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Mybatis注解实现多数据源读写分离详解

作者：hy_xiaobin　　发布时间：2021-12-15 21:44:16　

标签：mybatis,多数据源,注解

首先需要建立两个库进行测试，我这里使用的是master_test和slave_test两个库，两张库都有一张同样的表（偷懒，喜喜），表结构

表名 t_user

| 字段名 | 类型 | 备注 |
| :------: | :------: | :------: |
| id | int | 主键自增ID |
| name | varchar | 名称 |

表中分别添加两条不同数据，方便测试

主数据库记录name为xiaobin，从库为xiaoliu

开始使用Springboot 整合mybatis，首先引入pom文件

<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.4.RELEASE</version>
</parent>
<groupId>com.xiaobin</groupId>
<artifactId>mysql_master_slave</artifactId>
<version>1.0-SNAPSHOT</version>

<properties>
<java.version>1.8</java.version>
<lombok.version>1.18.6</lombok.version>
<mybatis.version>1.3.2</mybatis.version>
<lombox.version>1.18.6</lombox.version>
</properties>

<dependencies>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>

<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombox.version}</version>
</dependency>

<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>${mybatis.version}</version>
</dependency>

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.10</version>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>

</dependencies>
</project>

动态数据源配置

这里使用的数据源为druid，实现数据源之间的切换用@DataSource自定义注解，配置Aop进行切换

application.yml 配置文件

spring:
datasource:
type: com.alibaba.druid.pool.DruidDataSource
druid:
xiaobin-master: # 主数据源
driverClassName: com.mysql.jdbc.Driver
username: root
password: root
url: jdbc:mysql://localhost:3306/master_test?serverTimezone=GMT％2B8&useUnicode=true&characterEncoding=utf8
xiaobin-slave: # 从数据源
driverClassName: com.mysql.jdbc.Driver
username: root
password: root
url: jdbc:mysql://localhost:3306/slave_test?serverTimezone=GMT％2B8&useUnicode=true&characterEncoding=utf8
mybatis:
mapper-locations: classpath:mapper/*.xml

多数据源配置类

package com.xiaobin.config;

import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.stereotype.Component;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;

/**
* 创建时间： 2019/9/22 11:42
* 备注：多数据源配置信息
* 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事
**/

@Configuration
@Component
public class DynamicDataSourceConfig {

@Bean
@ConfigurationProperties("spring.datasource.druid.xiaobin-master")
public DataSource xiaobinMasterDataSource(){
return DruidDataSourceBuilder.create().build();
}

@Bean
@ConfigurationProperties("spring.datasource.druid.xiaobin-slave")
public DataSource xiaobinSlaveDataSource(){
return DruidDataSourceBuilder.create().build();
}

@Bean
@Primary
public DynamicDataSource dataSource(DataSource xiaobinMasterDataSource, DataSource xiaobinSlaveDataSource) {
Map<Object, Object> targetDataSources = new HashMap<>();
targetDataSources.put("xiaobin-master",xiaobinMasterDataSource);
targetDataSources.put("xiaobin-slave", xiaobinSlaveDataSource);
return new DynamicDataSource(xiaobinMasterDataSource, targetDataSources);
}

}

动态数据源切换类

package com.xiaobin.config;

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import org.springframework.lang.Nullable;

import javax.sql.DataSource;
import java.util.Map;

/**
* 创建时间： 2019/9/22 11:51
* 备注：动态数据源
* 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事
**/

public class DynamicDataSource extends AbstractRoutingDataSource {

private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

public DynamicDataSource(DataSource defaultTargetDataSource, Map<Object, Object> targetDataSources) {
super.setDefaultTargetDataSource(defaultTargetDataSource);
super.setTargetDataSources(targetDataSources);
super.afterPropertiesSet();
}

@Override
protected Object determineCurrentLookupKey() {
return getDataSource();
}

public static void setDataSource(String dataSource) {
contextHolder.set(dataSource);
}

public static String getDataSource() {
return contextHolder.get();
}

public static void clearDataSource() {
contextHolder.remove();
}
}

自定义@DataSource注解

在需要切换数据的Dao添加此注解

package com.xiaobin.annotation;

import java.lang.annotation.*;

/**
* 创建时间： 2019/9/22 11:53
* 备注：自定义数据源选择注解
* 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事
**/

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DataSource {
String name() default "";
}

Aop切面类配置

package com.xiaobin.aspect;

import com.xiaobin.annotation.DataSource;
import com.xiaobin.config.DynamicDataSource;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;

/**
* 创建时间： 2019/9/22 11:54
* 备注：
* 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事
**/

@Aspect
@Component
public class DataSourceAspect {

@Pointcut("@annotation(com.xiaobin.annotation.DataSource)")
public void dataSourcePointCut() {

}

@Around("dataSourcePointCut()")
public Object around(ProceedingJoinPoint point) throws Throwable {
MethodSignature signature = (MethodSignature) point.getSignature();
Method method = signature.getMethod();

DataSource dataSource = method.getAnnotation(DataSource.class);
if(dataSource == null){
DynamicDataSource.setDataSource("xiaobin-master");
}else {
DynamicDataSource.setDataSource(dataSource.name());
}

try {
return point.proceed();
} finally {
DynamicDataSource.clearDataSource();
}
}
}

启动配置注解信息，重要（不然运行会报错）

package com.xiaobin;

import com.xiaobin.config.DynamicDataSourceConfig;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.context.annotation.Import;

/**
* 创建时间： 2019/9/22 11:17
* 备注：
* 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事
**/

@SpringBootApplication(exclude= {DataSourceAutoConfiguration.class})
@MapperScan(basePackages = "com.xiaobin.mapper")
@Import({DynamicDataSourceConfig.class})
public class StartApp {
public static void main(String[] args) {
SpringApplication.run(StartApp.class);
}
}

测试controller

package com.xiaobin.api;

import com.xiaobin.Entity.TUser;
import com.xiaobin.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
* 创建时间： 2019/9/22 12:08
* 备注：
* 码农自学交流小群：260532022，欢迎大家的加入，分享学习是一件开心事
**/

@RestController
@RequestMapping
public class UserController {

@Autowired
private UserMapper userMapper;

@GetMapping("/{name}/list")
public List<TUser> list(@PathVariable("name")String name){
if(name.equals("master")){
return userMapper.queryAllWithMaster();
}else{
return userMapper.queryAllWithSlave();
}
}
}

效果图

更具路径传值，进行主从数据源切换

目录结构

源码地址（数据库需要自己创建）https://gitee.com/MyXiaoXiaoB...

来源：https://segmentfault.com/a/1190000020458399

投稿

Mybatis注解实现多数据源读写分离详解

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