Canal數據同步工具

一、Canal介紹

1、應用場景
在前面的統計分析功能中，我們採取了服務調用獲取統計數據，這樣耦合度高，效率相對較低，目前我採取另一種實現方式，通過實時同步數據庫表的方式實現，例如我們要統計每天註冊與登錄人數，我們只需把會員表同步到統計庫中，實現本地統計就可以了，這樣效率更高，耦合度更低，Canal就是一個很好的數據庫同步工具。canal是阿里巴巴旗下的一款開源項目，純Java開發。基於數據庫增量日誌解析，提供增量數據訂閱&消費，目前主要支持了MySQL。

2、Canal環境搭建

canal的原理是基於mysql binlog技術，所以這裏一定需要開啓mysql的binlog寫入功能
開啓mysql服務： service mysql start
（1）檢查binlog功能是否有開啓

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

（2）如果顯示狀態爲OFF表示該功能未開啓，開啓binlog功能

1，修改 mysql 的配置文件 my.cnf
vi /etc/my.cnf 
追加內容：
log-bin=mysql-bin     #binlog文件名
binlog_format=ROW     #選擇row模式
server_id=1           #mysql實例id,不能和canal的slaveId重複

2，重啓 mysql：
service mysql restart	

3，登錄 mysql 客戶端，查看 log_bin 變量
mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin       | ON|
+---------------+-------+
1 row in set (0.00 sec)
————————————————
如果顯示狀態爲ON表示該功能已開啓

（3）在mysql裏面添加以下的相關用戶和權限

CREATE USER 'canal'@'%' IDENTIFIED BY 'canal';
GRANT SHOW VIEW, SELECT, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'canal'@'%';
FLUSH PRIVILEGES;

3、下載安裝Canal服務
下載地址：

https://github.com/alibaba/canal/releases

（1）下載之後，放到目錄中，解壓文件

cd /usr/local/canal

canal.deployer-1.1.4.tar.gz

tar zxvf canal.deployer-1.1.4.tar.gz

（2）修改配置文件

vi conf/example/instance.properties

#需要改成自己的數據庫信息
canal.instance.master.address=192.168.44.132:3306

#需要改成自己的數據庫用戶名與密碼

canal.instance.dbUsername=canal
canal.instance.dbPassword=canal

#需要改成同步的數據庫表規則，例如只是同步一下表
#canal.instance.filter.regex=.*\\..*
canal.instance.filter.regex=guli_ucenter.ucenter_member

注：

*mysql 數據解析關注的表，Perl正則表達式.多個正則之間以逗號(,)分隔，轉義符需要雙斜槓(\) 常見例子：

1. 所有表：.* or .\…
2. canal schema下所有表： canal\…*
3. canal下的以canal打頭的表：canal\.canal.*
4. canal schema下的一張表：canal.test1
5. 多個規則組合使用：canal\…,mysql.test1,mysql.test2 (逗號分隔)
   注意：此過濾條件只針對row模式的數據有效(ps. mixed/statement因爲不解析sql，所以無法準確提取tableName進行過濾)

（3）進入bin目錄下啓動

sh bin/startup.sh

二、創建canal_client模塊

1、在parent下創建canal_client模塊
2、引入相關依賴

<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>

3、創建application.properties配置文件

# 服務端口
server.port=10000
# 服務名
spring.application.name=canal-client

# 環境設置：dev、test、prod
spring.profiles.active=dev

# mysql數據庫連接
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test?serverTimezone=GMT%2B8
spring.datasource.username=root
spring.datasource.password=root

4、編寫canal客戶端類

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隊列
    private Queue<String> SQL_QUEUE = new ConcurrentLinkedQueue<>();

    @Resource
    private DataSource dataSource;

    /**
     * canal入庫方法
     */
    public void run() {

        CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress("192.168.44.132",
                11111), "example", "", "");
        int batchSize = 1000;
        try {
            connector.connect();
            connector.subscribe(".*\\..*");
            connector.rollback();
            try {
                while (true) {
                    //嘗試從master那邊拉去數據batchSize條記錄，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);

                    //當隊列裏面堆積的sql大於一定數值的時候就模擬執行
                    if (SQL_QUEUE.size() >= 1) {
                        executeQueueSql();
                    }
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (InvalidProtocolBufferException e) {
                e.printStackTrace();
            }
        } finally {
            connector.disconnect();
        }
    }

    /**
     * 模擬執行隊列裏面的sql語句
     */
    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());
        }
    }

    /**
     * 數據處理
     *
     * @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);
                }
            }
        }
    }

    /**
     * 保存更新語句
     *
     * @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()) {
                        //暫時只支持單一主鍵
                        sql.append(column.getName() + "=" + column.getValue());
                        break;
                    }
                }
                SQL_QUEUE.add(sql.toString());
            }
        } catch (InvalidProtocolBufferException e) {
            e.printStackTrace();
        }
    }

    /**
     * 保存刪除語句
     *
     * @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()) {
                        //暫時只支持單一主鍵
                        sql.append(column.getName() + "=" + column.getValue());
                        break;
                    }
                }
                SQL_QUEUE.add(sql.toString());
            }
        } catch (InvalidProtocolBufferException e) {
            e.printStackTrace();
        }
    }

    /**
     * 保存插入語句
     *
     * @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();
        }
    }

    /**
     * 入庫
     * @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、創建啓動類

@SpringBootApplication
public class CanalApplication implements CommandLineRunner {
    @Resource
    private CanalClient canalClient;

    public static void main(String[] args) {
        SpringApplication.run(CanalApplication.class, args);
    }

    @Override
    public void run(String... strings) throws Exception {
        //項目啓動，執行canal客戶端監聽
        canalClient.run();
    }
}