Canal入门使用小结

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.hezy</groupId>
    <artifactId>canal_demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!--canal客户端-->
        <dependency>
            <groupId>top.javatool</groupId>
            <artifactId>canal-spring-boot-starter</artifactId>
            <version>1.2.1-RELEASE</version>
        </dependency>
    </dependencies>

</project>

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.ByteString;
import com.google.protobuf.InvalidProtocolBufferException;

import java.net.InetSocketAddress;
import java.util.HashMap;
import java.util.List;

/**
 * Canal处理器
 * 作用：打印canal服务器监测到的数据
 */
public class CanalHandler {
    public static void main(String[] args) throws InvalidProtocolBufferException {

        // 1.创建连接
        CanalConnector canalConnector = CanalConnectors
                .newSingleConnector(new InetSocketAddress("localhost", 11111), "example", "", "");

        // 2.抓取数据
        while (true) {

            // 3.开始连接
            canalConnector.connect();

            // 4.订阅数据，所有的库和表
            canalConnector.subscribe(".*\\..*");

            // 5.抓取数据，每次抓取100条
            Message message = canalConnector.get(100);

            // 6.获取entry集合
            List<CanalEntry.Entry> entries = message.getEntries();

            // 7.判断是否有数据
            if (entries.size() == 0) {
                System.out.println(">>>暂无数据<<<");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } else {
                // 8.解析数据
                for (CanalEntry.Entry entry : entries) {
                    // 获取表名
                    String tableName = entry.getHeader().getTableName();
                    // 获取操作类型
                    CanalEntry.EntryType entryType = entry.getEntryType();

                    // 判断entryType是否为ROWDATA
                    if (CanalEntry.EntryType.ROWDATA.equals(entryType)) {
                        // 序列化数据
                        ByteString storeValue = entry.getStoreValue();
                        // 反序列化数据
                        CanalEntry.RowChange rowChange = CanalEntry.RowChange.parseFrom(storeValue);

                        // 获取事件类型
                        CanalEntry.EventType eventType = rowChange.getEventType();
                        // 获取具体的数据
                        List<CanalEntry.RowData> rowDatasList = rowChange.getRowDatasList();
                        // 遍历打印
                        for (CanalEntry.RowData rowData : rowDatasList) {
                            // 获取拉取前后的数据
                            List<CanalEntry.Column> beforeColumnsList = rowData.getBeforeColumnsList();
                            List<CanalEntry.Column> afterColumnsList = rowData.getAfterColumnsList();

                            // 用Map存储每条数据
                            HashMap<String, Object> beforeMap = new HashMap<>();
                            HashMap<String, Object> afterMap = new HashMap<>();

                            // 获取不同操作的数据
                            if (CanalEntry.EventType.INSERT.equals(eventType)) {
                                System.out.println("【" + tableName + "】表插入数据");
                                for (CanalEntry.Column column : afterColumnsList) {
                                    afterMap.put(column.getName(), column.getValue());
                                }
                                System.out.println("新增数据：" + afterMap);
                            } else if (CanalEntry.EventType.UPDATE.equals(eventType)) {
                                System.out.println("【" + tableName + "】表更新数据");
                                for (CanalEntry.Column column : beforeColumnsList) {
                                    beforeMap.put(column.getName(), column.getValue());
                                }
                                System.out.println("更新前：" + beforeMap);
                                System.out.println("----");
                                for (CanalEntry.Column column : afterColumnsList) {
                                    afterMap.put(column.getName(), column.getValue());
                                }
                                System.out.println("更新后：" + afterMap);
                            } else if (CanalEntry.EventType.DELETE.equals(eventType)) {
                                System.out.println("【" + tableName + "】表删除数据");
                                for (CanalEntry.Column column : beforeColumnsList) {
                                    beforeMap.put(column.getName(), column.getValue());
                                }
                                System.out.println("被删除的数据：" + beforeMap);
                            }
                        }
                    }
                }
            }
        }
    }
}