spring+mybatis整合多数据源
本例 SpringBoot 版本：2.3.0.RELEASE
一、创建数据库与表结构数据
CREATE DATABASE `test1` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
USE `test1`;
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
`id` int(5) NOT NULL AUTO_INCREMENT,
`name` varchar(36) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
`age` int(3) NOT NULL,
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 4 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;
INSERT INTO `student` VALUES (1, '张梦为', 13);
INSERT INTO `student` VALUES (2, '上官婉儿', 22);
INSERT INTO `student` VALUES (3, '唐因', 25);CREATE DATABASE `test2` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
USE `test2`;
DROP TABLE IF EXISTS `lesson`;
CREATE TABLE `lesson` (
`id` int(5) NOT NULL AUTO_INCREMENT,
`name` varchar(36) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
`grade` float DEFAULT 0,
`teacher` varchar(36) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT '0',
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 4 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;
INSERT INTO `lesson` VALUES (1, '大学物理', 88, '张思瑞');
INSERT INTO `lesson` VALUES (2, '高等数学', 79, '李佛');
INSERT INTO `lesson` VALUES (3, '计算机', 99, '胡晓');二、pom.xml文件添加相关依赖jar包
4.0.0
org.springframework.boot
spring-boot-starter-parent
2.3.0.RELEASE
com.test
moredb
0.0.1-SNAPSHOT
moredb
Demo project for Spring Boot
1.8
org.springframework.boot
spring-boot-starter-web
org.mybatis.spring.boot
mybatis-spring-boot-starter
2.1.3
mysql
mysql-connector-java
runtime
org.springframework.boot
spring-boot-maven-plugin
三、application.properties文件配置两个数据库信息
server.port=9090
server.tomcat.uri-encoding=UTF-8
spring.application.name=spring+mybatis整合多数据源
#主数据源
spring.datasource.first.url=jdbc:mysql://127.0.0.1:3306/test1?useUnicode=true&characterEncoding=utf8&serverTimezone=CTT
spring.datasource.first.username=admin
spring.datasource.first.password=admin123
spring.datasource.first.driver-class-name=com.mysql.cj.jdbc.Driver
#从数据源
spring.datasource.second.url=jdbc:mysql://127.0.0.1:3306/test2?useUnicode=true&characterEncoding=utf8&serverTimezone=CTT
spring.datasource.second.username=admin
spring.datasource.second.password=admin123
spring.datasource.second.driver-class-name=com.mysql.cj.jdbc.Driver
#开启sql语句控制台显示
logging.level.com.test.moredb.dao=debug四、配置启动类
package com.test.moredb;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class MoredbApplication {
public static void main(String[] args) {
SpringApplication.run(MoredbApplication.class, args);
}
}
说明：SpringBoot会自动根据依赖来自动配置，但是我们的数据源配置被我们自己自定义配置了，此时SpringBoot 无法完成自动化配置，因此就会报错，所以此处我们需要排除 DataSourceAutoConfiguration 的自动配置。
五、添加配置参数类
package com.test.moredb.datasource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
@Component(value = "firstProperties")
@ConfigurationProperties(prefix = "spring.datasource.first")
public class FirstProperties {
private String url;
private String username;
private String password;
private String driverClassName;
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getDriverClassName() {
return driverClassName;
}
public void setDriverClassName(String driverClassName) {
this.driverClassName = driverClassName;
}
}
package com.test.moredb.datasource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
@Component(value = "secondProperties")
@ConfigurationProperties(prefix = "spring.datasource.second")
public class SecondProperties {
private String url;
private String username;
private String password;
private String driverClassName;
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getDriverClassName() {
return driverClassName;
}
public void setDriverClassName(String driverClassName) {
this.driverClassName = driverClassName;
}
}
说明：@ConfigurationProperties 注解表示使用不同的前缀的配置参数注入到实体类中，即 application.properties 文件中的参数信息转化为实力类的属性。
六、创建 mybatis 配置类
package com.test.moredb.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.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 javax.annotation.Resource;
import javax.sql.DataSource;
@Configuration
@MapperScan(basePackages = "com.test.moredb.dao.student", sqlSessionFactoryRef = "firstSqlSessionFactory")
public class FirstDataSourceConfig {
@Resource(name = "firstProperties")
private FirstProperties config;
@Bean(name = "dsOne")
@Primary
public DataSource dsOne() {
System.out.println("************************>" + config.getUrl());
return DataSourceBuilder.create().url(config.getUrl()).username(config.getUsername()).password(config.getPassword()).driverClassName(config.getDriverClassName()).build();
}
@Bean(name = "firstSqlSessionFactory")
@Primary
public SqlSessionFactory firstSqlSessionFactory(@Qualifier(value = "dsOne") DataSource dataSource) throws Exception {
SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
bean.setDataSource(dataSource);
bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml"));
return bean.getObject();
}
@Bean(name = "firstSqlSessionTemplate")
@Primary
public SqlSessionTemplate firstSqlSessionTemplate(@Qualifier(value = "firstSqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
return new SqlSessionTemplate(sqlSessionFactory);
}
}
package com.test.moredb.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.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import javax.annotation.Resource;
import javax.sql.DataSource;
@Configuration
@MapperScan(basePackages = "com.test.moredb.dao.lesson", sqlSessionFactoryRef = "secondSqlSessionFactory")
public class SecondDataSourceConfig {
@Resource(name = "secondProperties")
private SecondProperties config;
@Bean(name = "dsTwo")
public DataSource dsTwo() {
System.out.println("------------------------>" + config.getUrl());
return DataSourceBuilder.create().url(config.getUrl()).username(config.getUsername()).password(config.getPassword()).driverClassName(config.getDriverClassName()).build();
}
@Bean(name = "secondSqlSessionFactory")
public SqlSessionFactory firstSqlSessionFactory(@Qualifier(value = "dsTwo") DataSource dataSource) throws Exception {
SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
bean.setDataSource(dataSource);
bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/*.xml"));
return bean.getObject();
}
@Bean(name = "SecondSqlSessionTemplate")
public SqlSessionTemplate SecondSqlSessionTemplate(@Qualifier(value = "secondSqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
return new SqlSessionTemplate(sqlSessionFactory);
}
}
说明：
1、@Configuration 表示这个类为配置类；
2、@MapperScan 通过 “basePackages” 属性设置 Mapper 接口的所在位置，通过 “sqlSessionFactoryRef” 属性指定 sqlSessionFactory 实例；
3、SqlSessionFactoryBean.setMapperLocations(Resource... mapperLocations) 方法表示指定mybatis映射的sql文件的xml文件的位置，这个必须指定，不然会报 no statement 错误，我就因为这个问题被折腾了一小时...
4、@Qualifier 注解表示按照实例名去查找相应的实例注入，结合 @Autowired 注解，效果等同于 @Resource 注解，即 @Autowired + @Qualifier = @Resource；
5、配置多个数据源时，其中一个配置类必须加 @Primary 注解，表示将此数据源配置视为主数据源（即默认数据源），否则会报错；
6、如果是主从复制- -读写分离：比如test1中负责增删改，test2中负责查询。但是需要注意的是负责增删改的数据库必须是主库（master）。
七、创建表结构实体类
package com.test.moredb.entity;
import org.springframework.stereotype.Component;
import java.io.Serializable;
@Component
public class Student implements Serializable {
private Integer id;
private String name;
private Integer age;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}
package com.test.moredb.entity;
import org.springframework.stereotype.Component;
import java.io.Serializable;
@Component
public class Lesson implements Serializable {
private Integer id;
private String name;
private float grade;
private String teacher;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public float getGrade() {
return grade;
}
public void setGrade(float grade) {
this.grade = grade;
}
public String getTeacher() {
return teacher;
}
public void setTeacher(String teacher) {
this.teacher = teacher;
}
}
八、创建SQL接口
package com.test.moredb.dao.student;
import com.test.moredb.entity.Student;
import java.util.List;
public interface StudentMapper {
List getList();
}
package com.test.moredb.dao.lesson;
import com.test.moredb.entity.Lesson;
import java.util.List;
public interface LessonMapper {
List getList();
}
说明：
1、前面 mybais 配置类我们已经添加 @MapperScan 注解，这个注解会扫描指定路径下的所有接口，因此这里无需再添加 @Mapper 注解；
2、两个接口类必须放在两个不同的包下，否则会报错，因为这个被整了一个多小时...
九、创建SQL映射xml文件
在前面配置类中我们已经指定xml的文件路径位置（“classpath:mapper/*.xml”），因此我们在 resources 目录下创建 mapper 目录，并创建两个xml文件。
十、创建controller
package com.test.moredb.controller;
import com.test.moredb.dao.lesson.LessonMapper;
import com.test.moredb.dao.student.StudentMapper;
import com.test.moredb.entity.Lesson;
import com.test.moredb.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RestController
public class DbController {
@Autowired
private StudentMapper studentMapper;
@Autowired
private LessonMapper lessonMapper;
@GetMapping("/student")
public List queryForStudent() {
return studentMapper.getList();
}
@GetMapping("/lesson")
public List queryForLesson() {
return lessonMapper.getList();
}
@GetMapping("/test")
public String test() {
return "页面数据测试！";
}
}
十一、测试运行
此时，所有配置均已完成，整个结构如下图：
启动项目，测试结果：
不同数据库的数据显示出来，说明多数据源切换成功。