springboot + mybatis + druid + 多数据源的问题详解

时间：2021-07-24 22:44:29

一. 简介

           俩个数据库db1,db2， db1数据库的mapper.xml和db2数据库的mapper.xml分别放到不同的目录下, 通过给不同的目录配置不同的数据源，并分别监控各自的事务。

已有新版方案： Mybatis Plus整合多数据源和读写分离，请使用新版；

 二. sql脚本

           db1数据库的user表：

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CREATE TABLE `user` (
  `id` int(11) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

           db2数据库的role表：

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CREATE TABLE `role` (
  `id` int(11) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

三. 工程搭建

3.1 目录结构图

springboot + mybatis + druid + 多数据源的问题详解

3.2 pom.xml文件

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<?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.example</groupId>
    <artifactId>datasources</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
 
    <name>datasources</name>
    <description>Demo project for Spring Boot</description>
 
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
        <relativePath/>
    </parent>
 
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</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>1.3.2</version>
        </dependency>
 
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
 
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.4</version>
        </dependency>
 
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-joda</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-parameter-names</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
 
        <!-- 分页插件 -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.5</version>
        </dependency>
 
        <!-- alibaba的druid数据库连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.9</version>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
 
        <!-- atomikos transaction management -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jta-atomikos</artifactId>
        </dependency>
 
        <!-- swagger -->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.6.1</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.6.1</version>
        </dependency>
        <!-- swagger -->
 
 
    </dependencies>
 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
 
</project>

3.3 application.yml

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server:
  port: 8080
 
 
spring:
  datasource:
    db1:
      driverClassName: com.mysql.jdbc.Driver
      username: 用户名
      password: 密码
      # spring2.0此处为jdbc-url
      jdbc-url: jdbc:mysql://IP:3306/db1?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true
      type: com.alibaba.druid.pool.DruidDataSource
    db2:
      driverClassName: com.mysql.jdbc.Driver
      username: 用户名
      password: 密码
      # spring2.0此处为jdbc-url
      jdbc-url: jdbc:mysql://IP:3306/db2?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true
      type: com.alibaba.druid.pool.DruidDataSource

 3.4 数据源配置类

3.4.1 db1数据库的数据源 （主数据源@Primary）

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package com.example.datasources.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.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.example.datasources.mapper.db1", sqlSessionTemplateRef = "db1SqlSessionTemplate")
public class DataSource1Config {
 
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.db1")
    @Primary
    public DataSource db1DataSource() {
        return DataSourceBuilder.create().build();
    }
 
    @Bean
    @Primary
    public SqlSessionFactory db1SqlSessionFactory(@Qualifier("db1DataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:com/example/datasources/mapper/db1/*.xml"));
        return bean.getObject();
    }
 
    @Bean
    @Primary
    public DataSourceTransactionManager db1TransactionManager(@Qualifier("db1DataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
 
    @Bean
    @Primary
    public SqlSessionTemplate db1SqlSessionTemplate(@Qualifier("db1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
 
}

3.4.2 db2数据库的数据源

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package com.example.datasources.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.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.example.datasources.mapper.db2", sqlSessionTemplateRef = "db2SqlSessionTemplate")
public class DataSource2Config {
 
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.db2")
    public DataSource db2DataSource() {
        return DataSourceBuilder.create().build();
    }
 
    @Bean
    public SqlSessionFactory db2SqlSessionFactory(@Qualifier("db2DataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:com/example/datasources/mapper/db2/*.xml"));
        return bean.getObject();
    }
 
    @Bean
    public DataSourceTransactionManager db2TransactionManager(@Qualifier("db2DataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
 
    @Bean
    public SqlSessionTemplate db2SqlSessionTemplate(@Qualifier("db2SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
 
 
}

3.5 Controller

3.5.1 db1的UserController

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package com.example.datasources.controller;
 
import com.example.datasources.entity.db1.User;
import com.example.datasources.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
 
import java.util.List;
 
@RestController
@RequestMapping("/user")
public class UserController {
 
    @Autowired
    private UserService userService;
 
    @GetMapping("/select/list")
    public List<User> selectUserList() {
        return this.userService.selectUserList();
    }
 
    @GetMapping("/save")
    public void saveUser(User user) {
        this.userService.saveUser(user);
    }
 
 
}

3.5.2 db2的RoleController

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package com.example.datasources.controller;
 
import com.example.datasources.entity.db2.Role;
import com.example.datasources.service.RoleService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
import java.util.List;
 
@RestController
@RequestMapping("/role")
public class RoleController {
 
    @Autowired
    private RoleService roleService;
 
    @GetMapping("/select/list")
    public List<Role> selectRoleList() {
        return this.roleService.selectRoleList();
    }
 
    @GetMapping("/save")
    public void saveRole(Role role) {
        this.roleService.saveRole(role);
    }
 
 
}

3.6 Service

3.6.1 db1的UserService

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package com.example.datasources.service;
 
import com.example.datasources.entity.db1.User;
 
import java.util.List;
 
public interface UserService {
 
    List<User> selectUserList();
 
    void saveUser(User user);
 
}

3.6.2 db2的RoleService

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package com.example.datasources.service;
 
import com.example.datasources.entity.db2.Role;
 
import java.util.List;
 
public interface RoleService {
 
    List<Role> selectRoleList();
 
    void saveRole(Role role);
 
}

3.7 serviceImpl

3.7.1 db1的UserServiceImpl

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package com.example.datasources.service.impl;
 
import com.example.datasources.entity.db1.User;
import com.example.datasources.mapper.db1.UserMapper;
import com.example.datasources.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
 
import java.util.List;
 
@Service
public class UserServiceImpl implements UserService {
 
    @Autowired
    private UserMapper userMapper;
 
    @Override
    public List<User> selectUserList() {
        return this.userMapper.selectUserList();
    }
 
    @Transactional
    @Override
    public void saveUser(User user) {
        this.userMapper.saveUser(user);
//        throw new RuntimeException();
    }
}

3.7.2 db2的RoleServiceImpl

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package com.example.datasources.service.impl;
 
import com.example.datasources.entity.db2.Role;
import com.example.datasources.mapper.db2.RoleMapper;
import com.example.datasources.service.RoleService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
 
import java.util.List;
 
@Service
public class RoleServiceImpl implements RoleService {
 
    @Autowired
    private RoleMapper roleMapper;
 
    @Override
    public List<Role> selectRoleList() {
        return this.roleMapper.selectRoleList();
    }
 
    // 注：不是主数据源必须要声明其数据源，否则事务不起作用
    @Transactional(value = "db2TransactionManager")
    @Override
    public void saveRole(Role role) {
        this.roleMapper.saveRole(role);
//        throw new RuntimeException();
    }
}

3.8 mapper

3.8.1 db1的UserMapper

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package com.example.datasources.mapper.db1;
 
import com.example.datasources.entity.db1.User;
 
import java.util.List;
 
public interface UserMapper {
 
    List<User> selectUserList();
 
    void saveUser(User user);
 
}

3.8.2 db2的RoleMapper

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package com.example.datasources.mapper.db2;
 
import com.example.datasources.entity.db2.Role;
 
import java.util.List;
 
public interface RoleMapper {
 
    List<Role> selectRoleList();
 
    void saveRole(Role role);
}

3.9 mapper.xml

3.9.1 db1的UserMapper.xml

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<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.example.datasources.mapper.db1.UserMapper" >
 
    <resultMap id="BaseResultMap" type="com.example.datasources.entity.db1.User" >
        <id column="id" property="id" jdbcType="BIGINT" />
        <result column="name" property="name" jdbcType="VARCHAR" />
    </resultMap>
 
 
    <sql id="Base_Column_List" >
        id, `name`
    </sql>
 
 
    <select id="selectUserList" resultMap="BaseResultMap"  >
        SELECT
          <include refid="Base_Column_List" />
        FROM `user`
    </select>
 
 
    <insert id="saveUser" parameterType="com.example.datasources.entity.db1.User">
        INSERT INTO `user`
           (id, `name`)
        VALUES
           ( #{id}, #{name} )
    </insert>
 
</mapper>

3.9.2 db2的RoleMapper.xml

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<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.example.datasources.mapper.db2.RoleMapper" >
 
    <resultMap id="BaseResultMap" type="com.example.datasources.entity.db2.Role" >
        <id column="id" property="id" jdbcType="BIGINT" />
        <result column="name" property="name" jdbcType="VARCHAR" />
    </resultMap>
 
    <sql id="Base_Column_List" >
        id, name
    </sql>
 
    <select id="selectRoleList" resultMap="BaseResultMap"  >
        SELECT
          <include refid="Base_Column_List" />
        FROM
          role
    </select>
 
 
    <insert id="saveRole" parameterType="com.example.datasources.entity.db2.Role">
        INSERT INTO `role`
           (id, `name`)
        VALUES
           ( #{id}, #{name} )
    </insert>
 
</mapper>

3.10 entity

3.10.1 db1的User

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package com.example.datasources.entity.db1;
 
public class User {
 
    private Integer id;
    private String name;
 
    public User() {
    }
 
    public User(Integer id, String name) {
        this.id = id;
        this.name = name;
    }
 
    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;
    }
}

3.10.2 db2的Role 

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package com.example.datasources.entity.db2;
 
public class Role {
 
    private Integer id;
    private String name;
 
    public Role() {
    }
 
    public Role(Integer id, String name) {
        this.id = id;
        this.name = name;
    }
 
    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;
    }
 
}

3.11  启动类

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package com.example.datasources;
 
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
 
@SpringBootApplication
public class DatasourcesApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(DatasourcesApplication.class, args);
    }
}

四. 测试

      可以直接在浏览器测试，测试事务的时候可以将异常打开。

            需要注意的是： 非主数据源必须要在@Transactional注解中指定数据源，否则事务不起作用。主数据库不需要。 

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原文链接：https://blog.csdn.net/qq_35206261/article/details/81778224

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