springboot之mybatis多数据源解决方案

悠然小熠
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一、多数据源配置的使用场景

  1. 多数据库：当一个公司的业务复杂（数据量大）,多个子项目各用各的数据库，导致数据分布在不同的数据库中时，就可能会需要使用多数据源。 这种场景下，数据库拆分了，但应用没拆，涉及数据共享。

  2. 读写分离：为了解决数据库的读性能瓶颈（读比写性能更高，写锁会影响读阻塞，从而影响读的性能），很多数据库采用主从架构。一台主数据库服务器对外提供增删改业务的生产服务器，另一台或多台从数据库服务器主要进行读的操作。这种方式可以通过中间件（如ShardingSphere、mycat、mysql-proxy、TDDL等）实现，但如果没有专门的中间件团队搭建读写分离基础设施，业务开发人员可能需要自行实现读写分离。

二、多数据源配置步骤

1.添加依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.neo</groupId>
	<artifactId>spring-boot-mybatis-xml-mulidatasource</artifactId>
	<version>1.0.0</version>
	<packaging>jar</packaging>

	<name>spring-boot-mybatis-xml-mulidatasource</name>
	<description>Demo project for Spring Boot and mybatis</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>3.0.0</version>
		<relativePath/> 
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<java.version>17</java.version>
	</properties>

	<dependencies>
		<dependency>
	        <groupId>org.springframework.boot</groupId>
	        <artifactId>spring-boot-starter-web</artifactId>
	    </dependency>
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>3.0.0</version>
		</dependency>
	     <dependency>
	        <groupId>mysql</groupId>
	        <artifactId>mysql-connector-java</artifactId>
	    </dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
		</dependency>
		<dependency>
			<groupId>org.junit.vintage</groupId>
			<artifactId>junit-vintage-engine</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.hamcrest</groupId>
					<artifactId>hamcrest-core</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
	
</project>

2.配置多个数据源 application.properties

spring.datasource.master.jdbc-url=jdbc:mysql://localhost:3306/master?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
spring.datasource.master.username=root
spring.datasource.master.password=root
spring.datasource.master.driver-class-name=com.mysql.cj.jdbc.Driver


spring.datasource.slave.jdbc-url=jdbc:mysql://localhost:3306/slave?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
spring.datasource.slave.username=root
spring.datasource.slave.password=root
spring.datasource.slave.driver-class-name=com.mysql.cj.jdbc.Driver

3.数据源配置类

MasterDataSource.java

package com.example.config.datasource;

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.autoconfigure.jdbc.DataSourceBuilder;
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.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "com.example.dao.master", sqlSessionTemplateRef  = "masterSqlSessionTemplate")
public class DCSDataSource {
    @Bean(name = "masterDataSource")
    @ConfigurationProperties(prefix = "master.datasource")
    @Primary
    public DataSource testDataSource() {
       return DataSourceBuilder.create().build();
    }

    @Bean(name = "masterSqlSessionFactory")
    @Primary
    public SqlSessionFactory testSqlSessionFactory(@Qualifier("masterDataSource") DataSource dataSource) throws Exception {
       SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
       bean.setDataSource(dataSource);
       bean.setTypeAliasesPackage("com.example.master.model");
       // bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mybatis/mapper/master/*.xml"));
       return bean.getObject();
    }

    @Bean(name = "masterTransactionManager")
    @Primary
    public DataSourceTransactionManager testTransactionManager(@Qualifier("masterDataSource") DataSource dataSource) {
       return new DataSourceTransactionManager(dataSource);
    }

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

SlaveDataSource.java

package com.example.config.datasource;

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.autoconfigure.jdbc.DataSourceBuilder;
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.jdbc.datasource.DataSourceTransactionManager;

import javax.sql.DataSource;

@Configuration
@MapperScan(basePackages = "com.example.dao.basedata", sqlSessionTemplateRef  = "slaveSqlSessionTemplate")
public class SlaveDataDataSource {
    @Bean(name = "slaveDataSource")
    @ConfigurationProperties(prefix = "slave.datasource")
    public DataSource testDataSource() {
       return DataSourceBuilder.create().build();
    }

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

    @Bean(name = "slaveTransactionManager")
    public DataSourceTransactionManager testTransactionManager(@Qualifier("slaveDataSource") DataSource dataSource) {
       return new DataSourceTransactionManager(dataSource);
    }

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

}
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