序言
在項目中，單個數據庫承受的壓力是有限的，爲了支持業務高併發的場景，多數據源的使用已經成爲必須前提。這裏使用SpringBoot整合MyBatis實現多數據源的使用案例，案例目前就使用兩個數據庫。Springboot整合mybatis實現多數據源有兩種方式：分包和AOP。這裏使用的分包，因爲層次更加清晰。
一、項目環境說明
jdk版本爲jdk1.8.0_172;
數據庫使用的是MySQL的MariaDB;
SpringBoot版本：2.2.5.RELEASE
MyBatis版本：2.1.2
這裏說明環境是因爲不同版本對應的配置參數可能會有變化，如果出現參數配置了還出現參數配置問題，有可能就是因爲版本更新之後參數變量名有變動或者包名有變動。
二、項目搭建
2.1 初始化項目
這裏IDE使用IntelliJIdea，項目初始化表方便，File->New->New Project 選擇SpringInitializr初始化一個springboot項目。
2.2 項目目錄說明
這裏只對關鍵目錄做出說明：
config目錄：存放數據源配置類，多數據源每個數據源各單獨一個配置類。
controller目錄：存放controller，開放調用接口。
mapper目錄：在這個目錄下有對應數據源ds1、ds2的mapper接口文件。
pojo目錄：存放數據實體類。
service目錄：存放業務類。
resources目錄：存放配置文件的資源目錄，mapper下面ds1、ds2分別爲數據源1數據源2的xml文件目錄。
2.3 代碼實現
首先我們從應用配置文件application.yml開始配置，配置多數據源需要爲每個數據源的datasource連接參數做出配置.
# Spring 配置
spring:
#數據源配置
datasource:
ds1: #數據源1
jdbc-url: jdbc:mysql://127.0.0.1:3306/mytest01
username: root
password: root
driver-class-name: com.mysql.jdbc.Driver
ds2: #數據源1
jdbc-url: jdbc:mysql://127.0.0.1:3306/mytest02
username: root
password: root
driver-class-name: com.mysql.jdbc.Driver
第二步我們需要爲每個數據源配置對應的DataSource，我們把配置類放在config.datasource目錄中。
先實現ds1的配置類：
```
package com.example.multdatasource.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.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.multdatasource.mapper.ds1",sqlSessionTemplateRef = "sqlSessionTemplate1")
public class DatasourceConfig1 {
@Bean(name = "datasource1")
@Primary
@ConfigurationProperties(prefix = "spring.datasource.ds1")
public DataSource getDatasource(){
return DataSourceBuilder.create().build();
}
@Primary
@Bean(name = "sqlSessionFactory1")
public SqlSessionFactory getSqlSessionFactory1(@Qualifier("datasource1") DataSource dataSource) throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSource);
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/ds1/*.xml"));
return sqlSessionFactoryBean.getObject();
}
@Bean("dataSourceTransactionManager1")
@Primary
public DataSourceTransactionManager getDataSourceTransactionManager1(@Qualifier("datasource1") DataSource dataSource){
return new DataSourceTransactionManager(dataSource);
}
@Bean("sqlSessionTemplate1")
@Primary
public SqlSessionTemplate getSqlSessionTemplate1(@Qualifier("sqlSessionFactory1") SqlSessionFactory sqlSessionFactory){
return new SqlSessionTemplate(sqlSessionFactory);
}
}
```
然後再實現ds2的DataSource配置：
package com.example.multdatasource.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.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.multdatasource.mapper.ds2",sqlSessionTemplateRef = "sqlSessionTemplate2")
public class DatasourceConfig2 {
@Bean(name = "datasource2")
@ConfigurationProperties(prefix = "spring.datasource.ds2")
public DataSource getDatasource(){
return DataSourceBuilder.create().build();
}
@Bean(name = "sqlSessionFactory2")
public SqlSessionFactory getSqlSessionFactory2(@Qualifier("datasource2") DataSource dataSource) throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSource);
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/ds2/*.xml"));
return sqlSessionFactoryBean.getObject();
}
@Bean("dataSourceTransactionManager2")
public DataSourceTransactionManager getDataSourceTransactionManager2(@Qualifier("datasource2") DataSource dataSource){
return new DataSourceTransactionManager(dataSource);
}
@Bean("sqlSessionTemplate2")
public SqlSessionTemplate getSqlSessionTemplate2(@Qualifier("sqlSessionFactory2") SqlSessionFactory sqlSessionFactory){
return new SqlSessionTemplate(sqlSessionFactory);
}
}
ds1與ds2的數據源配置大致一樣，但是稍有差別，ds1的配置類中我們加了@Primary註解，這些註解可以讓我們默認ds1爲主數據源。配置類中我們指定數據源的mapper.xml文件路徑。
第三步我們實現業務邏輯，這裏只實現增刪操作。在MariaDB中有數據庫testdb01庫user表,testdb02庫role表。
mapper/ds1/UserMapper.xml配置
```
<?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.multdatasource.mapper.ds1.UserMapper">
<resultMap id="UserResult" type="com.example.multdatasource.pojo.User">
<result property="id" column="id" javaType="Integer" ></result>
<result property="name" column="name" javaType="String" ></result>
<result property="gender" column="gender" javaType="String" ></result>
<result property="age" column="age" javaType="Integer" ></result>
</resultMap>
<select id="selectByName" resultMap="UserResult">
SELECT * FROM USER WHERE name=#{name}
</select>
<insert id="insertUser" parameterType="com.example.multdatasource.pojo.User" >
insert into
USER(name, gender, age)
values(#{name},#{gender},#{age})
</insert>
</mapper>
```
mapper/ds1/UserMapper.java實現
```
package com.example.multdatasource.mapper.ds1;
import com.example.multdatasource.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Component;
@Mapper
@Component("userMapper")
public interface UserMapper {
User selectByName(@Param("name") String name);
int insertUser(User user);
}
```
mapper/ds2/RoleMapper.xml配置
<?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.multdatasource.mapper.ds2.RoleMapper">
<resultMap id="RoleResult" type="com.example.multdatasource.pojo.Role">
<result property="id" column="id" javaType="Integer" ></result>
<result property="name" column="name" javaType="String" ></result>
<result property="role" column="role" javaType="String" ></result>
</resultMap>
<select id="selectByName" resultMap="RoleResult">
SELECT * FROM ROLE WHERE name=#{name}
</select>
<insert id="insertRole" parameterType="com.example.multdatasource.pojo.Role" >
insert into
ROLE(name, gender)
values(#{name},#{role})
</insert>
</mapper>
mapper/ds2/RoleMapper.java實現
```
package com.example.multdatasource.mapper.ds2;
import com.example.multdatasource.pojo.Role;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Component;
@Mapper
@Component("roleMapper")
public interface RoleMapper {
Role selectByName(String name);
}
```
實現對應的service
UserService.java
```
package com.example.multdatasource.service;
import com.example.multdatasource.mapper.ds1.UserMapper;
import com.example.multdatasource.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class UserService {
@Autowired
private UserMapper userMapper;
public User selectOneUser(String name){
return userMapper.selectByName(name);
}
public int insertOne(User user){
return userMapper.insertUser(user);
}
}
```
RoleService.java
```
package com.example.multdatasource.service;
import com.example.multdatasource.mapper.ds2.RoleMapper;
import com.example.multdatasource.pojo.Role;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class RoleService {
@Autowired
private RoleMapper roleMapper;
public Role getOneByName(String name){
return roleMapper.selectByName(name);
}
}
```
實現對應的Controller
UserController.java
```
package com.example.multdatasource.controller;
import com.example.multdatasource.pojo.User;
import com.example.multdatasource.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import java.util.HashMap;
import java.util.Map;
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
@RequestMapping("/getOne")
@ResponseBody
public User getOne(@RequestBody Map<String,Object> requestBody){
String name = requestBody.get("name").toString();
System.out.println("getOne");
return userService.selectOneUser(name);
}
@RequestMapping("/addOne")
@ResponseBody
public Map<String,Object> insertOnt(@RequestBody User user){
Map<String,Object> response = new HashMap<>();
int insertCount = userService.insertOne(user);
String result = insertCount == 1 ? "success" : "failed";
response.put("result",result);
return response;
}
}
```
RoleController.java
```
package com.example.multdatasource.controller;
import com.example.multdatasource.pojo.Role;
import com.example.multdatasource.service.RoleService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import java.util.HashMap;
import java.util.Map;
@RestController
@RequestMapping("/role")
public class RoleController {
@Autowired
private RoleService roleService;
@RequestMapping("/getOne")
@ResponseBody
public Map<String,Object> getOne(@RequestBody Map<String,Object> request){
Map<String,Object> result = new HashMap<>();
String name = request.get("name").toString();
Role role = roleService.getOneByName(name);
result.put("role",role);
return result;
}
}
```
應用啓動我們就可以訪問localhost:8080/role/getOne去數據源ds2查詢role數據，訪問localhost:8080/user/addOn去數據源ds1新增一個user記錄。
項目地址：https://gitee.com/charberming/demos.git ，多數據源使用案例在 multdatasource目錄