canal介绍

canal是阿里开源的数据库同步框架,采用非侵入式方式,解析mysql的binary log,再发送到目的地,目的地可是mq,hbase,mysql,es等.

本章流程

1. 开启mysql的bin-log日志
2. 创建mysql用户获取bin-log日志
3. canal采集bin-log日志
4. canal-client获取mysql变化信息

开启bin-log日志

只需要在mysqld.cnf新增配置

server-id=1
log-bin=mysql-bin

创建mysql用户

create user canal@‘%‘ IDENTIFIED by ‘canal‘;
GRANT SELECT, REPLICATION SLAVE, REPLICATION CLIENT,SUPER ON *.* TO ‘canal‘@‘%‘;
FLUSH PRIVILEGES;

配置canal

# 配置文件1：canal-server/conf/canal.properties
# 端口
canal.port = 11111

# 配置文件2：canal-server/conf/example/instance.properties
# 数据库连接信息
canal.instance.master.address=192.168.41.128:3307
canal.instance.dbUsername=canal
canal.instance.dbPassword=canal
# 监听的表(正则表达式)
canal.instance.filter.regex=.*\\..*
# 主题
canal.mq.topic=example

启动mysql/canal

# 本地测试采用docker方式启动
docker run -d --name mysql -p 3307:3306 -e MYSQL_ROOT_PASSWORD=123456 -v $PWD/mysqld.cnf:/etc/mysql/mysql.conf.d/mysqld.cnf  hub.c.163.com/library/mysql:5.7

docker run -p 11111:11111 --name canal -d docker.io/canal/canal-server

编写canal-client

package com.deri.stream.canal;

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 java.net.InetSocketAddress;
import java.util.List;

/**
 * @ClassName: Main
 * @Description: TODO
 * @Author: wuzhiyong
 * @Time: 2021/6/11 9:41
 * @Version: v1.0
 **/
public class Main {
    public static void main(String[] args) throws InterruptedException {
        CanalConnector connector = CanalConnectors.newSingleConnector(
                new InetSocketAddress("192.168.41.128",11111), "example", "", "");
        int batchSize = 1000;
        try {
            connector.connect();
            connector.subscribe(".*\\..*");
            connector.rollback();
            while (true) {
                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) {
                    // 没有变化,等一秒钟再去拉取数据
                   Thread.sleep(1000);
                } else {
                    printEntry(message.getEntries());
                }
                connector.ack(batchId); // 提交确认
                // connector.rollback(batchId); // 处理失败, 回滚数据
            }
        } finally {
            connector.disconnect();
        }
    }

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

            CanalEntry.RowChange rowChage = null;
            try {
                rowChage = CanalEntry.RowChange.parseFrom(entry.getStoreValue());
            } catch (Exception e) {
                throw new RuntimeException("ERROR ## parser of eromanga-event has an error , data:" + entry.toString(),
                        e);
            }

            CanalEntry.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 (CanalEntry.RowData rowData : rowChage.getRowDatasList()) {
                if (eventType == CanalEntry.EventType.DELETE) {
                    printColumn(rowData.getBeforeColumnsList());
                } else if (eventType == CanalEntry.EventType.INSERT) {
                    printColumn(rowData.getAfterColumnsList());
                } else {
                    System.out.println("-------&gt; before");
                    printColumn(rowData.getBeforeColumnsList());
                    System.out.println("-------&gt; after");
                    printColumn(rowData.getAfterColumnsList());
                }
            }
        }
    }

    private static void printColumn(List<CanalEntry.Column> columns) {
        for (CanalEntry.Column column : columns) {
            System.out.println(column.getName() + " : " + column.getValue() + "    update=" + column.getUpdated());
        }
    }
}

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