1、需求：动态监控mysql中gmall2数据库的order_info数据表，将变化的信息转成json字符串存储到kafka中，具体实现如下：

CanalClient —— 监控 order_info 单表的代码

package com.zyj.gmall.canal

import java.net.{InetSocketAddress, SocketAddress}
import java.util

import com.alibaba.fastjson.JSONObject
import com.alibaba.otter.canal.client.CanalConnectors
import com.alibaba.otter.canal.protocol.CanalEntry
import com.alibaba.otter.canal.protocol.CanalEntry.{EventType, RowChange}
import com.zyj.gmall.common.Constant

import scala.collection.JavaConversions._

object CanalClient {

  def main(args: Array[String]): Unit = {

    //1. 连接到canal
    val address = new InetSocketAddress("hadoop103", 11111)
    val connector = CanalConnectors.newSingleConnector(address, "example", "", "")
    connector.connect() //连接
    //1.1 订阅数据 gmall2.* 表示gmall2数据下所有的表
    connector.subscribe("gmall2.*")

    //2.读数据，解析数据
    while (true) { // 2.1 使用循环的方式持续的从canal读取数据
      val msg = connector.get(100) // 2.2 一次从canal拉取最多100条sql数据引起的变化
      //2.3 一个entry封装一条sql的变化结果  ，做非空判断
      val entriesOption = if (msg != null) Some(msg.getEntries) else None
      if (entriesOption.isDefined && entriesOption.get.nonEmpty) {
        val entries = entriesOption.get
        for (entry <- entries) {
          //2.4 从每个entry获取一个storeValue
          val storeValue = entry.getStoreValue
          //2.5 把storeValue解析出来rowChange
          val rowChange = RowChange.parseFrom(storeValue)
          //2.6 一个storeValue中有多个RowData，每个RowData表示一行数据的变化
          val rowDatas = rowChange.getRowDatasList
          //2.7 解析rowDatas中的每行的每列数据
          handleDate(entry.getHeader.getTableName, rowDatas, rowChange.getEventType)
        }
      } else {
        println("没有拉取到数据，2秒后重试。。。")
        Thread.sleep(2000)
      }
    }

    // 处理rowData数据
    def handleDate(tableName: String,
                   rowDatas: util.List[CanalEntry.RowData],
                   eventType: CanalEntry.EventType): Unit = {
      if ("order_info" == tableName && eventType == EventType.INSERT && rowDatas != null && rowDatas.nonEmpty) {
        for (rowData <- rowDatas) {
          val result = new JSONObject()
          //1. 一行所有的变化后的列
          val columnsList = rowData.getAfterColumnsList
          //2. 一行数据将来在kafka中，应该房一样，多列中封装一个json字符串
          for (column <- columnsList) {
            val key = column.getName // 列名
            val value = column.getValue // 列值
            result.put(key, value)
          }
          //3.把数据转成json字符串写入到kafka中，{列名：列值，列名：列值，....}
          val content = result.toJSONString
          println(content)
          MyKafkaUtil.send(Constant.TOPIC_ORDER_INFO, content)
        }
      }
    }

  }
}

CanalClient —— 监控 order_info 和 order_detail 多表的代码，对代码做封装

package com.zyj.gmall.canal

import java.net.{InetSocketAddress, SocketAddress}
import java.util

import com.alibaba.fastjson.JSONObject
import com.alibaba.otter.canal.client.CanalConnectors
import com.alibaba.otter.canal.protocol.CanalEntry
import com.alibaba.otter.canal.protocol.CanalEntry.{EventType, RowChange}
import com.zyj.gmall.common.Constant

import scala.collection.JavaConversions._

object CanalClient {

  def main(args: Array[String]): Unit = {

    //1. 连接到canal
    val address = new InetSocketAddress("hadoop103", 11111)
    val connector = CanalConnectors.newSingleConnector(address, "example", "", "")
    connector.connect() //连接
    //1.1 订阅数据 gmall2.* 表示gmall2数据下所有的表
    connector.subscribe("gmall2.*")

    //2.读数据，解析数据
    while (true) { // 2.1 使用循环的方式持续的从canal读取数据
      val msg = connector.get(100) // 2.2 一次从canal拉取最多100条sql数据引起的变化
      //2.3 一个entry封装一条sql的变化结果  ，做非空判断
      val entriesOption = if (msg != null) Some(msg.getEntries) else None
      if (entriesOption.isDefined && entriesOption.get.nonEmpty) {
        val entries = entriesOption.get
        for (entry <- entries) {
          //2.4 从每个entry获取一个storeValue
          val storeValue = entry.getStoreValue
          //2.5 把storeValue解析出来rowChange
          val rowChange = RowChange.parseFrom(storeValue)
          //2.6 一个storeValue中有多个RowData，每个RowData表示一行数据的变化
          val rowDatas = rowChange.getRowDatasList
          //2.7 解析rowDatas中的每行的每列数据
          handleDate(entry.getHeader.getTableName, rowDatas, rowChange.getEventType)
        }
      } else {
        println("没有拉取到数据，2秒后重试。。。")
        Thread.sleep(2000)
      }
    }

    // 处理rowData数据
    def handleDate(tableName: String,
                   rowDatas: util.List[CanalEntry.RowData],
                   eventType: CanalEntry.EventType): Unit = {
      if ("order_info" == tableName && eventType == EventType.INSERT && rowDatas != null && rowDatas.nonEmpty) {

        sendToKafka(Constant.TOPIC_ORDER_INFO, rowDatas)

      } else if ("order_detail" == tableName && eventType == EventType.INSERT && rowDatas != null && rowDatas.nonEmpty) {

        sendToKafka(Constant.TOPIC_ORDER_DETAIL, rowDatas)

      }
    }

  }

  // 把数据发送到kafka
  private def sendToKafka(topic: String, rowDatas: util.List[CanalEntry.RowData]) = {
    for (rowData <- rowDatas) {
      val result = new JSONObject()
      //1. 一行所有的变化后的列
      val columnsList = rowData.getAfterColumnsList
      //2. 一行数据将来在kafka中，应该房一样，多列中封装一个json字符串
      for (column <- columnsList) {
        val key = column.getName // 列名
        val value = column.getValue // 列值
        result.put(key, value)
      }
      //3.把数据转成json字符串写入到kafka中，{列名：列值，列名：列值，....}
      val content = result.toJSONString
      println(content)
      MyKafkaUtil.send(topic, content)
    }
  }
}

 MyKafkaUtil

package com.zyj.gmall.canal

import java.util.Properties

import org.apache.kafka.clients.producer.{KafkaProducer, ProducerConfig, ProducerRecord}

object MyKafkaUtil {

  val prop = new Properties()

  prop.put("bootstrap.servers", "hadoop102:9092,hadoop103:9092,hadoop104:9092")
  prop.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer")
  prop.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer")

  val producer = new KafkaProducer[String, String](prop)

  def send(topic: String, content: String) = {

    producer.send(new ProducerRecord[String, String](topic, content))

  }

}

pom (引用的父模块中fastjson依赖)

<?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">
    <parent>
        <artifactId>gmall1015</artifactId>
        <groupId>com.zyj.gmall</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>gmall-canal</artifactId>

    <dependencies>

        <!--canal 客户端, 从 canal 服务器读取数据-->
        <dependency>
            <groupId>com.alibaba.otter</groupId>
            <artifactId>canal.client</artifactId>
            <version>1.1.2</version>
        </dependency>

        <!-- kafka 客户端 -->
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-clients</artifactId>
            <version>0.11.0.2</version>
        </dependency>

        <dependency>
            <groupId>com.zyj.gmall</groupId>
            <artifactId>gmall-common</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

    </dependencies>

</project>