SpringBoot MySql读写分离-多数据源集成

1.业务场景

客户给了3台MySQL数据库服务器，一主二从，程序需要集成读写分离，充分提升数据处理能力
数据层使用了MyBatis-Plus，它有一个多数据源的中间件 dynamic-datasource-spring-boot-starter
参考：MyBatis-Plus

2.MySql主从

一主二从，搭建方式参考：docker搭建mysql读写分离

3.SpringBoot快速集成

• 1.新建SpringBoot项目，核心依赖

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

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<!--mybatis-->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.1.1</version>
</dependency>
<!-- 数据库连接池 -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.20</version>
</dependency>
<!-- 多数据源配置 -->
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
    <version>3.0.0</version>
</dependency>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>

        <!-- mybatis generator 自动生成代码插件 -->
        <plugin>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-maven-plugin</artifactId>
            <version>1.3.5</version>
            <configuration>
                <configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
                <overwrite>true</overwrite>
                <verbose>true</verbose>
            </configuration>
        </plugin>
    </plugins>
</build>

• 2.创建数据库表
• 3.使用 mybatis-generator-maven-plugin 插件连接数据，生成对应的实体类，Mapper接口和Mapper.xml文件，可参考：Mybatis持久层框架
• 4.在application.yml中添加配置，配置好主库，从库连接地址

server:
  port: 8008
mybatis-plus:
  mapper-locations: classpath:mapping/*.xml
  type-aliases-package: com.zypcy.dynamicdatabase.entity

spring:
  datasource:
    dynamic:
      primary: master #设置默认的数据源或者数据源组,默认值即为master
      strict: false #设置严格模式,默认false不启动. 启动后在未匹配到指定数据源时候回抛出异常,不启动会使用默认数据源.
      datasource:
        master:
          url: jdbc:mysql://${egov-china.datasource.master.ip}:${egov-china.datasource.master.port}/${egov-china.datasource.master.databaseName}?characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowMultiQueries=true
          username: root
          password: 123456
          driver-class-name: com.mysql.jdbc.Driver
          druid:
            initial-size: 5
            max-active: 25
            min-idle: 5
            max-wait: 120000
            min-evictable-idle-time-millis: 30000
            max-evictable-idle-time-millis: 30000
            time-between-eviction-runs-millis: 0
            validation-query: select 1
            validation-query-timeout: -1
            test-on-borrow: false
            test-on-return: false
            test-while-idle: true
            pool-prepared-statements: true
            max-open-prepared-statements: 100
            filters: stat
            share-prepared-statements: true
        slave_1:
          url: jdbc:mysql://${egov-china.datasource.slave_1.ip}:${egov-china.datasource.slave_1.port}/${egov-china.datasource.slave_1.databaseName}?characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowMultiQueries=true
          username: root
          password: 123456
          driver-class-name: com.mysql.jdbc.Driver
          druid:
            initial-size: 5
            max-active: 25
            min-idle: 5
            max-wait: 120000
            min-evictable-idle-time-millis: 30000
            max-evictable-idle-time-millis: 30000
            time-between-eviction-runs-millis: 0
            validation-query: select 1
            validation-query-timeout: -1
            test-on-borrow: false
            test-on-return: false
            test-while-idle: true
            pool-prepared-statements: true
            max-open-prepared-statements: 100
            filters: stat
            share-prepared-statements: true
        slave_2:
          url: jdbc:mysql://${egov-china.datasource.slave_2.ip}:${egov-china.datasource.slave_2.port}/${egov-china.datasource.slave_2.databaseName}?characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowMultiQueries=true
          username: root
          password: 123456
          driver-class-name: com.mysql.jdbc.Driver
          druid:
            initial-size: 5
            max-active: 25
            min-idle: 5
            max-wait: 120000
            min-evictable-idle-time-millis: 30000
            max-evictable-idle-time-millis: 30000
            time-between-eviction-runs-millis: 0
            validation-query: select 1
            validation-query-timeout: -1
            test-on-borrow: false
            test-on-return: false
            test-while-idle: true
            pool-prepared-statements: true
            max-open-prepared-statements: 100
            filters: stat
            share-prepared-statements: true

# 自定义数据连接配置
egov-china:
  # mysql 地址配置
  datasource:
    master:
      ip: 47.106.67.247
      port: 3336
      databaseName: party
    slave_1:
      ip: 120.79.181.1
      port: 3336
      databaseName: party
    slave_2:
      ip: 120.79.181.1
      port: 3337
      databaseName: party

@MapperScan("com.zypcy.dynamicdatabase.repository")
@SpringBootApplication(exclude = DruidDataSourceAutoConfigure.class)
public class DynamicDatabaseApplication {
    public static void main(String[] args) {
        SpringApplication.run(DynamicDatabaseApplication.class, args);
    }
}

• 5.在 Mapper接口文件中，指定查询方法使用从库 ，使用 @DS 注解，这是 Dynamic-Datasource提供的，slave代表轮询slave_1 和 slave_2 ，两个从库，如果只有一个从库，可以 @DS(“slave_1”)，这样insert update delete走主库，select走从库，里面的方法名是默认生成的
  
• 6.创建好控制器、服务，进行新增和查询
• 7.启动项目，可以看的master，slave_1，slave2分别 初始化好了
  
  调用新增接口，插入多条数据，然后手动在两个从库中，修改 zhuyu ，分别为 zhuyu2 , zhuyu3
  
  多次调用查询接口，可以看到@DS注解起作用了，分别查询两个从库的数据
  
• 8.源码下载

此方式可以简单的实现多数据源读写分离控制，但是对代码侵入性高，需要在查询的方法上手动控制，而 利用 Sharding-JDBC 实现读写分离对代码侵入性低，会自动识别select或写 sql，来自动读写