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目录

1. 背景

2. Windows系统安装canal

3.Mysql准备工作

4. 公共依赖包

5. Redis缓存设计

6. mall-canal-service

---

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-goodsdatasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/shop?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTCusername: rootpassword: 123456cloud:nacos:config:file-extension: yamlserver-addr: localhost:8848discovery:#Nacos的注册地址server-addr: localhost:8848redis:host: xx //改为自己redis ip地址port: 6379

导入RedisConfig配置

@Configuration
public class RedisConfig {@Beanpublic 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;}@Beanpublic 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 {@AutowiredBrandService 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-canalcloud:nacos:config:file-extension: yamlserver-addr: localhost:8848discovery:#Nacos的注册地址server-addr: localhost:8848
#Canal配置
canal:server: localhost:11111destination: 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> {@AutowiredBrandFeign brandFeign;@Overridepublic void insert(Brand brand) {System.out.println(brand);brandFeign.add(brand);}@Overridepublic void update(Brand before, Brand after) {System.out.println(after);brandFeign.update(after);}@Overridepublic 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。