canal结合Redis和MySQL如何实现（JAVA）

canal工作原理

canal是alibaba开发的一个开源的中间件，官网网址为https://github.com/alibaba/canal/wiki
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 (即 canal )
• canal 解析 binary log 对象(原始为 byte 流)

使用步骤

1、配置MySQL

① 在sql中输入查询语句

SHOW VARIABLES LIKE 'log_bin';

该项数据的Value值为OFF，说明binlog的写入功能没有开启，若已经开启，可以直接跳到④。
② 开启binlog的写入功能
找到mysql的安装目录，打开其中的my.ini文件，在 [mysqld] 下加入以下配置：

log-bin=mysql-bin #开启 binlog
binlog-format=ROW #选择 ROW 模式
server_id=1    #配置MySQL replaction需要定义，不要和canal的 slaveId重复

ROW模式：除了记录sql语句之外，还会记录每个字段的变化情况，能够清楚的记录每行数据的变化历史，但会占用较多的空间。
STATEMENT模式：只记录了sql语句，但是没有记录上下文信息，在进行数据恢复的时候可能会导致数据的丢失情况；
MIX模式：比较灵活的记录，理论上说当遇到了表结构变更的时候，就会记录为statement模式。当遇到了数据更新或者删除情况下就会变为row模式；

然后输入以下命令重启mysql

net stop mysql
net start mysql

③ 再次查看mysql， 若value值变为ON，则说明配置成功

SHOW VARIABLES LIKE 'log_bin';

④授权canal连接mysql
查看mysql中自带的用户表（存在名为mysql的数据库中，该数据库是安装后自带的）

SELECT * FROM mysql.`user`

创建canal用户

DROP USER IF EXISTS 'canal'@'%';
CREATE USER 'canal'@'%' IDENTIFIED BY 'canal';  
GRANT ALL PRIVILEGES ON *.* TO 'canal'@'%' IDENTIFIED BY 'canal';  
FLUSH PRIVILEGES;

最后再对该表进行查询，得到以下结果，则操作无误

2、配置canal服务端

• 到canal安装包地址 下载
  canal.deployer-1.1.7.tar.gz 文件，解压至虚拟机自建的mycanal目录下（目录名可以是自己定的）。
• 修改/mycanal/conf/example路径下的instance.properties文件
  将address设为自己主机的地址
  
  将账户换为自己的账户（一般都不用更改）
• 进入/mycanal/bin路径下，执行启动命令

./startup.sh

• 进入/mycanal/logs/canal目录下，查看canal.log日志文件，若最后出现is running now则说明启动成功
  

3、java使用canal

• 在工程的pom文件中，引入以下依赖

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.14</version>
        <relativePath/>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <junit.version>4.12</junit.version>
        <log4j.version>1.2.17</log4j.version>
        <lombok.version>1.16.18</lombok.version>
        <mysql.version>5.1.47</mysql.version>
        <druid.version>1.1.16</druid.version>
        <mapper.version>4.1.5</mapper.version>
        <mybatis.spring.boot.version>1.3.0</mybatis.spring.boot.version>
    </properties>

    <dependencies>
        <!--canal-->
        <dependency>
            <groupId>com.alibaba.otter</groupId>
            <artifactId>canal.client</artifactId>
            <version>1.1.0</version>
        </dependency>
        <!--SpringBoot通用依赖模块-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <!--swagger2-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.9.2</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.9.2</version>
        </dependency>
        <!--SpringBoot与Redis整合依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
        </dependency>
        <!--SpringBoot与AOP-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
        </dependency>
        <!--Mysql数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <!--SpringBoot集成druid连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>${druid.version}</version>
        </dependency>
        <!--mybatis和springboot整合-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>${mybatis.spring.boot.version}</version>
        </dependency>
        <!--通用基础配置junit/devtools/test/log4j/lombok/hutool-->
        <!--hutool-->
        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.2.3</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
            <optional>true</optional>
        </dependency>
        <!--persistence-->
        <dependency>
            <groupId>javax.persistence</groupId>
            <artifactId>persistence-api</artifactId>
            <version>1.0.2</version>
        </dependency>
        <!--通用Mapper-->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper</artifactId>
            <version>${mapper.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
            <version>3.8.0</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

• 更改yml文件（将其中的数据库名，数据库用户名，数据库密码替换成自己的）

server.port=5555

# ========================alibaba.druid=====================
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/bigdata?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.druid.test-while-idle=false

• 在config中添加工具类

package com.atguigu.canal.util;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;


public class RedisUtils
{
    public static final String  REDIS_IP_ADDR = "自己redis所在的ip地址";
    public static final String  REDIS_pwd = "redis密码";
    public static JedisPool jedisPool;

    static {
        JedisPoolConfig jedisPoolConfig=new JedisPoolConfig();
        jedisPoolConfig.setMaxTotal(20);
        jedisPoolConfig.setMaxIdle(10);
        jedisPool=new JedisPool(jedisPoolConfig,REDIS_IP_ADDR,6379,10000,REDIS_pwd);
    }

    public static Jedis getJedis() throws Exception {
        if(null!=jedisPool){
            return jedisPool.getResource();
        }
        throw new Exception("Jedispool is not ok");
    }

}

• 编写调动canal和redis的代码
• 该代码中printEntry方法和main方法是canal官方给出的官方程序，可前往查看
• 连接池采用jedis
• https://github.com/alibaba/canal/wiki/ClientExample

package com.atguigu.canal.biz;

import com.alibaba.fastjson.JSONObject;
import com.alibaba.otter.canal.client.CanalConnector;
import com.alibaba.otter.canal.client.CanalConnectors;
import com.alibaba.otter.canal.protocol.CanalEntry.*;
import com.alibaba.otter.canal.protocol.Message;
import com.atguigu.canal.util.RedisUtils;
import redis.clients.jedis.Jedis;
import java.net.InetSocketAddress;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.TimeUnit;


public class RedisCanalClientExample
{
    public static final Integer _60SECONDS = 60;
    public static final String  REDIS_IP_ADDR = "自己redis所在地址";

    private static void redisInsert(List<Column> columns)
    {
        JSONObject jsonObject = new JSONObject();
        for (Column column : columns)
        {
            System.out.println(column.getName() + " : " + column.getValue() + "    update=" + column.getUpdated());
            jsonObject.put(column.getName(),column.getValue());
        }
        if(columns.size() > 0)
        {
            try(Jedis jedis = RedisUtils.getJedis())
            {
                jedis.set(columns.get(0).getValue(),jsonObject.toJSONString());
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }


    private static void redisDelete(List<Column> columns)
    {
        JSONObject jsonObject = new JSONObject();
        for (Column column : columns)
        {
            jsonObject.put(column.getName(),column.getValue());
        }
        if(columns.size() > 0)
        {
            try(Jedis jedis = RedisUtils.getJedis())
            {
                jedis.del(columns.get(0).getValue());
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }

    private static void redisUpdate(List<Column> columns)
    {
        JSONObject jsonObject = new JSONObject();
        for (Column column : columns)
        {
            System.out.println(column.getName() + " : " + column.getValue() + "    update=" + column.getUpdated());
            jsonObject.put(column.getName(),column.getValue());
        }
        if(columns.size() > 0)
        {
            try(Jedis jedis = RedisUtils.getJedis())
            {
                jedis.set(columns.get(0).getValue(),jsonObject.toJSONString());
                System.out.println("---------update after: "+jedis.get(columns.get(0).getValue()));
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }

    public static void printEntry(List<Entry> entrys) {
        for (Entry entry : entrys) {
            if (entry.getEntryType() == EntryType.TRANSACTIONBEGIN || entry.getEntryType() == EntryType.TRANSACTIONEND) {
                continue;
            }

            RowChange rowChage = null;
            try {
                //获取变更的row数据
                rowChage = RowChange.parseFrom(entry.getStoreValue());
            } catch (Exception e) {
                throw new RuntimeException("ERROR ## parser of eromanga-event has an error,data:" + entry.toString(),e);
            }
            //获取变动类型
            EventType eventType = rowChage.getEventType();
            System.out.println(String.format("================&gt; binlog[%s:%s] , name[%s,%s] , eventType : %s",
                    entry.getHeader().getLogfileName(), entry.getHeader().getLogfileOffset(),
                    entry.getHeader().getSchemaName(), entry.getHeader().getTableName(), eventType));

            for (RowData rowData : rowChage.getRowDatasList()) {
                if (eventType == EventType.INSERT) {
                    redisInsert(rowData.getAfterColumnsList());
                } else if (eventType == EventType.DELETE) {
                    redisDelete(rowData.getBeforeColumnsList());
                } else {//EventType.UPDATE
                    redisUpdate(rowData.getAfterColumnsList());
                }
            }
        }
    }


    public static void main(String[] args)
    {
        System.out.println("---------O(∩_∩)O哈哈~ initCanal() main方法-----------");

        //=================================
        // 创建链接canal服务端
        CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress(REDIS_IP_ADDR,
                11111), "example", "", "");
        int batchSize = 1000;
        //空闲空转计数器
        int emptyCount = 0;
        System.out.println("---------------------canal init OK，开始监听mysql变化------");
        try {
            connector.connect();
            //connector.subscribe(".*\\..*");
            connector.subscribe("bigdata.t_user");  //只监控bigdata数据库中的t_user表
            connector.rollback();
            int totalEmptyCount = 10 * _60SECONDS;
            while (emptyCount < totalEmptyCount) {
                System.out.println("我是canal，每秒一次正在监听:"+ UUID.randomUUID().toString());
                Message message = connector.getWithoutAck(batchSize); // 获取指定数量的数据
                long batchId = message.getId();
                int size = message.getEntries().size();
                if (batchId == -1 || size == 0) {
                    emptyCount++;
                    try { TimeUnit.SECONDS.sleep(1); } catch (InterruptedException e) { e.printStackTrace(); }
                } else {
                    //计数器重新置零
                    emptyCount = 0;
                    printEntry(message.getEntries());
                }
                connector.ack(batchId); // 提交确认
                // connector.rollback(batchId); // 处理失败, 回滚数据
            }
            System.out.println("已经监听了"+totalEmptyCount+"秒，无任何消息，请重启重试......");
        } finally {
            connector.disconnect();
        }
    }
}

最后运行程序，启动成功

若报错，可参考
https://blog.youkuaiyun.com/Taurus22/article/details/136888302