canal 数据同步客户端代码实现

引入相关依赖

<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>

创建配置文件

# 服务端口
server.port=10000
# 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&characterEncoding=utf-8
spring.datasource.username=root
spring.datasource.password=root

Canal环境搭建

需要先登录mysql数据库，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，那么这个时候就需要到my.ini里面进行相关配置了，在原来的my.ini(my.cnf)配置底部插入以下内容：

server-id=192
log-bin=mysql-bin
binlog_format = ROW

当再次通过客户端查看log_bin状态为ON的时候，就表示binlog已经开启：

mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin       | ON    |
+---------------+-------+
1 row in set (0.00 sec)

然后在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;

开启之后，我们可以前往canal的官方地址进行相应版本的安装包进行下载：
https://github.com/alibaba/canal/releases

下载好指定的版本之后，找到里面的bin目录底下的startup脚本，启动。

首先是导入相应的依赖文件：

<dependency>
    <groupId>com.alibaba.otter</groupId>
    <artifactId>canal.client</artifactId>
    <version>1.1.0</version>
</dependency>

编写客户端类

开启canal的远程监听，当size大于0时，说明数据有变化，那么执行数据处理，有三种类型的数据处理，包括删除，修改，新增，每种数据处理都对应这特有的方法，而三种方法思路相同，都是将改变的数据拼接成对应的sql语句，然后放入队列中，当队列的大小大于0时就执行对应的方法，方法就是从队列中取出sql语句，然后把语句做执行，最终会在本地库中同步改变的数据。

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;
 
@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("192.168.235.130",
                11111), "example", "", "");
        int batchSize = 1000;
        try {
            connector.connect();
            connector.subscribe("guli.members");
            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);
        }
    }
}

修改启动类

实现一个接口，使得启动类启动时去调用canal客户端进行监听。

import com.renzhe.canal.client.CanalClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
 
@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();
    }
}

https://www.cnblogs.com/javazhiyin/archive/2019/05/09/10836846.html

https://www.jianshu.com/p/9677ca6ca34e

故乡明