适用于多种场景:纯粹多库、 读写分离、 一主多从、 混合模式等。
场景说明:
我们创建两个库,分别为:mybatis_plus
(以前的库不动)与mybatis_plus_1
(新建),将mybatis_plus库的product
表移动到mybatis_plus_1库,这样每个库一张表,通过一个测试用例分别获取用户数据与商品数据,如果获取到说明多库模拟成功。
创建数据库及表
创建数据库mybatis_plus_1
和表`product
CREATE DATABASE `mybatis_plus_1` /*!40100 DEFAULT CHARACTER SET utf8mb4 */;
use `mybatis_plus_1`;
CREATE TABLE t_product (
id BIGINT(20) NOT NULL COMMENT '主键ID',
name VARCHAR(30) NULL DEFAULT NULL COMMENT '商品名称',
price INT(11) DEFAULT 0 COMMENT '价格',
version INT(11) DEFAULT 0 COMMENT '乐观锁版本号',
PRIMARY KEY (id)
);
添加测试数据
INSERT INTO t_product (id, NAME, price) VALUES (1, '外星人笔记本', 100);
删除mybatis_plus
库中的product
表
use mybatis_plus;
DROP TABLE IF EXISTS t_product;
新建工程引入依赖
自行新建一个Spring Boot工程并选择MySQL驱动及Lombok依赖
引入MyBaits-Plus的依赖及多数据源的依赖
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.5.1</version>
</dependency>
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>dynamic-datasource-spring-boot-starter</artifactId>
<version>3.5.0</version>
</dependency>
编写配置文件
spring:
# 配置数据源信息
datasource:
dynamic:
# 设置默认的数据源或者数据源组,默认值即为master
primary: master
# 严格匹配数据源,默认false.true未匹配到指定数据源时抛异常,false使用默认数据源
strict: false
datasource:
master:
url: jdbc:mysql://localhost:3306/mybatis_plus?characterEncoding=utf-8&useSSL=false
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: 123456
slave_1:
url: jdbc:mysql://localhost:3306/mybatis_plus_1?characterEncoding=utf-8&useSSL=false
driver-class-name: com.mysql.cj.jdbc.Driver
username: root
password: 123456
mybatis-plus:
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
创建实体类
新建一个User
实体类(如果数据库表名有t_前缀记得配置)
@Data
@TableName("t_user")
public class User {
@TableId
private long uid;
private String username;
private Integer age;
private String email;
}
新建一个实体类Product
@Data
@TableName("t_product")
public class Product {
private Long id;
private String name;
private Integer price;
private Integer version;
}
创建Mapper及Service
新建接口UserMapper
public interface UserMapper extends BaseMapper<User> {
}
新建接口ProductMapper
public interface ProductMapper extends BaseMapper<Product> {
}
记得在启动类中添加注解@MapperScan()
@SpringBootApplication
@MapperScan("com.dawn.mybatisplus.mapper")
public class MybatisPlusDemo2Application {
public static void main(String[] args) {
SpringApplication.run(MybatisPlusDemo2Application.class, args);
}
}
新建Service接口UserService
指定操作的数据源
@DS("master") //指定操作的数据源,master为user表
public interface UserService extends IService<User> {
}
新建Service接口ProductService
指定操作的数据源
@DS("slave_1")
public interface ProductService extends IService<Product> {
}
创建实现类
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
}
@Service
public class ProductServiceImpl extends ServiceImpl<ProductMapper, Product> implements ProductService {
}
编写测试方法
@SpringBootTest
class MybatisPlusDemo2ApplicationTests {
@Resource
UserService userService;
@Resource
ProductService productService;
@Test
public void test(){
User user = userService.getById(1L);
Product product = productService.getById(1L);
System.out.println("User = " + user);
System.out.println("Product = " + product);
}
}
控制台打印查询结果