Spring Boot MyBatis 数据库集群读写分离实现验证

Spring Boot实现方式

读写分离要做的事情就是对于一条SQL该选择哪个数据库去执行，至于谁来做选择数据库这件事儿，一般来讲，主要有两种实现方式，分别为：

1.使用中间件，比如Atlas，cobar，TDDL，mycat，heisenberg，Oceanus，vitess，OneProxy等

2.使用程序自己实现，利用Spring Boot提供的路由数据源以及AOP，实现起来简单快捷（本文要介绍的方法）

代码实现

1.首先配置下pom.xml

<dependencies>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

<scope>test</scope>

</dependency>

<dependency>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

<scope>runtime</scope>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-jdbc</artifactId>

</dependency>

<dependency>

<groupId>org.projectlombok</groupId>

<artifactId>lombok</artifactId>

<optional>true</optional>

</dependency>

<dependency>

<groupId>org.mybatis.spring.boot</groupId>

<artifactId>mybatis-spring-boot-starter</artifactId>

<version>2.1.0</version>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-aop</artifactId>

</dependency>

</dependencies>

2.数据源路由类功能RoutingDataSource.java

package com.example.demo.databases;

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

/**

* 数据源路由类功能

* @author fansongsong

* @since 2020-09-08

* @version 1.0

*/

public class RoutingDataSource extends AbstractRoutingDataSource {

@Override

protected Object determineCurrentLookupKey() {

return DBContext.get();

}

}

3.数据源上下文类DBContext.java

package com.example.demo.databases;

import lombok.extern.slf4j.Slf4j;

import java.util.concurrent.atomic.AtomicInteger;

/**

* 数据源上下文类

* @author fansongsong

* @since 2020-09-08

* @version 1.0

*/

@Slf4j

public class DBContext {

private static final ThreadLocal<DBTypeEnum> dbContext = new ThreadLocal<>();

private static final AtomicInteger counter = new AtomicInteger(-1);

public static void set(DBTypeEnum dbType) {

dbContext.set(dbType);

}

public static DBTypeEnum get() {

return dbContext.get();

}

public static void master() {

set(DBTypeEnum.MASTER);

log.info("切换到master库");

}

public static void slave() {

// 读库负载均衡(轮询方式)

int index = counter.getAndIncrement() % 2;

log.info("slave库访问线程数==>{}", counter.get());

if (index == 0) {

set(DBTypeEnum.SLAVE1);

log.info("切换到slave1库");

} else {

set(DBTypeEnum.SLAVE2);

log.info("切换到slave2库");

}

}

}

4.数据库枚举类DBTypeEnum.java

package com.example.demo.databases;

/**

* 数据库枚举类

* @author fansongsong

* @since 2020-09-08

* @version 1.0

*/

public enum DBTypeEnum {

MASTER, SLAVE1, SLAVE2

}

这里我们配置三个库，分别是一个写库Master，2个读库slave1,slave2

5.数据库配置类DataSourceConfig.java

package com.example.demo.databases;

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 javax.sql.DataSource;

import java.util.HashMap;

import java.util.Map;

/**

* 数据库配置类

* @author fansongsong

* @since 2020-09-08

* @version 1.0

*/

@Configuration

public class DataSourceConfigs {

@Bean

@ConfigurationProperties("spring.datasource.master")

public DataSource masterDataSource() {

return DataSourceBuilder.create().build();

}

@Bean

@ConfigurationProperties("spring.datasource.slave1")

public DataSource slave1DataSource() {

return DataSourceBuilder.create().build();

}

@Bean

@ConfigurationProperties("spring.datasource.slave2")

public DataSource slave2DataSource() {

return DataSourceBuilder.create().build();

}

@Bean

public DataSource myRoutingDataSource(@Qualifier("masterDataSource") DataSource masterDataSource,

@Qualifier("slave1DataSource") DataSource slave1DataSource,

@Qualifier("slave2DataSource") DataSource slave2DataSource) {

Map<Object, Object> targetDataSources = new HashMap<>();

targetDataSources.put(DBTypeEnum.MASTER, masterDataSource);

targetDataSources.put(DBTypeEnum.SLAVE1, slave1DataSource);

targetDataSources.put(DBTypeEnum.SLAVE2, slave2DataSource);

RoutingDataSource routingDataSource = new RoutingDataSource();

routingDataSource.setDefaultTargetDataSource(masterDataSource);

routingDataSource.setTargetDataSources(targetDataSources);

return routingDataSource;

}

}

6.mybatis配置类DataSourceConfigs.java

package com.example.demo.databases;

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 javax.sql.DataSource;

import java.util.HashMap;

import java.util.Map;

/**

* 数据库配置类

* @author fansongsong

* @since 2020-09-08

* @version 1.0

*/

@Configuration

public class DataSourceConfigs {

@Bean

@ConfigurationProperties("spring.datasource.master")

public DataSource masterDataSource() {

return DataSourceBuilder.create().build();

}

@Bean

@ConfigurationProperties("spring.datasource.slave1")

public DataSource slave1DataSource() {

return DataSourceBuilder.create().build();

}

@Bean

@ConfigurationProperties("spring.datasource.slave2")

public DataSource slave2DataSource() {

return DataSourceBuilder.create().build();

}

@Bean

public DataSource myRoutingDataSource(@Qualifier("masterDataSource") DataSource masterDataSource,

@Qualifier("slave1DataSource") DataSource slave1DataSource,

@Qualifier("slave2DataSource") DataSource slave2DataSource) {

Map<Object, Object> targetDataSources = new HashMap<>();

targetDataSources.put(DBTypeEnum.MASTER, masterDataSource);

targetDataSources.put(DBTypeEnum.SLAVE1, slave1DataSource);

targetDataSources.put(DBTypeEnum.SLAVE2, slave2DataSource);

RoutingDataSource routingDataSource = new RoutingDataSource();

routingDataSource.setDefaultTargetDataSource(masterDataSource);

routingDataSource.setTargetDataSources(targetDataSources);

return routingDataSource;

}

}

7.切面类DataSourceAop.java

package com.example.demo.databases;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.Before;

import org.aspectj.lang.annotation.Pointcut;

import org.springframework.stereotype.Component;

/**

* 切面类DataSourceAop

* @author fansongsong

* @since 2020-09-08

* @version 1.0

*/

@Aspect

@Component

public class DataSourceAop {

@Pointcut("@annotation(com.example.demo.databases.Master) " +

"|| execution(* com.example.demo.*.service..*.insert*(..)) " +

"|| execution(* com.example.demo.*.service..*.create*(..)) " +

"|| execution(* com.example.demo.*.service..*.save*(..)) " +

"|| execution(* com.example.demo.*.service..*.add*(..)) " +

"|| execution(* com.example.demo.*.service..*.update*(..)) " +

"|| execution(* com.example.demo.*.service..*.edit*(..)) " +

"|| execution(* com.example.demo.*.service..*.delete*(..)) " +

"|| execution(* com.example.demo.*.service..*.remove*(..))")

public void writePointcut() {

}

@Pointcut("!@annotation(com.example.demo.databases.Master) " +

"&& (execution(* com.example.demo.*.service..*.select*(..)) " +

"|| execution(* com.example.demo.*.service..*.list*(..))" +

"|| execution(* com.example.demo.*.service..*.count*(..))" +

"|| execution(* com.example.demo.*.service..*.get*(..)))"

)

public void readPointcut() {

}

@Before("writePointcut()")

public void write() {

DBContext.master();

}

@Before("readPointcut()")

public void read() {

DBContext.slave();

}

}

8.注解类Master.java

package com.example.demo.databases;

/**

* 注解类Master 主库，可读写

* @author fansongsong

* @since 2020-09-08

* @version 1.0

*/

public @interface Master {

}

9，验证

请求查询接口

指定数据源写库（查询默认读库，可以通过@Master注解加到方法上手动指定写库）

请求新增方法

请求批量新增用户接口

查看数据源切换到主库

验证数据主从同步成功