#### Mybatis多数据源读写分离（注解实现）
——
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
“`
4.0.0
org.springframework.boot
spring-boot-starter-parent
2.1.4.RELEASE
com.xiaobin
mysql_master_slave
1.0-SNAPSHOT
1.8
1.18.6
1.3.2
1.18.6
org.springframework.boot
spring-boot-starter-web
org.projectlombok
lombok
${lombok.version}
org.springframework.boot
spring-boot-starter-test
org.projectlombok
lombok
${lombox.version}
org.mybatis.spring.boot
mybatis-spring-boot-starter
${mybatis.version}
mysql
mysql-connector-java
org.springframework.boot
spring-boot-starter-jdbc
com.alibaba
druid-spring-boot-starter
1.1.10
org.springframework.boot
spring-boot-starter-aop
“`
#### 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 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 contextHolder = new ThreadLocal();
public DynamicDataSource(DataSource defaultTargetDataSource, Map 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 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/MyXiaoXiaoBin/learning-to-share/tree/master/mysql_master_slave
###### 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
