Springcloud Alibaba使用Canal将Mysql数据实时同步到Redis保证缓存的一致性

1. 背景

canal [kə'næl] ，译意为水道/管道/沟渠，主要用途是基于 MySQL 数据库增量日志解析，提供增量数据订阅和消费。其诞生的背景是早期阿里巴巴因为杭州和美国双机房部署，存在跨机房同步的业务需求，实现方式主要是基于业务 trigger 获取增量变更。从 2010 年开始，业务逐步尝试数据库日志解析获取增量变更进行同步，由此衍生出了大量的数据库增量订阅和消费业务。所以其核心功能如下：

• 数据实时备份
• 异构数据源(elasticsearch、Hbase)与数据库数据增量同步
• 业务缓存cache 刷新，保证缓存一致性
• 带业务逻辑的增量数据处理，如监听某个数据的变化做一定的逻辑处理

canal是借助于MySQL主从复制原理实现

• master将改变记录到二进制日志(binary log)中（这些记录叫做二进制日志事件，binary log events，可以通过show binlog events进行查看）；
• slave将master的binary log events拷贝到它的中继日志(relay log)；
• slave重做中继日志中的事件，将改变反映它自己的数据。

canal的工作原理：

• canal模拟mysql slave的交互协议，伪装自己为mysql slave，向mysql master发送dump协议
• mysql master收到dump请求，开始推送binary log给slave(也就是canal)
• canal解析binary log对象(原始为byte流)

2. Windows系统安装canal

Github下载链接：Releases · alibaba/canal · GitHub

解压

进入/conf/example，修改instance.properties

# position info
canal.instance.master.address=127.0.0.1:3306
canal.instance.master.journal.name=
canal.instance.master.position=
canal.instance.master.timestamp=
canal.instance.master.gtid=

# rds oss binlog
canal.instance.rds.accesskey=
canal.instance.rds.secretkey=
canal.instance.rds.instanceId=

# table meta tsdb info
canal.instance.tsdb.enable=true
#canal.instance.tsdb.url=jdbc:mysql://127.0.0.1:3306/canal_tsdb
#canal.instance.tsdb.dbUsername=canal
#canal.instance.tsdb.dbPassword=canal

#canal.instance.standby.address =
#canal.instance.standby.journal.name =
#canal.instance.standby.position =
#canal.instance.standby.timestamp =
#canal.instance.standby.gtid=

# username/password
canal.instance.dbUsername=root
canal.instance.dbPassword=123456
canal.instance.connectionCharset = UTF-8
# enable druid Decrypt database password
canal.instance.enableDruid=false
#canal.instance.pwdPublicKey=MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALK4BUxdDltRRE5/zXpVEVPUgunvscYFtEip3pmLlhrWpacX7y7GCMo2/JM6LeHmiiNdH1FWgGCpUfircSwlWKUCAwEAAQ==

# table regex
canal.instance.filter.regex=.*\\..*
# table black regex
canal.instance.filter.black.regex=mysql\\.slave_.*
# table field filter(format: schema1.tableName1:field1/field2,schema2.tableName2:field1/field2)
#canal.instance.filter.field=test1.t_product:id/subject/keywords,test2.t_company:id/name/contact/ch
# table field black filter(format: schema1.tableName1:field1/field2,schema2.tableName2:field1/field2)
#canal.instance.filter.black.field=test1.t_product:subject/product_image,test2.t_company:id/name/contact/ch

# mq config
canal.mq.topic=example
# dynamic topic route by schema or table regex
#canal.mq.dynamicTopic=mytest1.user,mytest2\\..*,.*\\..*
canal.mq.partition=0
# hash partition config
#canal.mq.partitionsNum=3
#canal.mq.partitionHash=test.table:id^name,.*\\..*
#canal.mq.dynamicTopicPartitionNum=test.*:4,mycanal:6
#################################################

之后进入到bin目录下启动startup就可以了。

3.Mysql准备工作

/*
SQLyog Community v13.2.0 (64 bit)
MySQL - 8.0.33 : Database - shop
*********************************************************************
*/

/*!40101 SET NAMES utf8 */;

/*!40101 SET SQL_MODE=''*/;

/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
CREATE DATABASE /*!32312 IF NOT EXISTS*/`shop` /*!40100 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci */ /*!80016 DEFAULT ENCRYPTION='N' */;

USE `shop`;

/*Table structure for table `brand` */

DROP TABLE IF EXISTS `brand`;

CREATE TABLE `brand` (
  `id` INT NOT NULL AUTO_INCREMENT COMMENT '品牌id',
  `name` VARCHAR(100) NOT NULL COMMENT '品牌名称',
  `image` VARCHAR(1000) DEFAULT '' COMMENT '品牌图片地址',
  `initial` VARCHAR(1) DEFAULT '' COMMENT '品牌的首字母',
  `sort` INT DEFAULT NULL COMMENT '排序',
  PRIMARY KEY (`id`)
) ENGINE=INNODB AUTO_INCREMENT=14 DEFAULT CHARSET=utf8mb3 COMMENT='品牌表';

/*Data for the table `brand` */

INSERT  INTO `brand`(`id`,`name`,`image`,`initial`,`sort`) VALUES 
(11,'华为','https://sklll.oss-cn-beijing.aliyuncs.com/secby/eed72cc4-a9c1-4010-949a-03cef5b933d6.jpg','',NULL),
(12,'中兴','https://sklll.oss-cn-beijing.aliyuncs.com/secby/4fedb361-5ab3-4ad0-a667-580c1f37dff0.jpg','',NULL),
(13,'大疆','https://sklll.oss-cn-beijing.aliyuncs.com/secby/e8382c48-0487-4a9b-8fd0-a3716c3eea19.jpg','',NULL);

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

4. 公共依赖包

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

        <!--MyBatis Plus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.2</version>
        </dependency>

        <!--MySQL-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

        <!--Redis-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

        <!--Nacos-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
    </dependencies>

5. Redis缓存设计

这里基于Springcloud Alibaba进行设计，对应的服务名称为mall-goods

bootstrap.yaml代码如下：

server:
  port: 8081
spring:
  application:
    name: mall-goods
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/shop?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
    username: root
    password: 123456
  cloud:
    nacos:
      config:
        file-extension: yaml
        server-addr: localhost:8848
      discovery:
        #Nacos的注册地址
        server-addr: localhost:8848

  redis:
    host: xx //改为自己redis ip地址
    port: 6379

导入RedisConfig配置

@Configuration
public class RedisConfig {

    @Bean
    public RedisTemplate<String,Object> redisTemplate(RedisConnectionFactory factory){
        RedisTemplate<String,Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(factory);
        GenericJackson2JsonRedisSerializer serializer = new GenericJackson2JsonRedisSerializer();
        // 值采用json序列化
        redisTemplate.setValueSerializer(serializer);
        //使用StringRedisSerializer来序列化和反序列化redis的key值
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        // 设置hash key 和value序列化模式
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(serializer);
        redisTemplate.afterPropertiesSet();
        return redisTemplate;
    }

    @Bean
    public RedisCacheManager redisCacheManager(RedisTemplate redisTemplate) {
        RedisCacheWriter redisCacheWriter = RedisCacheWriter.nonLockingRedisCacheWriter(redisTemplate.getConnectionFactory());
        RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig()
                .entryTtl(Duration.ofHours(12))//设置默认缓存时间
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(redisTemplate.getValueSerializer()));
        return new RedisCacheManager(redisCacheWriter, redisCacheConfiguration);
    }
}

对于Brand进行redis缓存设计

在主启动类上添加@EnableCaching开启缓存。

**

@Cacheable

** 注解可以标记一个方法需要被缓存。在注解中，可以指定缓存的名称和缓存的键。当方法被执行时，Spring Boot 会先查找缓存，如果缓存中存在相应的数据，则直接从缓存中读取，否则执行方法并将结果缓存到缓存中。

**

@CachePut

**注解可以标记一个方法需要更新缓存。在注解中，可以指定缓存的名称和缓存的键。当方法被执行时，Spring Boot 会更新缓存中的数据。

**

@CacheEvict

** 注解可以标记一个方法需要删除缓存。在注解中，可以指定缓存的名称和缓存的键。当方法被执行时，Spring Boot 会删除缓存中对应的数据。

代码如下：

@RestController
@RequestMapping("/brand")
public class BrandController {

    @Autowired
    BrandService brandService;

    @GetMapping("/{id}")
    @Cacheable(value = "brand",key = "#id")
    public Brand search(@PathVariable(value = "id")Integer id){
        return brandService.getById(id);
    }
     /****
     * 添加缓存
     */
    @PostMapping
    @CachePut(value = "brand",key = "#brand.id")
    public Brand add(@RequestBody Brand brand){
        return brand;
    }

    /****
     * 修改缓存
     */
    @PutMapping
    @CachePut(value = "brand",key = "#brand.id")
    public Brand update(@RequestBody Brand brand){
        return brand;
    }

    /****
     * 删除缓存
     */
    @DeleteMapping("/{id}")
    @CacheEvict(value = "brand",key = "#id")
    public void delete(@PathVariable(value = "id")Integer id){
    }
}

6. mall-canal-service

这里微服务名称为mall-canal-service，监控Mysql数据库数据变化进行实时的更新缓存。

除公共依赖外导入依赖

     <dependency>
            <groupId>top.javatool</groupId>
            <artifactId>canal-spring-boot-starter</artifactId>
            <version>1.2.1-RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-loadbalancer</artifactId>
        </dependency>

bootstrap.yaml设计如下：

server:
  port: 8083
spring:
  application:
    name: mall-canal
  cloud:
    nacos:
      config:
        file-extension: yaml
        server-addr: localhost:8848
      discovery:
        #Nacos的注册地址
        server-addr: localhost:8848
#Canal配置
canal:
  server: localhost:11111
  destination: example

设计Feign接口

@FeignClient(value = "mall-goods",contextId = "brand")//服务名字
public interface BrandFeign {

    @GetMapping("/brand/{id}")
    Brand search(@PathVariable(value = "id")Integer id);

    @PostMapping("/brand")
    Brand add(@RequestBody Brand brand);

    /****
     * 修改方法
     */
    @PutMapping("/brand")
     Brand update(@RequestBody Brand brand);

    /****
     * 删除方法
     */
    @DeleteMapping("/brand/{id}")
    void delete(@PathVariable(value = "id")Integer id);

}

Canal实时监控Mysql数据库变化，代码设计如下：

@Component
@CanalTable(value = "brand")
public class BrandHandler implements EntryHandler<Brand> {

    @Autowired
    BrandFeign brandFeign;

    @Override
    public void insert(Brand brand) {
        System.out.println(brand);
        brandFeign.add(brand);
    }

    @Override
    public void update(Brand before, Brand after) {
        System.out.println(after);
        brandFeign.update(after);
    }

    @Override
    public void delete(Brand brand) {
        System.out.println(brand);
        brandFeign.delete(brand.getId());
    }
}

在MallCanalApplication主启动类上添加@EnableFeignClients(basePackages = {"org.example.feign"})，包名为feign接口路径。

注意：本人在使用canal时，数据库有非varchar类型的null值，在运行时会抛异常错误。

    at top.javatool.canal.client.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:52) ~[canal-client-1.2.1-RELEASE.jar:na]
    at top.javatool.canal.client.handler.impl.AsyncMessageHandlerImpl.lambda$handleMessage$0(AsyncMessageHandlerImpl.java:30) ~[canal-client-1.2.1-RELEASE.jar:na]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) ~[na:1.8.0_281]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) ~[na:1.8.0_281]
    at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_281]
Caused by: java.lang.NumberFormatException: For input string: ""
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) ~[na:1.8.0_281]

代码运行后，经过测试成功。