应用场景
将远程数据库的内容同步到本地库中，这样的话可以做到程序解耦，效率更高。如下图，本地数据库edusta的user表同步远程数据库educenter的users。
使用
测试前置说明：
- 一个本地mysql 端口号3306
- 一个远程mysql 端口号3308
- 版本：mysql8.0
C:\Users\26765>mysql -V mysql Ver 8.0.30 for Win64 on x86_64 (MySQL Community Server - GPL) [root@localhost ~]# docker ps | grep mysql 73ba6154f568 mysql:8.0.28 "docker-entrypoint.s…" 5 hours ago Up 4 hours 33060/tcp, 0.0.0.0:3308->3306/tcp, :::3308->3306/tcp mysql8.0.28
在远程服务器中搭建Canal环境：
检查binlog功能是否有开启
mysql> show variables like 'log_bin'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_bin | OFF | +---------------+-------+ 1 row in set (0.00 sec)
如果显示状态为OFF表示该功能未开启，开启binlog功能
1，修改 mysql 的配置文件 my.cnf vi /etc/my.cnf 追加内容： log-bin=mysql-bin #binlog文件名 binlog_format=ROW #选择row模式 server_id=1 #mysql实例id,不能和canal的slaveId重复 2，重启 mysql： service mysql restart 3，登录 mysql 客户端，查看 log_bin 变量 mysql> show variables like 'log_bin'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_bin | ON| +---------------+-------+ 1 row in set (0.00 sec) ———————————————— 如果显示状态为ON表示该功能已开启
在mysql里面添加以下的相关用户和权限
CREATE USER 'canal'@'%' IDENTIFIED BY 'canal';
GRANT SHOW VIEW, SELECT, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'canal'@'%';
FLUSH PRIVILEGES;
或者查看mysql自带的root是否具有远程操作权限，如果符合以下则也可以使用mysql root账户,本次使用root账户即可
下载Canal
下载地址：
https://github.com/alibaba/canal/releases
下载完传到服务器解压缩
[root@localhost canal]# ls bin canal.deployer-1.1.4.tar.gz conf lib logs
修改配置文件
启动Canal
创建一个新模块和目录结构
引入依赖
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!--mysql--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <dependency> <groupId>commons-dbutils</groupId> <artifactId>commons-dbutils</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>com.alibaba.otter</groupId> <artifactId>canal.client</artifactId> </dependency> </dependencies>
写配置文件，连接本地数据库
# 服务端口 server.port=10001 # 服务名 spring.application.name=canal-client # 环境设置：dev、test、prod spring.profiles.active=dev # mysql数据库连接 spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver spring.datasource.url=jdbc:mysql://localhost:3306/guli?serverTimezone=GMT%2B8 spring.datasource.username=root spring.datasource.password=796321@zy
新建CanalClient
@Component public class CanalClient { //sql队列 private Queue<String> SQL_QUEUE = new ConcurrentLinkedQueue<>(); @Resource private DataSource dataSource; /** * canal入库方法 */ public void run() { CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress("192.168.100.10", 11111), "example", "", ""); 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 < size; i++) { String sql = SQL_QUEUE.poll(); System.out.println("[sql]----> " + sql); this.execute(sql.toString()); } } /** * 数据处理 * * @param entrys */ private void dataHandle(List<Entry> 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<RowData> rowDatasList = rowChange.getRowDatasList(); for (RowData rowData : rowDatasList) { List<Column> 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<Column> 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<RowData> rowDatasList = rowChange.getRowDatasList(); for (RowData rowData : rowDatasList) { List<Column> 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<RowData> rowDatasList = rowChange.getRowDatasList(); for (RowData rowData : rowDatasList) { List<Column> 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); } } }
创建启动类
@SpringBootApplication public class CanalApplication implements CommandLineRunner { @Autowired private CanalClient canalClient; public static void main(String[] args) { SpringApplication.run(CanalApplication.class, args); } @Override public void run(String... args) throws Exception { //项目启动，执行canal客户端监听 canalClient.run(); } }
测试
远程mysql member表添加一条数据
查看本地
