目录
canal [k?'n?l] ,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:
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:
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。
/*
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 */;
<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>
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){
}
}
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。