一、简介
Canal是Java开发的基于数据库增量日志解析工具,提供增量数据订阅和消费,目前主要支持MySQL。它的工作原理比较简单,就是将自己伪装成一个MySQL Slave,从Master同步数据。
- 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)
- 解析后的数据再做后续处理
先了解一下MySQL主备复制原理:
- MySQL master 将数据变更写入二进制日志( binary log, 其中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)
- MySQL slave 将 master 的 binary log events 拷贝到它的中继日志(relay log)
- MySQL slave 重放 relay log 中事件,将数据变更反映它自己的数据
二、准备工作
- 对于自建的MySQL,需要开启binlog写入功能,并配置biglog-format为ROW模式,这样才能一行行的检测到数据的变动
[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
- 创建canal用户并授权其作为MySQL Slave的权限
CREATE USER canal IDENTIFIED BY 'canal';
GRANT SELECT, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'canal'@'%';
FLUSH PRIVILEGES;
三、启动Canal服务
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下载canal
我们这里使用的是canal.deployer-1.1.4.tar.gz
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解压
tar zxvf canal.deployer-1.1.4.tar.gz cd canal.deployer-1.1.4
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修改配置文件,主要是MySQL Master的连接信息
打开文件
conf/example/instance.properties
################################################# ## mysql serverId , v1.0.26+ will autoGen canal.instance.mysql.slaveId=1 # enable gtid use true/false canal.instance.gtidon=false # 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=canal canal.instance.dbPassword=canal canal.instance.defaultDatabaseName=test_canal 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= # 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.instance.connectionCharset 代表数据库的编码方式对应到 java 中的编码类型,比如 UTF-8,GBK , ISO-8859-1
- 如果系统是1个 cpu,需要将 canal.instance.parser.parallel 设置为 false
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启动canal
sh bin/startup.sh
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查看server和instance日志
2020-04-23 23:48:59.048 [main] INFO com.alibaba.otter.canal.deployer.CanalLauncher - ## set default uncaught exception handler 2020-04-23 23:48:59.097 [main] INFO com.alibaba.otter.canal.deployer.CanalLauncher - ## load canal configurations 2020-04-23 23:48:59.110 [main] INFO com.alibaba.otter.canal.deployer.CanalStarter - ## start the canal server. 2020-04-23 23:48:59.178 [main] INFO com.alibaba.otter.canal.deployer.CanalController - ## start the canal server[192.168.0.106(192.168.0.106):11111] 2020-04-23 23:49:00.243 [main] INFO com.alibaba.otter.canal.deployer.CanalStarter - ## the canal server is running now ......
er.setConnectionCharset(java.lang.String)] 2020-04-23 23:48:59.793 [main] INFO c.a.o.c.i.spring.support.PropertyPlaceholderConfigurer - Loading properties file from class path resource [canal.properties] 2020-04-23 23:48:59.794 [main] INFO c.a.o.c.i.spring.support.PropertyPlaceholderConfigurer - Loading properties file from class path resource [example/instance.properties] 2020-04-23 23:49:00.192 [main] INFO c.a.otter.canal.instance.spring.CanalInstanceWithSpring - start CannalInstance for 1-example 2020-04-23 23:49:00.199 [main] WARN c.a.o.canal.parse.inbound.mysql.dbsync.LogEventConvert - --> init table filter : ^.*\..*$ 2020-04-23 23:49:00.199 [main] WARN c.a.o.canal.parse.inbound.mysql.dbsync.LogEventConvert - --> init table black filter : 2020-04-23 23:49:00.206 [main] INFO c.a.otter.canal.instance.core.AbstractCanalInstance - start successful....
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关闭
sh bin/stop.sh
四、创建Java工程
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引入canal和redis包
<dependency> <groupId>com.alibaba.otter</groupId> <artifactId>canal.client</artifactId> <version>1.1.4</version> </dependency> <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.4.2</version> </dependency>
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创建RedisUtils工具类
import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisPool; import redis.clients.jedis.JedisPoolConfig; public class RedisUtils { // Redis服务器IP private static String ADDR = "127.0.0.1"; // Redis的端口号 private static int PORT = 6379; // 访问密码 private static String AUTH = ""; // 可用连接实例的最大数目,默认值为8; // 如果赋值为-1,则表示不限制;如果pool已经分配了maxActive个jedis实例,则此时pool的状态为exhausted(耗尽)。 private static int MAX_ACTIVE = 1024; // 控制一个pool最多有多少个状态为idle(空闲的)的jedis实例,默认值也是8。 private static int MAX_IDLE = 200; // 等待可用连接的最大时间,单位毫秒,默认值为-1,表示永不超时。如果超过等待时间,则直接抛出JedisConnectionException; private static int MAX_WAIT = 10000; // 过期时间 protected static int expireTime = 60 * 60 * 24; // 连接池 protected static JedisPool pool; /** * 静态代码,只在初次调用一次 */ static { JedisPoolConfig config = new JedisPoolConfig(); //最大连接数 config.setMaxTotal(MAX_ACTIVE); //最多空闲实例 config.setMaxIdle(MAX_IDLE); //超时时间 config.setMaxWaitMillis(MAX_WAIT); // config.setTestOnBorrow(false); pool = new JedisPool(config, ADDR, PORT, 1000); } /** * 获取jedis实例 */ protected static synchronized Jedis getJedis() { Jedis jedis = null; try { jedis = pool.getResource(); } catch (Exception e) { e.printStackTrace(); if (jedis != null) { pool.returnBrokenResource(jedis); } } return jedis; } /** * 释放jedis资源 * * @param jedis * @param isBroken */ protected static void closeResource(Jedis jedis, boolean isBroken) { try { if (isBroken) { pool.returnBrokenResource(jedis); } else { pool.returnResource(jedis); } } catch (Exception e) { } } /** * 是否存在key * * @param key */ public static boolean existKey(String key) { Jedis jedis = null; boolean isBroken = false; try { jedis = getJedis(); jedis.select(0); return jedis.exists(key); } catch (Exception e) { isBroken = true; } finally { closeResource(jedis, isBroken); } return false; } /** * 删除key * * @param key */ public static void delKey(String key) { Jedis jedis = null; boolean isBroken = false; try { jedis = getJedis(); jedis.select(0); jedis.del(key); } catch (Exception e) { isBroken = true; } finally { closeResource(jedis, isBroken); } } /** * 取得key的值 * * @param key */ public static String stringGet(String key) { Jedis jedis = null; boolean isBroken = false; String lastVal = null; try { jedis = getJedis(); jedis.select(0); lastVal = jedis.get(key); jedis.expire(key, expireTime); } catch (Exception e) { isBroken = true; } finally { closeResource(jedis, isBroken); } return lastVal; } /** * 添加string数据 * * @param key * @param value */ public static String stringSet(String key, String value) { Jedis jedis = null; boolean isBroken = false; String lastVal = null; try { jedis = getJedis(); jedis.select(0); lastVal = jedis.set(key, value); jedis.expire(key, expireTime); } catch (Exception e) { e.printStackTrace(); isBroken = true; } finally { closeResource(jedis, isBroken); } return lastVal; } /** * 添加hash数据 * * @param key * @param field * @param value */ public static void hashSet(String key, String field, String value) { boolean isBroken = false; Jedis jedis = null; try { jedis = getJedis(); if (jedis != null) { jedis.select(0); jedis.hset(key, field, value); jedis.expire(key, expireTime); } } catch (Exception e) { isBroken = true; } finally { closeResource(jedis, isBroken); } } }
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创建CanalClient
import java.net.InetSocketAddress; import java.util.List; import com.alibaba.fastjson.JSONObject; 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.Message; import com.alibaba.otter.canal.protocol.CanalEntry.*; public class CanalClient { public static void main(String args[]) { // 创建链接 CanalConnector connector = CanalConnectors .newSingleConnector(new InetSocketAddress(AddressUtils.getHostIp(), 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) { try { Thread.sleep(500); } catch (InterruptedException e) { } } else { printEntry(message.getEntries()); } connector.ack(batchId); // 提交确认 } } finally { connector.disconnect(); } } private static void printEntry(List<Entry> entrys) { for (Entry entry : entrys) { if (entry.getEntryType() == EntryType.TRANSACTIONBEGIN || entry.getEntryType() == EntryType.TRANSACTIONEND) { continue; } RowChange rowChage = null; try { rowChage = RowChange.parseFrom(entry.getStoreValue()); } catch (Exception e) { throw new RuntimeException("ERROR ## parser of eromanga-event has an error , data:" + entry.toString(), e); } EventType eventType = rowChage.getEventType(); for (RowData rowData : rowChage.getRowDatasList()) { if (eventType == EventType.DELETE) { // 删除,获取删除前的数据 redisDelete(rowData.getBeforeColumnsList()); } else if (eventType == EventType.INSERT) { // 新增,获取新增后的数据 redisSet(rowData.getAfterColumnsList()); } else { // 修改,获取修改后的数据 // printColumn(rowData.getBeforeColumnsList()); redisSet(rowData.getAfterColumnsList()); } } } } private static void redisSet(List<Column> columns) { JSONObject json = new JSONObject(); // 字段和值的列表,放入json,后续作为redis的值 for (Column column : columns) { json.put(column.getName(), column.getValue()); } if (columns.size() > 0) { System.out.println("set key: " + columns.get(0).getValue() + ", value: " + json.toJSONString()); // 获取第一列主键的数据 RedisUtils.stringSet("demo:" + columns.get(0).getValue(), json.toJSONString()); } } private static void redisDelete(List<Column> columns) { JSONObject json = new JSONObject(); for (Column column : columns) { json.put(column.getName(), column.getValue()); } if (columns.size() > 0) { System.out.println("delete key: " + columns.get(0).getValue()); RedisUtils.delKey("demo:" + columns.get(0).getValue()); } } }
五、验证
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启动CanalClient.java
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创建数据表test_canal
CREATE TABLE `test_canal` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(11) DEFAULT NULL, `age` int(11) DEFAULT 0, `sex` varchar(11) DEFAULT '男', PRIMARY KEY (`id`), KEY `idx_name` (`name`) USING BTREE ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8mb4
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校验一下Redis中目前是否为空
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插入数据
- 插入三条数据
INSERT INTO test_canal(name, age, sex) VALUES('cc0', 3, '男'); INSERT INTO test_canal(name, age, sex) VALUES('cc1', 6, '女'); INSERT INTO test_canal(name, age, sex) VALUES('cc2', 9, '男');
- 查看控制台
- 查询Redis中的数据
验证成功,数据同步达到了毫秒级。
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修改数据
- 修改id=5的数据
UPDATE test_canal SET sex='11' WHERE id=5;
- 查看控制台
- 查询Redis中的数据
验证成功,Redis中的sex列已经修改为何MySQL表中一致了
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删除数据
- 删除id=5的数据
DELETE FROM test_canal WHERE id=5;
- 查看控制台
- 查询Redis中的数据
验证成功,Redis中的"demo:5"已经被删除了
总结
关于更多的Canal介绍可以查看官方文档:Canal官方介绍,源端目前只支持MySQL,目标端可以是任意组件