MySQL创建存储offset的表格

mysql> use test
mysql> create table hlw_offset(
        topic varchar(32),
        groupid varchar(50),
        partitions int,
        fromoffset bigint,
        untiloffset bigint,
        primary key(topic,groupid,partitions)
        );

Maven依赖包

<scala.version>2.11.8</scala.version>
<spark.version>2.3.1</spark.version>
<scalikejdbc.version>2.5.0</scalikejdbc.version>
--------------------------------------------------
<dependency>
    <groupId>org.scala-lang</groupId>
    <artifactId>scala-library</artifactId>
    <version>${scala.version}</version>
</dependency>
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-core_2.11</artifactId>
    <version>${spark.version}</version>
</dependency>
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-sql_2.11</artifactId>
    <version>${spark.version}</version>
</dependency>
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-streaming_2.11</artifactId>
    <version>${spark.version}</version>
</dependency>
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-streaming-kafka-0-8_2.11</artifactId>
    <version>${spark.version}</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.27</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.scalikejdbc/scalikejdbc -->
<dependency>
    <groupId>org.scalikejdbc</groupId>
    <artifactId>scalikejdbc_2.11</artifactId>
    <version>2.5.0</version>
</dependency>
<dependency>
    <groupId>org.scalikejdbc</groupId>
    <artifactId>scalikejdbc-config_2.11</artifactId>
    <version>2.5.0</version>
</dependency>
<dependency>
    <groupId>com.typesafe</groupId>
    <artifactId>config</artifactId>
    <version>1.3.0</version>
</dependency>
<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.5</version>
</dependency>

实现思路

1)StreamingContext
2)从kafka中获取数据(从外部存储获取offset-->根据offset获取kafka中的数据)
3)根据业务进行逻辑处理
4)将处理结果存到外部存储中--保存offset
5)启动程序,等待程序结束

代码实现

  1. SparkStreaming主体代码如下

    import kafka.common.TopicAndPartition
    import kafka.message.MessageAndMetadata
    import kafka.serializer.StringDecoder
    import org.apache.spark.SparkConf
    import org.apache.spark.streaming.kafka.{HasOffsetRanges, KafkaUtils}
    import org.apache.spark.streaming.{Seconds, StreamingContext}
    import scalikejdbc._
    import scalikejdbc.config._
    object JDBCOffsetApp {
     def main(args: Array[String]): Unit = {
       //创建SparkStreaming入口
       val conf = new SparkConf().setMaster("local[2]").setAppName("JDBCOffsetApp")
       val ssc = new StreamingContext(conf,Seconds(5))
       //kafka消费主题
       val topics = ValueUtils.getStringValue("kafka.topics").split(",").toSet
       //kafka参数
       //这里应用了自定义的ValueUtils工具类,来获取application.conf里的参数,方便后期修改
       val kafkaParams = Map[String,String](
         "metadata.broker.list"->ValueUtils.getStringValue("metadata.broker.list"),
         "auto.offset.reset"->ValueUtils.getStringValue("auto.offset.reset"),
         "group.id"->ValueUtils.getStringValue("group.id")
       )
       //先使用scalikejdbc从MySQL数据库中读取offset信息
       //+------------+------------------+------------+------------+-------------+
       //| topic      | groupid          | partitions | fromoffset | untiloffset |
       //+------------+------------------+------------+------------+-------------+
       //MySQL表结构如上,将“topic”,“partitions”,“untiloffset”列读取出来
       //组成 fromOffsets: Map[TopicAndPartition, Long],后面createDirectStream用到
       DBs.setup()
       val fromOffset = DB.readOnly( implicit session => {
         SQL("select * from hlw_offset").map(rs => {
           (TopicAndPartition(rs.string("topic"),rs.int("partitions")),rs.long("untiloffset"))
         }).list().apply()
       }).toMap
       //如果MySQL表中没有offset信息,就从0开始消费;如果有,就从已经存在的offset开始消费
         val messages = if (fromOffset.isEmpty) {
           println("从头开始消费...")
           KafkaUtils.createDirectStream[String,String,StringDecoder,StringDecoder](ssc,kafkaParams,topics)
         } else {
           println("从已存在记录开始消费...")
           val messageHandler = (mm:MessageAndMetadata[String,String]) => (mm.key(),mm.message())
           KafkaUtils.createDirectStream[String,String,StringDecoder,StringDecoder,(String,String)](ssc,kafkaParams,fromOffset,messageHandler)
         }
         messages.foreachRDD(rdd=>{
           if(!rdd.isEmpty()){
             //输出rdd的数据量
             println("数据统计记录为:"+rdd.count())
             //官方案例给出的获得rdd offset信息的方法,offsetRanges是由一系列offsetRange组成的数组
    //          trait HasOffsetRanges {
    //            def offsetRanges: Array[OffsetRange]
    //          }
             val offsetRanges = rdd.asInstanceOf[HasOffsetRanges].offsetRanges
             offsetRanges.foreach(x => {
               //输出每次消费的主题,分区,开始偏移量和结束偏移量
               println(s"---${x.topic},${x.partition},${x.fromOffset},${x.untilOffset}---")
              //将最新的偏移量信息保存到MySQL表中
               DB.autoCommit( implicit session => {
                 SQL("replace into hlw_offset(topic,groupid,partitions,fromoffset,untiloffset) values (?,?,?,?,?)")
               .bind(x.topic,ValueUtils.getStringValue("group.id"),x.partition,x.fromOffset,x.untilOffset)
                 .update().apply()
               })
             })
           }
         })
       ssc.start()
       ssc.awaitTermination()
     }
    }
  2. 自定义的ValueUtils工具类如下

    import com.typesafe.config.ConfigFactory
    import org.apache.commons.lang3.StringUtils
    object ValueUtils {
    val load = ConfigFactory.load()
     def getStringValue(key:String, defaultValue:String="") = {
    val value = load.getString(key)
       if(StringUtils.isNotEmpty(value)) {
         value
       } else {
         defaultValue
       }
     }
    }
  3. application.conf内容如下

    metadata.broker.list = "192.168.137.251:9092"
    auto.offset.reset = "smallest"
    group.id = "hlw_offset_group"
    kafka.topics = "hlw_offset"
    serializer.class = "kafka.serializer.StringEncoder"
    request.required.acks = "1"
    # JDBC settings
    db.default.driver = "com.mysql.jdbc.Driver"
    db.default.url="jdbc:mysql://hadoop000:3306/test"
    db.default.user="root"
    db.default.password="123456"
  4. 自定义kafka producer

    import java.util.{Date, Properties}
    import kafka.producer.{KeyedMessage, Producer, ProducerConfig}
    object KafkaProducer {
     def main(args: Array[String]): Unit = {
       val properties = new Properties()
       properties.put("serializer.class",ValueUtils.getStringValue("serializer.class"))
       properties.put("metadata.broker.list",ValueUtils.getStringValue("metadata.broker.list"))
       properties.put("request.required.acks",ValueUtils.getStringValue("request.required.acks"))
       val producerConfig = new ProducerConfig(properties)
       val producer = new Producer[String,String](producerConfig)
       val topic = ValueUtils.getStringValue("kafka.topics")
       //每次产生100条数据
       var i = 0
       for (i <- 1 to 100) {
         val runtimes = new Date().toString
        val messages = new KeyedMessage[String, String](topic,i+"","hlw: "+runtimes)
         producer.send(messages)
       }
       println("数据发送完毕...")
     }
    }

测试

  1. 启动kafka服务,并创建主题

    [hadoop@hadoop000 bin]$ ./kafka-server-start.sh -daemon /home/hadoop/app/kafka_2.11-0.10.0.1/config/server.properties
    [hadoop@hadoop000 bin]$ ./kafka-topics.sh --list --zookeeper localhost:2181/kafka
    [hadoop@hadoop000 bin]$ ./kafka-topics.sh --create --zookeeper localhost:2181/kafka --replication-factor 1 --partitions 1 --topic hlw_offset
  2. 测试前查看MySQL中offset表,刚开始是个空表

    mysql> select * from hlw_offset;
    Empty set (0.00 sec)
  3. 通过kafka producer产生500条数据

  4. 启动SparkStreaming程序

    //控制台输出结果:
    从头开始消费...
    数据统计记录为:500
    ---hlw_offset,0,0,500---
查看MySQL表,offset记录成功

mysql> select * from hlw_offset;
+------------+------------------+------------+------------+-------------+
| topic      | groupid          | partitions | fromoffset | untiloffset |
+------------+------------------+------------+------------+-------------+
| hlw_offset | hlw_offset_group |          0 |          0 |         500 |
+------------+------------------+------------+------------+-------------+
  1. 关闭SparkStreaming程序,再使用kafka producer生产300条数据,再次启动spark程序(如果spark从500开始消费,说明成功读取了offset,做到了只读取一次语义)

    //控制台结果输出:
    从已存在记录开始消费...
    数据统计记录为:300
    ---hlw_offset,0,500,800---
  2. 查看更新后的offset MySQL数据

    mysql> select * from hlw_offset;
    +------------+------------------+------------+------------+-------------+
    | topic      | groupid          | partitions | fromoffset | untiloffset |
    +------------+------------------+------------+------------+-------------+
    | hlw_offset | hlw_offset_group |          0 |        500 |         800 |
    +------------+------------------+------------+------------+-------------+