapper/*.xml"));
        // 一个个文件加载
        // bean.setMapperLocations(
        //      new ClassPathResource("mapper/MyXmlMapper.xml"),
        //      new ClassPathResource("mapper/BatchUpdate.xml")
        // );
        org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        configuration.setLazyLoadingEnabled(true);
        configuration.setMapUnderscoreToCamelCase(true);
        bean.setConfiguration(configuration);
        return bean;
    }

    @Bean(initMethod = "init", value = "anotherDataSource")
    @ConfigurationProperties(prefix = "custom.datasource2.druid")
    public DruidDataSource getAnotherDataSource() {
        return new DruidDataSource();
    }


    @Bean("anotherSqlSessionFactory")
    @Autowired
    public SqlSessionFactoryBean sqlSessionFactoryAnotherBean(@Qualifier("anotherDataSource") DruidDataSource druidDataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(druidDataSource);
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        // 路径正则表达式方式加载
        bean.setMapperLocations(resolver.getResources("classpath*:anothermapper/*.xml"));
        // 一个个文件加载
        // bean.setMapperLocations(
        //      new ClassPathResource("mapper/MyXmlMapper.xml"),
        //      new ClassPathResource("mapper/BatchUpdate.xml")
        // );
        org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        configuration.setLazyLoadingEnabled(true);
        configuration.setMapUnderscoreToCamelCase(true);
        bean.setConfiguration(configuration);
        return bean;
    }

    @Bean
    public MapperFactory mapperFactory() {
        return new MapperFactory();
    }
}

1.3 application.properties 配置

# 应用名称
spring.application.name=fluent-mybatisdemo
# 应用服务 WEB 访问端口
server.port=8080


custom.db.ipport=dbserver:3306
custom.db.name=testdb
custom.db.user=**
custom.db.pass=***


custom.datasource1.druid.url=jdbc:mysql://${custom.db.ipport}/${custom.db.name}?characterEncoding=UTF-8&useUnicode=true&useSSL=false&tinyInt1isBit=false&allowPublicKeyRetrieval=true&serverTimezone=Asia/Shanghai
custom.datasource1.druid.username=${custom.db.user}
custom.datasource1.druid.password=${custom.db.pass}
custom.datasource1.druid.driver-class-name=com.mysql.cj.jdbc.Driver

custom.datasource2.druid.url=jdbc:mysql://${custom.db.ipport}/ry-vue?characterEncoding=UTF-8&useUnicode=true&useSSL=false&tinyInt1isBit=false&allowPublicKeyRetrieval=true&serverTimezone=Asia/Shanghai
custom.datasource2.druid.username=***
custom.datasource2.druid.password=***
custom.datasource2.druid.driver-class-name=com.mysql.cj.jdbc.Driver

2. 测试验证代码

@RestController
public class UserProvincePrecheckJobController {
    @Autowired
    SysDictDataDao sysDictDataDao;
    @Autowired
    UserProvincePrecheckJobDao userProvincePrecheckJobDao;

    @GetMapping(value = "/test1")
    @ResponseBody
    public List getUserProvincePrecheckJobDo() {
        return userProvincePrecheckJobDao.list();
    }

    @GetMapping(value = "/test2")
    @ResponseBody
    public List getSysDictDataDo() {
        return sysDictDataDao.list();
    }
}

2.1 验证数据源 testdb中的UserProvincePrecheckJobDo

2.2 验证数据源 ry-vue 中的 SysDictDataDo