一、简介

MybatisPlus中引用多数据库时，传统的配置就失效了，需要单独写配置来实现，下面就说一下具体应该如何操作

二、引入MybatisPlus多数据源配置

还是先看一下我的项目结构，Model是单独的模块，请自行创建

1、创建一个Maven项目，修改pom.xml文件增加对spring boot、mybatis plus、druid、mysql connector的引用

org.springframework.boot

spring-boot-dependencies

2.0.3.RELEASE

pom

import

org.springframework.boot

spring-boot-starter-web

com.alibaba

druid-spring-boot-starter

1.1.10

mysql

mysql-connector-java

5.1.9

com.baomidou

mybatis-plus-boot-starter

2.3

2、创建resources文件夹，并创建application.yml文件增加以下配置，此处不需要写mybatis plus的配置了，因为多数据源时这里的mybatis plus会失效，具体原因还没找到

#设置提供的服务名

spring:

application:

name: javademo-tyh-service-hotel#配置数据库

datasource:

type: com.alibaba.druid.pool.DruidDataSource

db1:

url: jdbc:mysql://10.11.12.237:3306/db_test?useUnicode=true&characterEncoding=utf8

username: root

password: root

driver-class-name: com.mysql.jdbc.Driver

db2:

url: jdbc:mysql://10.11.12.237:3306/tyh_test?useUnicode=true&characterEncoding=utf8

username: root

password: root

driver-class-name: com.mysql.jdbc.Driver#设置自己启动的端口

server:

port:12000

3、在resources文件夹下创建mapper文件夹，在其内部创建两个数据库的两张表的mapper.xml文件，分别编写一个自定义方法

BaseInfoMapper.xml

select count(*) from base_info;

UserInfoMapper.xml

select count(*) from user_info;

4、打开main方法所在的类并修改为如下代码

importorg.mybatis.spring.annotation.MapperScan;importorg.springframework.boot.SpringApplication;importorg.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

@MapperScan("javademo.tyh.service.hotel.mapper")//标记扫描的mapper位置

public classAppServiceHotel

{public static voidmain( String[] args )

{

SpringApplication.run(AppServiceHotel.class, args);

}

}

5、创建config文件夹，存放mybatis plus的相关配置，此内部的类很多都摘自官网，是按照他的方式进行实现的

创建枚举DBTypeEnum

/*** 多数据源枚举*/

public enumDBTypeEnum {

db1("db1"), db2("db2");privateString value;

DBTypeEnum(String value) {this.value =value;

}publicString getValue() {returnvalue;

}

}

创建数据源操作类DbContextHolder

public classDbContextHolder {private static final ThreadLocal contextHolder = new ThreadLocal<>();/*** 设置数据源

*@paramdbTypeEnum*/

public static voidsetDbType(DBTypeEnum dbTypeEnum) {

contextHolder.set(dbTypeEnum.getValue());

}/*** 取得当前数据源

*@return

*/

public staticString getDbType() {return(String) contextHolder.get();

}/*** 清除上下文数据*/

public static voidclearDbType() {

contextHolder.remove();

}

}

创建spring的DataSource抽象类 DynamicDataSource

importorg.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;/** 扩展Spring的AbstractRoutingDataSource抽象类，实现动态数据源。

* AbstractRoutingDataSource中的抽象方法determineCurrentLookupKey是实现数据源的route的核心，

* 这里对该方法进行Override。 【上下文DbContextHolder为一线程安全的ThreadLocal】*/

public class DynamicDataSource extendsAbstractRoutingDataSource {/*** 取得当前使用哪个数据源

*@return

*/@OverrideprotectedObject determineCurrentLookupKey(){returnDbContextHolder.getDbType();

}

}

创建MybatisPlusConfig配置类

importcom.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;importcom.baomidou.mybatisplus.MybatisConfiguration;importcom.baomidou.mybatisplus.entity.GlobalConfiguration;importcom.baomidou.mybatisplus.mapper.LogicSqlInjector;importcom.baomidou.mybatisplus.plugins.PaginationInterceptor;importcom.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean;importorg.apache.ibatis.plugin.Interceptor;importorg.apache.ibatis.session.SqlSessionFactory;importorg.apache.ibatis.type.JdbcType;importorg.springframework.beans.factory.annotation.Qualifier;importorg.springframework.boot.context.properties.ConfigurationProperties;importorg.springframework.context.annotation.Bean;importorg.springframework.context.annotation.Configuration;importorg.springframework.context.annotation.Primary;importorg.springframework.core.io.support.PathMatchingResourcePatternResolver;importjavax.sql.DataSource;importjava.util.HashMap;importjava.util.Map;/*** MybatisPlus配置*/@Configurationpublic classMybatisPlusConfig {//分页拦截器

@BeanpublicPaginationInterceptor paginationInterceptor() {return newPaginationInterceptor();

}//定义db1

@Bean(name = "db1")

@ConfigurationProperties(prefix= "spring.datasource.db1")//与配置文件中的层次结构相同

publicDataSource db1() {returnDruidDataSourceBuilder.create().build();

}//定义db2

@Bean(name = "db2")

@ConfigurationProperties(prefix= "spring.datasource.db2")//与配置文件中的层次结构相同

publicDataSource db2() {returnDruidDataSourceBuilder.create().build();

}/*** 动态数据源配置

*@return

*/@Bean

@Primarypublic DataSource multipleDataSource(@Qualifier("db1") DataSource db1, @Qualifier("db2") DataSource db2) {

DynamicDataSource dynamicDataSource= newDynamicDataSource();

Map targetDataSources = new HashMap<>();

targetDataSources.put(DBTypeEnum.db1.getValue(), db1);

targetDataSources.put(DBTypeEnum.db2.getValue(), db2);

dynamicDataSource.setTargetDataSources(targetDataSources);

dynamicDataSource.setDefaultTargetDataSource(db1);returndynamicDataSource;

}

@Bean("sqlSessionFactory")public SqlSessionFactory sqlSessionFactory() throwsException {//***导入MybatisSqlSession配置***

MybatisSqlSessionFactoryBean sqlSessionFactory = newMybatisSqlSessionFactoryBean();//指明数据源

sqlSessionFactory.setDataSource(multipleDataSource(db1(), db2()));//指明mapper.xml位置(配置文件中指明的xml位置会失效用此方式代替，具体原因未知)

sqlSessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:/mapper/**Mapper.xml"));//指明实体扫描(多个package用逗号或者分号分隔)

sqlSessionFactory.setTypeAliasesPackage("javademo.tyh.model.base;javademo.tyh.model.hotel");//***导入Mybatis配置***

MybatisConfiguration configuration = newMybatisConfiguration();

configuration.setJdbcTypeForNull(JdbcType.NULL);

configuration.setMapUnderscoreToCamelCase(true);

configuration.setCacheEnabled(false);

sqlSessionFactory.setConfiguration(configuration);

sqlSessionFactory.setPlugins(newInterceptor[]{paginationInterceptor()});//***导入全局配置***

sqlSessionFactory.setGlobalConfig(globalConfiguration());returnsqlSessionFactory.getObject();

}/*** 在代码中配置MybatisPlus替换掉application.yml中的配置

*@return

*/@BeanpublicGlobalConfiguration globalConfiguration() {

GlobalConfiguration conf= new GlobalConfiguration(newLogicSqlInjector());//主键类型 0:数据库ID自增, 1:用户输入ID,2:全局唯一ID (数字类型唯一ID), 3:全局唯一ID UUID

conf.setIdType(0);//字段策略(拼接sql时用于判断属性值是否拼接) 0:忽略判断,1:非NULL判断,2:非空判断

conf.setFieldStrategy(2);//驼峰下划线转换含查询column及返回column(column下划线命名create_time，返回java实体是驼峰命名createTime，开启后自动转换否则保留原样)

conf.setDbColumnUnderline(true);//是否动态刷新mapper

conf.setRefresh(true);returnconf;

}

}

6、创建mapper文件夹用于存放于xml对应的mapper接口

BaseInfoMapper

importcom.baomidou.mybatisplus.mapper.BaseMapper;importjavademo.tyh.model.hotel.BaseInfoModel;importorg.springframework.stereotype.Component;

@Componentpublic interface BaseInfoMapper extends BaseMapper{//自定义方法

intlistCount();

}

UserInfoMapper

importcom.baomidou.mybatisplus.mapper.BaseMapper;importjavademo.tyh.model.hotel.UserInfoModel;importorg.springframework.stereotype.Component;

@Componentpublic interface UserInfoMapper extends BaseMapper{//自定义方法

intlistCount();

}

7、创建service文件夹用于存放业务逻辑类

importjavademo.tyh.model.hotel.BaseInfoModel;importjavademo.tyh.model.hotel.UserInfoModel;importjavademo.tyh.service.hotel.config.DBTypeEnum;importjavademo.tyh.service.hotel.config.DbContextHolder;importjavademo.tyh.service.hotel.mapper.BaseInfoMapper;importjavademo.tyh.service.hotel.mapper.UserInfoMapper;importorg.springframework.beans.factory.annotation.Autowired;importorg.springframework.stereotype.Service;

@Servicepublic classHotelService {

@Autowired

BaseInfoMapper baseMapper;

@Autowired

UserInfoMapper userMapper;public voidtestDynamicDb() {//使用db1

DbContextHolder.setDbType(DBTypeEnum.db1);

BaseInfoModel baseModel= baseMapper.selectById(1);int baseCount =baseMapper.listCount();

System.out.println("db1=" +baseModel.getNickname());//使用db2

DbContextHolder.setDbType(DBTypeEnum.db2);

UserInfoModel userModel= userMapper.selectById(1);int userCount =userMapper.listCount();

System.out.println("db2=" +userModel.getUsername());

}

}

8、创建controller文件夹编写一个controller和action用于测试

importjavademo.tyh.service.hotel.service.HotelService;importorg.springframework.beans.factory.annotation.Autowired;importorg.springframework.stereotype.Controller;importorg.springframework.web.bind.annotation.RequestMapping;importorg.springframework.web.bind.annotation.ResponseBody;

@Controller

@RequestMapping("/hotel")public classHotelController {

@Autowired

HotelService service;

@ResponseBody

@RequestMapping("/test")public voidtest() {

service.testDynamicDb();

}

}

9、创建自己的实体Model，get/set方法自己生成吧

BaseInfoModel

importcom.baomidou.mybatisplus.annotations.TableName;importjava.time.LocalDateTime;

@TableName("base_info")public classBaseInfoModel {private intid;privateString nickname;privateLocalDateTime updateTime;

}

UserInfoModel

importcom.baomidou.mybatisplus.annotations.TableName;importjava.time.LocalDateTime;

@TableName("user_info")public classUserInfoModel {private intid;privateString username;privateString password;private intsex;private intage;privateLocalDateTime createTime;

}

OK，至此Mybatis Plus多数据源配置Demo就完成了，可以运行http://localhost:12000/hotel/test看一下console控制台会得到以下输出，db1和db2就切换成功了