canal 数据同步组件

q琦一2023-12-29 14:31

canal 数据异构组件

为啥要使用这个组件？

在更新DB的时候不同步更新到redis，es等数据库中，时间太久，而且可能会存在同步失败的问题，因此引入canal去拉取DB的数据，再去更新到redis，es等数据库中，有失败重试和回滚等功能。
canal原理？

canal 伪装成salve向mysql发送dump协议，拿到备份数据binlog,去更新数据到redis，es等数据库中或者通过组装数据之后更新。canal可以拿到更新前的所有数据，更新后的所有数据，更新了哪些数据

canal 组件的使用

1.下载canal组件

下载地址canal组件下载地址

在我的资源中也有canal组件包

解压启动（我是windows版，双击startup.bat）

2.数据库配置

1.开启MySQL , 需要先开启 Binlog 写入功能

sql 复制代码 
[mysqld]
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

2.授权 canal 作为mysql 的slave 的权限

sql 复制代码 
CREATE USER canal IDENTIFIED BY 'canal';  
GRANT SELECT, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'canal'@'%';
-- GRANT ALL PRIVILEGES ON *.* TO 'canal'@'%' ;
FLUSH PRIVILEGES;
3.项目引入jar包
xml 复制代码 
<dependency>
    <groupId>com.alibaba.otter</groupId>
    <artifactId>canal.client</artifactId>
    <version>1.1.4</version>
</dependency>
4.写canal监听数据工具类
java 复制代码 
package com.next.canal;

import com.alibaba.otter.canal.client.CanalConnector;
import com.alibaba.otter.canal.client.CanalConnectors;
import com.alibaba.otter.canal.common.utils.AddressUtils;
import com.alibaba.otter.canal.protocol.CanalEntry;
import com.alibaba.otter.canal.protocol.Message;

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

public class SimpleCanalClientExample {
    public static void main(String args[]) {
        // 创建链接
        CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress(AddressUtils.getHostIp(),
                11111), "example", "", "");
        int batchSize = 1000;
        int emptyCount = 0;
        try {
            connector.connect();
            connector.subscribe(".*\\..*");
            connector.rollback();
            int totalEmptyCount = 120;
            while (emptyCount < totalEmptyCount) {
                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++;
                    System.out.println("empty count : " + emptyCount);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                    }
                } else {
                    emptyCount = 0;
                    // System.out.printf("message[batchId=%s,size=%s] \n", batchId, size);
                    printEntry(message.getEntries());
                }

                connector.ack(batchId); // 提交确认
                // connector.rollback(batchId); // 处理失败, 回滚数据
            }

            System.out.println("empty too many times, exit");
        } 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());
        }
    }
}
5.简单例子使用测试

1.数据库更改user_id从0改为1，再从1改为0

2.查看canal监测的数据（canal可以拿到更新前的所有数据，更新后的所有数据，更新了哪些数据）



6.进一步完善canal监听数据工具类，用于应用例子

1.加入监听器，项目启动时启动

2.使用线程去监听数据

3.替换掉system.out.print()，里面有锁，会阻塞，使用日志打印

4.处理canal监测到的数据

java 复制代码 
package com.next.canal;

import com.alibaba.otter.canal.client.CanalConnector;
import com.alibaba.otter.canal.client.CanalConnectors;
import com.alibaba.otter.canal.common.utils.AddressUtils;
import com.alibaba.otter.canal.protocol.CanalEntry;
import com.alibaba.otter.canal.protocol.Message;
import com.next.dao.TrainNumberDetailMapper;
import com.next.service.TrainNumberService;
import com.next.service.TrainSeatService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.net.InetSocketAddress;
import java.util.List;

/**
 * @desc 不要用system.out.print()里面有锁，会阻塞，用日志打印
 */
@Service
@Slf4j
public class CanalSubscribe implements ApplicationListener<ContextRefreshedEvent> {

    @Resource
    private TrainSeatService trainSeatService;

    @Resource
    private TrainNumberService trainNumberService;

    //监听，启动的时候就开始调用此监听方法
    @Override
    public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
        canalSubscribe();
    }

    private void canalSubscribe() {
        // 创建链接
        CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress(AddressUtils.getHostIp(),
                11111), "example", "", "");
        int batchSize = 1000;
        //使用线程
        new Thread(() -> {
            try {
                log.info("canal subscribe");
                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) {
                        //没有取到数据继续
                        safeSleep(100);
                        continue;
                    }
                    try {
                        log.info("new message,batchIds:{},size:{}", batchId, batchSize);
                        //打印日志
                        printEntry(message.getEntries());
                        // 提交确认
                        connector.ack(batchId);
                    } catch (Exception e2) {
                        log.error("canal data exception,batchIds:{}", batchId, e2);
                        // 处理失败, 回滚数据
                        connector.rollback(batchId);
                    }
                }
            } catch (Exception e3) {
                log.error("canal subscribe exception", e3);
                safeSleep(1000);
                canalSubscribe();
            }
        }).start();
    }

    private void printEntry(List<CanalEntry.Entry> entrys) throws Exception{
        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("RowChange.parse Exception , data:" + entry, e);
            }

            //更新类型-更新，删除，新增
            CanalEntry.EventType eventType = rowChage.getEventType();
            //数据库名
            String schemaName = entry.getHeader().getSchemaName();
            //表名
            String tableName = entry.getHeader().getTableName();
            log.info("name:[{},{}],eventType:{}",schemaName,tableName,eventType);
            for (CanalEntry.RowData rowData : rowChage.getRowDatasList()) {
                if (eventType == CanalEntry.EventType.DELETE) {
                    handleColumn(rowData.getBeforeColumnsList(), eventType, schemaName, tableName);
                } else {
                    handleColumn(rowData.getAfterColumnsList(), eventType, schemaName, tableName);
                }
            }
        }
    }

    //处理canal监测到的数据
    private void handleColumn(List<CanalEntry.Column> columnsList, CanalEntry.EventType eventType, String schemaName, String tableName) throws Exception{
        if(schemaName.contains("12306_seat_")){
            //处理座位变更
            trainSeatService.handle(columnsList,eventType);
        }else if(tableName.equals("train_number")){
            //车次详情处理(实际上是车次信息变更之后才批量处理车次详情)
            trainNumberService.handle(columnsList,eventType);
        }else{
            log.info("drop data,no need care");
        }


    }



    private void safeSleep(int millis) {
        try {
            Thread.sleep(100);
        } catch (Exception e1) {

        }
    }

}

处理canal监测到的数据（拿到改变的数据，放到实体类中，存到redis中）

java 复制代码 
package com.next.service;


import com.alibaba.otter.canal.protocol.CanalEntry;
import com.next.dao.TrainNumberMapper;
import com.next.model.TrainNumber;
import com.next.model.TrainSeat;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;

@Service
@Slf4j
public class TrainSeatService {

    @Resource
    private TrainNumberMapper trainNumberMapper;

    @Resource
    private TrainCacheService trainCacheService;

    //处理座位，canal通过监听座位库，拿到改变的数据，放到实体类中
    public void handle(List<CanalEntry.Column> columns, CanalEntry.EventType eventType) {
        if (eventType != CanalEntry.EventType.UPDATE) {
            log.info("not update,no need care");
            return;
        }
        TrainSeat trainSeat = new TrainSeat();
        boolean isStatusUpdated = false;
        for (CanalEntry.Column column : columns) {
            //票的状态改变了才做下面的操作
            if (column.getName().equals("status")) {
                trainSeat.setStatus(Integer.parseInt(column.getValue()));
                if (column.getUpdated()) {
                    isStatusUpdated = true;
                } else {
                    break;
                }
            } else if (column.getName().equals("id")) {
                trainSeat.setId(Long.parseLong(column.getValue()));
            } else if (column.getName().equals("carriage_number")) {
                trainSeat.setCarriageNumber(Integer.parseInt(column.getValue()));
            } else if (column.getName().equals("row_number")) {
                trainSeat.setRowNumber(Integer.parseInt(column.getValue()));
            } else if (column.getName().equals("seat_number")) {
                trainSeat.setSeatNumber(Integer.parseInt(column.getValue()));
            } else if (column.getName().equals("train_number_id")) {
                trainSeat.setTrainNumberId(Integer.parseInt(column.getValue()));
            } else if (column.getName().equals("ticket")) {
                trainSeat.setTicket(column.getValue());
            } else if (column.getName().equals("from_station_id")) {
                trainSeat.setFromStationId(Integer.parseInt(column.getValue()));
            } else if (column.getName().equals("to_station_id")) {
                trainSeat.setToStationId(Integer.parseInt(column.getValue()));
            }
        }
        if (!isStatusUpdated) {
            log.info("status not update,no need care");
        }
        log.info("train seat update,trainSeat:{}", trainSeat);

        /**
         * 数据存到redis
         * 1.指定座位被占：hash
         * cacheKey:车次_日期  D386_20231001
         * field: carriage_row_seat_fromStationId_toStationId
         * value: 0-空闲 1-占座
         *
         * 2.每个座位详情剩余的座位数
         * cacheKey: 车次_日期_count D386_20231001_count
         * field: fromStationId_toStationId
         * value: 实际座位数
         *
         */

        TrainNumber trainNumber = trainNumberMapper.selectByPrimaryKey(trainSeat.getTrainNumberId());
        //放票
        if (trainSeat.getStatus() == 1) {
            trainCacheService.hset(trainNumber.getName() + "_" + trainSeat.getTicket(),
                    trainSeat.getCarriageNumber() + "_" + trainSeat.getRowNumber() + "_" + trainSeat.getSeatNumber()
                            + "_" + trainSeat.getFromStationId() + "_" + trainSeat.getToStationId(),
                    "0");

            trainCacheService.hincr(trainNumber.getName() + "_" + trainSeat.getTicket() + "_count",
                    trainSeat.getFromStationId() + "_" + trainSeat.getToStationId(),
                    1l);
            log.info("seat+1,trainNumber:{},trainSeat:{}", trainNumber, trainSeat);

            //占票
        } else if (trainSeat.getStatus() == 2) {
            trainCacheService.hset(trainNumber.getName() + "_" + trainSeat.getTicket(),
                    trainSeat.getCarriageNumber() + "_" + trainSeat.getRowNumber() + "_" + trainSeat.getSeatNumber()
                            + "_" + trainSeat.getFromStationId() + "_" + trainSeat.getToStationId(),
                    "1");
            trainCacheService.hincr(trainNumber.getName() + "_" + trainSeat.getTicket() + "_count",
                    trainSeat.getFromStationId() + "_" + trainSeat.getToStationId(),
                    -1l);
            log.info("seat-1,trainNumber:{},trainSeat:{}", trainNumber, trainSeat);
        } else {
            log.info("status update not 1 or 2,no need care");
        }
    }


}

参考文档：canal使用说明文档

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