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springboot实战代码系列之【集成mybatis-plus和druid实现多数据源切换】
为什么要写本文？
- 官方文档给的不够详细，下面是一个能即读即用的版本
- 主要也方便自己以后参考代码，不再重复查找
本文使用的springboot版本：2.2.6.RELEASE
添加依赖
查看一下最新版本的插件：https://mvnrepository.com/artifact/com.baomidou/mybatis-plus-boot-starter
druid插件的最新版也要看看：https://mvnrepository.com/artifact/com.alibaba/druid-spring-boot-starter
不过这里，还是建议看mybatis plus所支持的druid版本。
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<!--@DS注解需要的依赖-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>dynamic-datasource-spring-boot-starter</artifactId>
<version>3.0.0</version>
</dependency>
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.3.1</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.21</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>配置文件
首先要移除Druid自动配置类：
@SpringBootApplication(exclude = DruidDataSourceAutoConfigure.class)某些springBoot的版本上面可能无法排除可用以下方式排除。
spring:
autoconfigure:
exclude: com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure原因：DruidDataSourceAutoConfigure会注入一个DataSourceWrapper，其会在原生的spring.datasource下找url,username,password等。而我们动态数据源的配置路径是变化的。
然后下面是非常简单的一个druid配置（附录有完整配置）：
spring:
datasource:
dynamic:
# 默认源
primary: druid-admin
druid:
#初始化大小,最小,最大
initial-size: 5
min-idle: 5
max-active: 20
datasource:
# 数据源1
druid-admin:
url: jdbc:mysql://IP:3306/db_admin?allowMultiQueries=true&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
username: xxx
password: xxx
driver-class-name: com.mysql.cj.jdbc.Driver
# 数据源2
druid-web:
url: jdbc:mysql://IP:3306/db_web?allowMultiQueries=true&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
username: xxx
password: xxx
driver-class-name: com.mysql.cj.jdbc.Driver代码
因为要用分页查询测试，所以加上分页插件
/**
* 分页插件,解决分页时total=0问题
*/
@Bean
public PaginationInterceptor paginationInterceptor() {
return new PaginationInterceptor();
}准备实体类
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;
@Data
@TableName("t_user")
public class User {
@TableId(type = IdType.AUTO)
private Integer id;
@TableField(value = "user_name")
private String username;
private String password;
private String email;
}
@Data
@TableName("role")
public class Role {
@TableId(type = IdType.AUTO)
private Integer id;
private String name;
}准备mapper
只需要继承BaseMapper得到常用的CRUD接口方法即可，再加上@Mapper注解标识
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.jimo.mybatisplusdruiddemo.model.User;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface UserMapper extends BaseMapper<User> {
}
@Mapper
public interface RoleMapper extends BaseMapper<Role> {
}写service层
只需继承ServiceImpl就好。
这里的@DS注解就是选择数据源的，名字与配置里的对应
import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.jimo.mybatisplusdruiddemo.mapper.UserMapper;
import com.jimo.mybatisplusdruiddemo.model.User;
import org.springframework.stereotype.Service;
@Service
@DS("druid-web")
public class UserService extends ServiceImpl<UserMapper, User> {
}
/**
* 因为默认就是druid-admin库，所以，可以省略，加上也没关系
*/
@Service
//@DS("druid-admin")
public class RoleService extends ServiceImpl<RoleMapper, Role> {
}测试
测试类非常简单，执行一个分页查询：
@SpringBootTest
class MybatisPlusDruidDemoApplicationTests {
@Autowired
private UserService userService;
@Autowired
private RoleService roleService;
@Test
void testUserService() {
final int size = 10;
final Page<User> page = userService.page(new Page<>(1, size));
assertEquals(size, page.getRecords().size());
assertTrue(page.getTotal() >= size);
}
@Test
void testRoleService() {
final int size = 1;
final Page<Role> page = roleService.page(new Page<>(1, size));
assertEquals(size, page.getRecords().size());
assertTrue(page.getTotal() >= size);
}
} 可以看到日志里数据库的初始化和销毁：
2020-04-01 10:34:20.661 INFO 15600 --- [ main] j.m.MybatisPlusDruidDemoApplicationTests : No active profile set, falling back to default profiles: default
2020-04-01 10:34:22.805 INFO 15600 --- [ main] com.alibaba.druid.pool.DruidDataSource : {dataSource-1,druid-admin} inited
2020-04-01 10:34:23.118 INFO 15600 --- [ main] com.alibaba.druid.pool.DruidDataSource : {dataSource-2,druid-web} inited
2020-04-01 10:34:23.118 INFO 15600 --- [ main] c.b.d.d.DynamicRoutingDataSource : dynamic-datasource - load a datasource named [druid-admin] success
2020-04-01 10:34:23.119 INFO 15600 --- [ main] c.b.d.d.DynamicRoutingDataSource : dynamic-datasource - load a datasource named [druid-web] success
2020-04-01 10:34:23.119 INFO 15600 --- [ main] c.b.d.d.DynamicRoutingDataSource : dynamic-datasource initial loaded [2] datasource,primary datasource named [druid-admin]
_ _ |_ _ _|_. ___ _ | _
| | |\/|_)(_| | |_\ |_)||_|_\
/ |
3.3.1
2020-04-01 10:34:24.379 INFO 15600 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'applicationTaskExecutor'
2020-04-01 10:34:24.888 INFO 15600 --- [ main] j.m.MybatisPlusDruidDemoApplicationTests : Started MybatisPlusDruidDemoApplicationTests in 4.695 seconds (JVM running for 6.375)
...
2020-04-01 10:34:56.112 INFO 15600 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor : Shutting down ExecutorService 'applicationTaskExecutor'
2020-04-01 10:34:56.113 INFO 15600 --- [extShutdownHook] c.b.d.d.DynamicRoutingDataSource : dynamic-datasource start closing ....
2020-04-01 10:34:56.116 INFO 15600 --- [extShutdownHook] com.alibaba.druid.pool.DruidDataSource : {dataSource-1} closing ...
2020-04-01 10:34:56.126 INFO 15600 --- [extShutdownHook] com.alibaba.druid.pool.DruidDataSource : {dataSource-1} closed
2020-04-01 10:34:56.126 INFO 15600 --- [extShutdownHook] com.alibaba.druid.pool.DruidDataSource : {dataSource-2} closing ...
2020-04-01 10:34:56.130 INFO 15600 --- [extShutdownHook] com.alibaba.druid.pool.DruidDataSource : {dataSource-2} closed
2020-04-01 10:34:56.130 INFO 15600 --- [extShutdownHook] c.b.d.d.DynamicRoutingDataSource : dynamic-datasource all closed success,bye总结
重点强调
@DS("druid-web")注解用来选择数据源，是可以用在mapper层的
@Mapper
@DS("druid-web")
public interface UserMapper extends BaseMapper<User> {
}就像有时候偷懒，不想写service层，也可以在mapper就实现多数据源切换：
@Autowired
private UserMapper userMapper;
@Test
void testUserMapper() {
final int size = 10;
final Page<User> page = userMapper.selectPage(new Page<>(1, size), null);
assertEquals(size, page.getRecords().size());
assertTrue(page.getTotal() >= size);
}附录
druid的完整配置：
spring:
datasource:
dynamic:
primary: druid-admin
druid:
#初始化大小,最小,最大
initial-size: 5
min-idle: 5
max-active: 20
#配置获取连接等待超时的时间
max-wait: 60000
#配置间隔多久才进行一次检测,检测需要关闭的空闲连接,单位是毫秒
time-between-eviction-runs-millis: 60000
#配置一个连接在池中最小生存的时间,单位是毫秒
min-evictable-idle-time-millis: 300000
validation-query: SELECT 1 FROM DUAL
test-while-idle: true
test-on-borrow: false
test-on-return: false
#打开PSCache,并且指定每个连接上PSCache的大小
pool-prepared-statements: true
max-pool-prepared-statement-per-connection-size: 20
#配置监控统计拦截的filters,去掉后监控界面sql无法统计,'wall'用于防火墙
filters: stat,wall # 注意这个值和druid原生不一致，默认启动了stat,wall
filter:
log4j:
enabled: true
wall:
config:
# 允许多个语句一起执行
multi-statement-allow: true
enabled: true
db-type: mysql
stat:
enabled: true
db-type: mysql
datasource:
# 数据源1
druid-admin:
url: jdbc:mysql://IP:3306/db_admin?allowMultiQueries=true&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
username: xxx
password: xxx
driver-class-name: com.mysql.cj.jdbc.Driver
# 数据源2
druid-web:
url: jdbc:mysql://IP:3306/db_web?allowMultiQueries=true&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
username: xxx
password: xxx
driver-class-name: com.mysql.cj.jdbc.Driver
