SpringBoot_第七章(读写分离)

这里列举了三种读写分离实现方案,分别是如下三种

1：MybatisPlus（读写分离）

1.1：首先创建三个数据库1主2从

表名是user表

1.2：代码实例

1：导入pom


        <!--MybatisPlus的jar 3.0基于jdk8-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.3.1</version>
        </dependency>

        <!-- mybatisPlus多数据源依赖  实现读写分离-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>3.6.1</version>
        </dependency>

        <!-- mysql的依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.33</version>
        </dependency>

        <!--直接使用druid的starter 连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.2.16</version>
        </dependency>

2：配置spring的主从

server:
  port: 8082

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 #严格匹配数据源,默认false. true未匹配到指定数据源时抛异常,false使用默认数据源
      datasource:
        master:
          url: jdbc:mysql://localhost:3306/W1?useUnicode=true&characterEncoding=utf-8&useSSL=false
          username: root
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver
          type: com.alibaba.druid.pool.DruidDataSource #配置德鲁伊数据源
          druid:
            initial-size: 10 #连接池初始化大小
            min-idle: 10 #最小空闲连接数
            max-active: 20 #最大连接数

        slave_1:
          url: jdbc:mysql://localhost:3306/W1R1?useUnicode=true&characterEncoding=utf-8&useSSL=false
          username: root
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver
          type: com.alibaba.druid.pool.DruidDataSource #配置德鲁伊数据源
          druid:
            initial-size: 10 #连接池初始化大小
            min-idle: 10 #最小空闲连接数
            max-active: 20 #最大连接数
        slave_2:
          url: jdbc:mysql://localhost:3306/W1R2?useUnicode=true&characterEncoding=utf-8&useSSL=false
          username: root
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver
          type: com.alibaba.druid.pool.DruidDataSource #配置德鲁伊数据源
          druid:
            initial-size: 10 #连接池初始化大小
            min-idle: 10 #最小空闲连接数
            max-active: 20 #最大连接数


        #......省略
        #以上会配置一个默认库master，一个组slave下有两个子库slave_1,slave_2

3：代码实例 @DS("slave") 注解用来切换数据源

/**
* @description 针对表【User】的数据库操作Service实现
* @createDate 2023-11-01 17:17:57
*/
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService{


    @Resource
    UserMapper userMapper;
    
    //多个从库 负载均衡轮训查询 也可以注解到类上
    //@DS("slave")
    @DS("slave")
    public User selectRW_S(Integer id) {
        return userMapper.selectById(id);
    }
    //主库查询数据
    //@DS("master")
    @DS("master")
    public User selectRW_M(Integer id) {
        return userMapper.selectById(id);
    }

    //无注解，不指定数据, 默认查询主库
    @Override
    public User selectRW(Integer id) {
        return userMapper.selectById(id);
    }
}

controller代码根据请求不同访问不同的数据源

@RestController
public class UserControllerRW {

    @Resource
    UserServiceImpl userService;

    //查询主库 @DS("master")
    @GetMapping(value = "selectRW1")
    public User selectRW_M(@RequestParam(name = "id",required = true) Integer id){
        User user = userService.selectRW_M(id);
        System.out.println(user);
        return user;
    }

    //查询从库 @DS("slave") 轮训查询
    @GetMapping(value = "selectRW2")
    public User selectRW_S(@RequestParam(name = "id",required = true) Integer id){
        User user = userService.selectRW_S(id);
        System.out.println(user);
        return user;
    }

    //无注解，不指定数据, 默认查询主库
    @GetMapping(value = "selectRW3")
    public User selectRW(@RequestParam(name = "id",required = true) Integer id){
        User user = userService.selectRW(id);
        System.out.println(user);
        return user;
    }
}

查询结果截图