Springboot2.x+mybatis多数据源（MySQL+Oracle）集成

  背景：最近项目需求需要同时查询MySQL和Oracle的数据，项目已经上线，总结一下，以备后续查看（该文档并不是完整的项目）。

项目基于gradle管理的标准的Web MVC架构：

build.gradle

group 'com.data.mult'
version '1.0-SNAPSHOT'

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'application'

mainClassName = 'com.data.mult.MultDataSourceApplication'
[compileJava, compileTestJava]*.options*.encoding = 'UTF-8'

sourceCompatibility = 1.8
targetCompatibility = 1.8

repositories {
    mavenLocal()
    maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
    maven { url "http://repo.maven.apache.org/maven2" }
    mavenCentral()
}

dependencies {
    compile group: 'com.alibaba', name: 'fastjson', version: '1.2.60'
    compile('org.springframework.boot:spring-boot-starter-web:2.1.5.RELEASE') {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
    }
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-log4j2', version: '2.1.5.RELEASE'
    compile('org.mybatis.spring.boot:mybatis-spring-boot-starter:2.0.1') {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter'
    }
    compile group: 'com.oracle.jdbc', name: 'ojdbc6', version: '11.2.0.4.0'
    compile group: "mysql", name: "mysql-connector-java", version: "8.0.11"
}

application.properties

#mybatis的配置文件路径
mybatis.config-locations=classpath:mybatis/mybatis-config.xml
#mybatis的mapper映射文件地址路径
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml
#mysql库1的配置
spring.datasource.primary.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.primary.jdbc-url=jdbc:mysql://localhost:3306/lwca?characterEncoding=utf8
spring.datasource.primary.username=root
spring.datasource.primary.password=123456


#oracle库的配置
spring.datasource.third.driverClassName=oracle.jdbc.OracleDriver
spring.datasource.third.jdbc-url=jdbc:oracle:thin:@localhost:1521:orcl
spring.datasource.third.username=root
spring.datasource.third.password=123456

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!-- 全局参数 -->
    <settings>
        <!-- 使全局的映射器启用或禁用缓存。 -->
        <setting name="cacheEnabled" value="true"/>
        <!-- 全局启用或禁用延迟加载。当禁用时，所有关联对象都会即时加载。 -->
        <setting name="lazyLoadingEnabled" value="true"/>
        <!-- 当启用时，有延迟加载属性的对象在被调用时将会完全加载任意属性。否则，每种属性将会按需要加载。 -->
        <setting name="aggressiveLazyLoading" value="true"/>
        <!-- 是否允许单条sql 返回多个数据集  (取决于驱动的兼容性) default:true -->
        <setting name="multipleResultSetsEnabled" value="true"/>
        <!-- 是否可以使用列的别名 (取决于驱动的兼容性) default:true -->
        <setting name="useColumnLabel" value="true"/>
        <!-- 允许JDBC 生成主键。需要驱动器支持。如果设为了true，这个设置将强制使用被生成的主键，有一些驱动器不兼容不过仍然可以执行。  default:false  -->
        <setting name="useGeneratedKeys" value="true"/>
        <!-- 指定 MyBatis 如何自动映射 数据基表的列 NONE：不隐射　PARTIAL:部分  FULL:全部  -->
        <setting name="autoMappingBehavior" value="PARTIAL"/>
        <!-- 这是默认的执行类型  （SIMPLE: 简单； REUSE: 执行器可能重复使用prepared statements语句；BATCH: 执行器可以重复执行语句和批量更新）  -->
        <setting name="defaultExecutorType" value="SIMPLE"/>
        <!-- 使用驼峰命名法转换字段。 -->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        <!-- 设置本地缓存范围 session:就会有数据的共享  statement:语句范围 (这样就不会有数据的共享 ) defalut:session -->
        <setting name="localCacheScope" value="SESSION"/>
        <!-- 设置但JDBC类型为空时,某些驱动程序 要指定值,default:OTHER，插入空值时不需要指定类型 -->
        <setting name="jdbcTypeForNull" value="NULL"/>
    </settings>
    <typeAliases>
        <typeAlias alias="Integer" type="java.lang.Integer"/>
        <typeAlias alias="Long" type="java.lang.Long"/>
        <typeAlias alias="HashMap" type="java.util.HashMap"/>
        <typeAlias alias="LinkedHashMap" type="java.util.LinkedHashMap"/>
        <typeAlias alias="ArrayList" type="java.util.ArrayList"/>
        <typeAlias alias="LinkedList" type="java.util.LinkedList"/>
    </typeAliases>
</configuration>

DataSource1Config.java

package com.data.mult.config;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
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 org.springframework.context.annotation.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "com.htiiot.htdata.dao.mapper1", sqlSessionTemplateRef  = "primarySqlSessionTemplate")
public class DataSource1Config {

    @Bean(name = "primaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.primary")
    @Primary
    public DataSource primaryDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "primarySqlSessionFactory")
    @Primary
    public SqlSessionFactory primarySqlSessionFactory(@Qualifier("primaryDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mybatis/mapper/map1/*"));
        return bean.getObject();
    }

    @Bean(name = "primaryTransactionManager")
    @Primary
    public DataSourceTransactionManager primaryTransactionManager(@Qualifier("primaryDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

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

}

DataSource3Config.java

package com.data.mult.config;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
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 org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "com.htiiot.htdata.dao.mapper3", sqlSessionTemplateRef  = "thirdSqlSessionTemplate")
public class DataSource3Config {

    @Bean(name = "thirdDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.third")
    public DataSource thirdDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "thirdSqlSessionFactory")
    public SqlSessionFactory thirdSqlSessionFactory(@Qualifier("thirdDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mybatis/mapper/map3/*"));
        return bean.getObject();
    }

    @Bean(name = "thirdTransactionManager")
    public DataSourceTransactionManager thirdTransactionManager(@Qualifier("thirdDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean(name = "thirdSqlSessionTemplate")
    public SqlSessionTemplate thirdSqlSessionTemplate(@Qualifier("thirdSqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

这里有几个点需要分开写：

1.配置application.properties中的配置前缀字符串

2.配置扫描mapperScan扫描的接口包路径

3.配置mapper.xml所在的目录。

总结：其他的跟单数据源的流程一样，该怎么写就怎么写。