ClientSample

ClientSample

直接使用canal.example工程

a. 首先启动Canal Server，可参见QuickStartb.

可以在eclipse里，直接打开com.alibaba.otter.canal.example.SimpleCanalClientTest，直接运行
在工程的example目录下运行命令行：
mvn exec:java -Dexec.mainClass="com.alibaba.otter.canal.example.SimpleCanalClientTest"

下载example包: https://github.com/alibaba/canal/releases，解压缩后，直接运行sh startup.sh脚本c. 触发数据变更d. 在控制台或者logs中查看，可以看到如下信息：

================> binlog[mysql-bin.002579:508882822] , name[retl,xdual] , eventType : UPDATE , executeTime : 1368607728000 , delay : 4270ms
-------> before
ID : 1    update=false
X : 2013-05-15 11:43:42    update=false
-------> after
ID : 1    update=false
X : 2013-05-15 16:48:48    update=true

从头创建工程

依赖配置：

<dependency>
    <groupId>com.alibaba.otter</groupId>
    <artifactId>canal.client</artifactId>
    <version>1.0.12</version>
</dependency>

创建mvn标准工程：

mvn archetype:create -DgroupId=com.alibaba.otter -DartifactId=canal.sample

maven3.0.5以上版本舍弃了create，使用generate生成项目

mvn archetype:generate -DgroupId=com.alibaba.otter -DartifactId=canal.sample

修改pom.xml，添加依赖

ClientSample代码

package com.alibaba.otter.canal.sample;
 
import java.net.InetSocketAddress;
import java.util.List;
 
 
import com.alibaba.otter.canal.client.CanalConnectors;
import com.alibaba.otter.canal.client.CanalConnector;
import com.alibaba.otter.canal.common.utils.AddressUtils;
import com.alibaba.otter.canal.protocol.Message;
import com.alibaba.otter.canal.protocol.CanalEntry.Column;
import com.alibaba.otter.canal.protocol.CanalEntry.Entry;
import com.alibaba.otter.canal.protocol.CanalEntry.EntryType;
import com.alibaba.otter.canal.protocol.CanalEntry.EventType;
import com.alibaba.otter.canal.protocol.CanalEntry.RowChange;
import com.alibaba.otter.canal.protocol.CanalEntry.RowData;
 
 
public class SimpleCanalClientExample {
 
 
public static void main(String args[]) {
    // 创建链接
    CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress(AddressUtils.getHostIp(),
                                                                                        11111), "example", "", "");
    int batchSize = 1000;
    int emptyCount = 0;
    try {
        connector.connect();
        connector.subscribe(".*\\..*");
        connector.rollback();
        int totalEmptyCount = 120;
        while (emptyCount < totalEmptyCount) {
            Message message = connector.getWithoutAck(batchSize); // 获取指定数量的数据
            long batchId = message.getId();
            int size = message.getEntries().size();
            if (batchId == -1 || size == 0) {
                emptyCount++;
                System.out.println("empty count : " + emptyCount);
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                }
            } else {
                emptyCount = 0;
                // System.out.printf("message[batchId=%s,size=%s] \n", batchId, size);
                printEntry(message.getEntries());
            }
            connector.ack(batchId); // 提交确认
            // connector.rollback(batchId); // 处理失败, 回滚数据
        }
        System.out.println("empty too many times, exit");
    } finally {
        connector.disconnect();
    }
}
private static void printEntry(List<Entry> entrys) {
    for (Entry entry : entrys) {
        if (entry.getEntryType() == EntryType.TRANSACTIONBEGIN || entry.getEntryType() == EntryType.TRANSACTIONEND) {
            continue;
        }
        RowChange rowChage = null;
        try {
            rowChage = RowChange.parseFrom(entry.getStoreValue());
        } catch (Exception e) {
            throw new RuntimeException("ERROR ## parser of eromanga-event has an error , data:" + entry.toString(),
                                       e);
        }
        EventType eventType = rowChage.getEventType();
        System.out.println(String.format("================&gt; binlog[%s:%s] , name[%s,%s] , eventType : %s",
                                         entry.getHeader().getLogfileName(), entry.getHeader().getLogfileOffset(),
                                         entry.getHeader().getSchemaName(), entry.getHeader().getTableName(),
                                         eventType));
        for (RowData rowData : rowChage.getRowDatasList()) {
            if (eventType == EventType.DELETE) {
                printColumn(rowData.getBeforeColumnsList());
            } else if (eventType == EventType.INSERT) {
                printColumn(rowData.getAfterColumnsList());
            } else {
                System.out.println("-------&gt; before");
                printColumn(rowData.getBeforeColumnsList());
                System.out.println("-------&gt; after");
                printColumn(rowData.getAfterColumnsList());
            }
        }
    }
}
private static void printColumn(List<Column> columns) {
    for (Column column : columns) {
        System.out.println(column.getName() + " : " + column.getValue() + "    update=" + column.getUpdated());
    }
}
 
 
 
}

运行Client

首先启动Canal Server，可参见QuickStart

启动Canal Client后，可以从控制台从看到类似消息：

empty count : 1
empty count : 2
empty count : 3
empty count : 4

此时代表当前数据库无变更数据

触发数据库变更

mysql> use test;
Database changed
mysql> CREATE TABLE `xdual` (
    ->   `ID` int(11) NOT NULL AUTO_INCREMENT,
    ->   `X` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
    ->   PRIMARY KEY (`ID`)
    -> ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 ;
Query OK, 0 rows affected (0.06 sec)
 
mysql> insert into xdual(id,x) values(null,now());Query OK, 1 row affected (0.06 sec)

可以从控制台中看到：

empty count : 1
empty count : 2
empty count : 3
empty count : 4
================> binlog[mysql-bin.001946:313661577] , name[test,xdual] , eventType : INSERT
ID : 4    update=true
X : 2013-02-05 23:29:46    update=true

最后：

如果需要更详细的exmpale例子，请下载canal当前最新源码包，里面有个example工程，谢谢.

Simple客户端例子：SimpleCanalClientTest
Cluster客户端例子：ClusterCanalClientTest

原文: https://github.com/alibaba/canal/wiki/ClientExample