一、Canal的搭建使用

Canal简介

我们项目中用的Canal的目的是，当数据库中数据有增删改查了，然后将这些数据做自动的处理。

Canal搭建

Canal分为Server和Client端。
它的原理和Mysql的主从是很相似的，都是读取的bin log日志。

（1）Mysql服务器的设置

https://blog.csdn.net/yehongzhi1994/article/details/107880162

（2）安装Cannal

我下载的是1.1.5版本的canal.deployer

打开conf下面的properties文件

修改配置文件

#################################################
## mysql serverId , v1.0.26+ will autoGen
# canal.instance.mysql.slaveId=0

# enable gtid use true/false
canal.instance.gtidon=false

# position info
#canal.instance.master.address=127.0.0.1:3306
#数据库地址
canal.instance.master.address=192.168.241.6:3306
#binlog日志名称
canal.instance.master.journal.name=mysql-bin.000332
# mysql 主库连接时起始的binlog偏移量
canal.instance.master.position=49565061
#mysql主库连接时起始的binlog的时间戳
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 在MySQL服务器授权的账号密码
canal.instance.dbUsername=crm2021_dev
canal.instance.dbPassword=bfdds06fd
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
#################################################

然后启动bin中的startup.bat

(3) 客户端

引POM文件

   <dependency>
            <groupId>com.alibaba.otter</groupId>
            <artifactId>canal.client</artifactId>
            <version>1.1.5</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.otter</groupId>
            <artifactId>canal.protocol</artifactId>
            <version>1.1.5</version>
            <exclusions>
                <exclusion>
                    <groupId>org.apache.zookeeper</groupId>
                    <artifactId>zookeeper</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>com.alibaba</groupId>
                    <artifactId>fastjson</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

Client代码

package com.hc.zxd.cannal.deploy;

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 lombok.Data;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.stereotype.Component;


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

/**
 * @Classname CannalClient
 * @Description TODO
 * @Date 2021/10/27 11:21
 * @Author zhaoxiaodong
 */

@Component
public class CannalClient implements InitializingBean {

    private final static int BATCH_SIZE = 1000;


    @Override
    public void afterPropertiesSet() throws Exception {
        // 创建链接
        CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress("127.0.0.1", 11111), "example", "", "");
        try {
            //打开连接
            connector.connect();
            //订阅数据库表,全部表
            connector.subscribe(".*\\..*");
            //回滚到未进行ack的地方，下次fetch的时候，可以从最后一个没有ack的地方开始拿
            connector.rollback();
            while (true) {
                //获取指定数量的数据
                Message message = connector.getWithoutAck(BATCH_SIZE);
                //获取批量ID
                long batchId = message.getId();
                //获取批量的数量
                int size = message.getEntries().size();
                //如果没有数据
                if (batchId == -1 || size == 0) {
                    try {
                        //线程休眠2秒
                        Thread.sleep(2000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                } else {
                    //如果有数据，处理数据
                    printEntry(message.getEntries());
                }
                //进行 batch id 的确认。确认之后，小于等于此 batchId 的 Message 都会被确认。
                connector.ack(batchId);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            connector.disconnect();
        }
    }

    /**
     * @param entries
     * @return void
     * @Author zhaoxiaodong
     * @Description 打印
     * @Date 11:46 2021/10/27
     */
    private static void printEntry(List<CanalEntry.Entry> entries) {
        for (CanalEntry.Entry entry : entries) {
            if (entry.getEntryType() == CanalEntry.EntryType.TRANSACTIONBEGIN || entry.getEntryType() == CanalEntry.EntryType.TRANSACTIONEND) {
                //开启/关闭事务的实体类型，跳过
                continue;
            }
            // RowChange对象，包含了一行数据变化的所有特征
            // 比如isDdl 是否是ddl变更操作 sql 具体的ddl sql beforeColumns afterColumns 变更前后的数据字段等等
            CanalEntry.RowChange rowChange;
            try {
                rowChange=CanalEntry.RowChange.parseFrom(entry.getStoreValue());
            } catch (Exception e) {
                throw new RuntimeException("ERROR ## parser of eromanga-event has an error , data:" + entry.toString(), e);
            }
            //获取操作类型: insert /update /delete类型
            CanalEntry.EventType eventType = rowChange.getEventType();
            //打印Header信息
            System.out.println(String.format("================》; binlog[%s:%s] , name[%s,%s] , eventType : %s",
                    entry.getHeader().getLogfileName(), entry.getHeader().getLogfileOffset(),
                    entry.getHeader().getSchemaName(), entry.getHeader().getTableName(),
                    eventType));
            //判断是否是DDL语句
            if (rowChange.getIsDdl()) {
                System.out.println("================》;isDdl: true,sql:" + rowChange.getSql());
            }
            //获取RowChange对象里的每一行数据，打印出来
            for (CanalEntry.RowData rowData : rowChange.getRowDatasList()) {
                //如果是删除语句
                if (eventType == CanalEntry.EventType.DELETE){
                    printColumn(rowData.getBeforeColumnsList());
                    //如果是新增语句
                }else if (eventType == CanalEntry.EventType.INSERT){
                    printColumn(rowData.getBeforeColumnsList());
                    //如果是更新的语句
                }else {
                    //变更前的数据
                    System.out.println("---->;before");
                    printColumn(rowData.getBeforeColumnsList());
                    //变更后的数据
                    System.out.println("---->;after");
                    printColumn(rowData.getAfterColumnsList());
                }
            }
        }
    }

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

测试
当我们修改数据库值的时候就可以看到变化了在控制台