一 canal的扫盲
1.1 canal的介绍
canal是阿里巴巴旗下的一款开源项目，使用java语言进行开发，基于数据库增量日志解析，提供增量数据订阅与消费的功能。是一款很好用的数据库同步工具。目前只支持mysql。
二 canal的搭建
2.1 架构流程
2.2 配置服务器mysql
canal的原理是基于mysql binlog技术，所以，这里一定要开启mysql的binlog写入的功能。
1.开启mysql服务：service mysqld start 或 service mysql start
2.检测binlog功能是否开启，如果是off，则没有开启，如果是on表示开启
show variables like ‘log_bin’;
3.如果binlog的显示为off，则修改配置文件 my.cnf 进行配置开启
vi /etc/my.cnf
# set zhucongfuzhiserver_id = 86 # 设置服务器编号log_bin = master-bin # 启用二进制日志，并设置二进制日志文件前缀expire_logs_days=7 #自动清理 7 天前的log文件,可根据需要修改binlog_format=ROW #选择row模式4.重启mysql数据库
切换到 mysql的 隶属用户：hd-mysql
[root@localhost local]# su hd-mysql
[hd-mysql@localhost etc]$ service mysql start
Starting MySQL. SUCCESS!
重启后，再查看binlog的值，为on，则表示已经开启了。
5.创建远程访问用户，并授权访问
进入mysql的命令模式：
create user 'canal'@'%'IDENTIFIED BY 'boc123'grant all on *.* to 'canal'@'%'flush privileges;mysql> create user ‘canal’@’%’IDENTIFIED BY ‘boc123’;
Query OK, 0 rows affected (0.01 sec)
mysql> grant all on *.* to ‘canal’@’%’;
Query OK, 0 rows affected (0.01 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.02 sec)
mysql>
2.3配置安装canal同步工具
1.软件包下载地址
Releases · alibaba/canal · GitHub
2.上传软件包到服务器
3.解压并修改配置文件
将软件安装到：/usr/local/ 目录下 ，完整路径为 /usr/local/canal 这个目录
[root@localhost local]# mkdir -p canal
[root@localhost local]# cd canal/
[root@localhost canal]# ls
[root@localhost canal]# pwd
/usr/local/canal
[root@localhost canal]# tar -zxvf /root/export/servers/canal.deployer-1.1.6.tar.gz -C .
bin/startup.bat
bin/restart.sh
bin/startup.sh
bin/stop.sh
conf/metrics/
conf/example/
4.修改配置文件
vi conf/example/instance.properties
[root@localhost example]# pwd
/usr/local/canal/conf/example
[root@localhost example]# vi instance.properties
修改内容如下
mysql 数据解析关注的表，Perl正则表达式.
多个正则之间以逗号(,)分隔，转义符需要双斜杠(\\)
常见例子：
1.所有表：.*or.*\\..*
2.canal schema下所有表： canal\\..*
3.canal下的以canal打头的表：canal\\.canal.*
4.canal schema(这里的canal是数据库的名字，test1 为表名)下的一张表：canal.test1
5.多个规则组合使用：canal\\..*,mysql.test1,mysql.test2 (逗号分隔)
注意：此过滤条件只针对row模式的数据有效(ps. mixed/statement因为不解析sql，所以无法准确提取tableName进行过滤)
3.进入bin目录下启动
1.进入到安装目录：/usr/local/canal
2.启动命令:sh bin/startup.sh
[root@localhost canal]# ./bin/startup.sh
cd to /usr/local/canal/bin for workaround relative path
LOG CONFIGURATION : /usr/local/canal/bin/../conf/logback.xml
canal conf : /usr/local/canal/bin/../conf/canal.properties
截图如下
2.4 关闭防火墙
2.5 编写接收java程序
1.项目结构
2.pom文件
4.0.0 org.springframework.boot spring-boot-starter-parent 2.2.1.RELEASE com.ljf canal-demo 1.0-SNAPSHOT canal-demo http://www.example.com UTF-8 1.8 1.8 org.springframework.boot spring-boot-starter-web mysql mysql-connector-java commons-dbutils commons-dbutils 1.7 org.springframework.boot spring-boot-starter-jdbc com.alibaba.otter canal.client 1.1.0 3.配置文件
# 服务端口server.port=10010# 服务名spring.application.name=canal-client-t14# 环境设置：dev、test、prodspring.profiles.active=dev# mysql数据库连接spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driverspring.datasource.url=jdbc:mysql://localhost:3306/xx_db?serverTimezone=GMT%2B8spring.datasource.username=rootspring.datasource.password=cloudiip4.处理类
package com.ljf.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 com.google.protobuf.InvalidProtocolBufferException;import org.apache.commons.dbutils.DbUtils;import org.apache.commons.dbutils.QueryRunner;import org.springframework.stereotype.Component;import javax.annotation.Resource;import javax.sql.DataSource;import java.net.InetSocketAddress;import java.sql.Connection;import java.sql.SQLException;import java.util.Iterator;import java.util.List;import java.util.Queue;import java.util.concurrent.ConcurrentLinkedQueue;@Componentpublic class CanalClient { //sql队列 private Queue SQL_QUEUE = new ConcurrentLinkedQueue(); @Resource private DataSource dataSource; /** * canal入库方法 */ public void run() { CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress("192.168.152.141", 11111), "example", "canal", "boc123"); int batchSize = 1000; try { connector.connect(); connector.subscribe(".*\\..*"); connector.rollback(); try { while (true) { //尝试从master那边拉去数据batchSize条记录，有多少取多少 Message message = connector.getWithoutAck(batchSize); long batchId = message.getId(); int size = message.getEntries().size(); if (batchId == -1 || size == 0) { Thread.sleep(1000); } else { dataHandle(message.getEntries()); } connector.ack(batchId); //当队列里面堆积的sql大于一定数值的时候就模拟执行 if (SQL_QUEUE.size() >= 1) { executeQueueSql(); } } } catch (InterruptedException e) { e.printStackTrace(); } catch (InvalidProtocolBufferException e) { e.printStackTrace(); } } finally { connector.disconnect(); } } /** * 模拟执行队列里面的sql语句 */ public void executeQueueSql() { int size = SQL_QUEUE.size(); for (int i = 0; i " + sql); this.execute(sql.toString()); } } /** * 数据处理 * * @param entrys */ private void dataHandle(List entrys) throws InvalidProtocolBufferException { for (Entry entry : entrys) { if (EntryType.ROWDATA == entry.getEntryType()) { RowChange rowChange = RowChange.parseFrom(entry.getStoreValue()); EventType eventType = rowChange.getEventType(); if (eventType == EventType.DELETE) { saveDeleteSql(entry); } else if (eventType == EventType.UPDATE) { saveUpdateSql(entry); } else if (eventType == EventType.INSERT) { saveInsertSql(entry); } } } } /** * 保存更新语句 * * @param entry */ private void saveUpdateSql(Entry entry) { try { RowChange rowChange = RowChange.parseFrom(entry.getStoreValue()); List rowDatasList = rowChange.getRowDatasList(); for (RowData rowData : rowDatasList) { List newColumnList = rowData.getAfterColumnsList(); StringBuffer sql = new StringBuffer("update " + entry.getHeader().getTableName() + " set "); for (int i = 0; i < newColumnList.size(); i++) { sql.append(" " + newColumnList.get(i).getName() + " = '" + newColumnList.get(i).getValue() + "'"); if (i != newColumnList.size() - 1) { sql.append(","); } } sql.append(" where "); List oldColumnList = rowData.getBeforeColumnsList(); for (Column column : oldColumnList) { if (column.getIsKey()) { //暂时只支持单一主键 sql.append(column.getName() + "=" + column.getValue()); break; } } SQL_QUEUE.add(sql.toString()); } } catch (InvalidProtocolBufferException e) { e.printStackTrace(); } } /** * 保存删除语句 * * @param entry */ private void saveDeleteSql(Entry entry) { try { RowChange rowChange = RowChange.parseFrom(entry.getStoreValue()); List rowDatasList = rowChange.getRowDatasList(); for (RowData rowData : rowDatasList) { List columnList = rowData.getBeforeColumnsList(); StringBuffer sql = new StringBuffer("delete from " + entry.getHeader().getTableName() + " where "); for (Column column : columnList) { if (column.getIsKey()) { //暂时只支持单一主键 sql.append(column.getName() + "=" + column.getValue()); break; } } SQL_QUEUE.add(sql.toString()); } } catch (InvalidProtocolBufferException e) { e.printStackTrace(); } } /** * 保存插入语句 * * @param entry */ private void saveInsertSql(Entry entry) { try { RowChange rowChange = RowChange.parseFrom(entry.getStoreValue()); List rowDatasList = rowChange.getRowDatasList(); for (RowData rowData : rowDatasList) { List columnList = rowData.getAfterColumnsList(); StringBuffer sql = new StringBuffer("insert into " + entry.getHeader().getTableName() + " ("); for (int i = 0; i < columnList.size(); i++) { sql.append(columnList.get(i).getName()); if (i != columnList.size() - 1) { sql.append(","); } } sql.append(") VALUES ("); for (int i = 0; i < columnList.size(); i++) { sql.append("'" + columnList.get(i).getValue() + "'"); if (i != columnList.size() - 1) { sql.append(","); } } sql.append(")"); SQL_QUEUE.add(sql.toString()); } } catch (InvalidProtocolBufferException e) { e.printStackTrace(); } } /** * 入库 * @param sql */ public void execute(String sql) { Connection con = null; try { if(null == sql) return; con = dataSource.getConnection(); QueryRunner qr = new QueryRunner(); int row = qr.execute(con, sql); System.out.println("update: "+ row); } catch (SQLException e) { e.printStackTrace(); } finally { DbUtils.closeQuietly(con); } }}5.启动类
package com.ljf;import com.ljf.canal.CanalClient;import org.springframework.boot.CommandLineRunner;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import javax.annotation.Resource;/** * Hello world! * */@SpringBootApplicationpublic class App implements CommandLineRunner{ @Resource private CanalClient canalClient; public static void main( String[] args ) { System.out.println( "Hello World!" ); SpringApplication.run(App.class, args); } @Override public void run(String... strings) throws Exception { //项目启动，执行canal客户端监听 canalClient.run(); }}6.启动服务
2.6测试验证
1.在目的端的数据库，新建一个同样名字的数据库，同样名字的数据表。
如这里源数据库 xx_db, 数据表tb_student;
目的端：
2.在源表中新增数据
3.在目的库中查看
4.查看console
总结： 可以看到新增数据已经同步过来了！
源代码见: https://gitee.com/jurf-liu/canal-demo.git