Canal环境搭建

 canal的原理是基于mysql binlog技术，所以这里一定需要开启mysql的binlog写入功能。
 开启mysql服务： service mysql start （或者 systemctl start mysqld.service）

1. 检查binlog功能是否有开启

Binlog的三种基本类型分别为：
 STATEMENT模式只记录了sql语句，但是没有记录上下文信息，在进行数据恢复的时候可能会导致数据的丢失情况
 ROW模式除了记录sql语句之外，还会记录每个字段的变化情况，能够清楚的记录每行数据的变化历史，但是会占用较多的空间，需要使用mysqlbinlog工具进行查看。
 MIX模式比较灵活的记录，例如说当遇到了表结构变更的时候，就会记录为statement模式。当遇到了数据更新或者删除情况下就会变为row模式

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

2.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

3.如果显示状态为OFF表示该功能未开启，开启binlog功能在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;

下载安装Canal服务

 下载地址：
 https://github.com/alibaba/canal/releases

1.下载之后，放到目录中，解压文件

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
#需要改成自己的数据库信息
canal.instance.master.address=192.168.44.132:3306
#需要改成自己的数据库用户名与密码
canal.instance.dbUsername=canal
canal.instance.dbPassword=canal
#需要改成同步的数据库表规则，例如只是同步一下表
#canal.instance.filter.regex=.*\\..*
canal.instance.filter.regex=guli_ucenter.ucenter_member

注：
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

sh bin/startup.sh

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application.properties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
spring.datasource.username=root
spring.datasource.password=root

编写canal客户端类

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("192.168.44.132",
                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 {
    @Resource
    private CanalClient canalClient;

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

    @Override
    public void run(String... strings) throws Exception {
        //项目启动，执行canal客户端监听
        canalClient.run();
    }
}