spark计算用户访问学科子网页的top3
项目说明:附件为要计算数据的demo。点击打开链接
利用spark的缓存机制,读取需要筛选的数据,自定义一个分区器,将不同的学科数据分别放到一个分区器中,并且根据指定的学科,取出点击量前三的数据,并写入文件。
具体程序如下:
1、项目主程序:
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package cn.allengao.Location
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import java.net.URL
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import org.apache.spark.rdd.RDD
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import org.apache.spark.{HashPartitioner, SparkConf, SparkContext}
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/**
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* class_name:
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* package:
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* describe: 缓存机制,自定义一个分区器,根据指定的学科, 取出点击量前三的,按照每种学科数据放到不同的分区器里
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* creat_user: Allen Gao
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* creat_date: 2018/1/30
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* creat_time: 11:21
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**/
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object AdvUrlCount {
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def main(args: Array[String]) {
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//从数据库中加载规则
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// val arr = Array("java.learn.com", "php.learn.com", "net.learn.com")
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val conf = new SparkConf().setAppName("AdvUrlCount").setMaster("local[2]")
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val sc = new SparkContext(conf)
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//获取数据
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val file = sc.textFile("j://information/learn.log")
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//提取出url并生成一个元祖,rdd1将数据切分,元组中放的是(URL, 1)
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val urlAndOne = file.map(line => {
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val fields = line.split("\t")
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val url = fields(1)
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(url, 1)
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})
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//把相同的url进行聚合
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val sumedUrl = urlAndOne.reduceByKey(_ + _)
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//获取学科信息缓存,提高运行效率
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val cachedProject = sumedUrl.map(x => {
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val url = x._1
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val project = new URL(url).getHost
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val count = x._2
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(project, (url, count))
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}).cache()
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//调用Spark自带的分区器此时会发生哈希碰撞,会有数据倾斜问题产生,需要自定义分区器
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// val res = cachedProject.partitionBy(new HashPartitioner(3))
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// res.saveAsTextFile("j://information//out")
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//得到所有学科
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val projects = cachedProject.keys.distinct().collect()
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//调用自定义分区器并得到分区号
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val partitioner = new ProjectPartitioner(projects)
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//分区
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val partitioned: RDD[(String, (String, Int))] = cachedProject.partitionBy(partitioner)
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//对每个分区的数据进行排序并取top3
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val res = partitioned.mapPartitions(it => {
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it.toList.sortBy(_._2._2).reverse.take(3).iterator
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})
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res.saveAsTextFile("j://information//out1")
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sc.stop()
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}
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}
2、自定义分区器:
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package cn.allengao.Location
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import org.apache.spark.Partitioner
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import scala.collection.mutable
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class ProjectPartitioner(projects: Array[String]) extends Partitioner {
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//用来存放学科和分区号
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private val projectsAndPartNum = new mutable.HashMap[String,Int]()
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//计数器,用于指定分区号
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var n = 0
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for(pro<-projects){
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projectsAndPartNum += (pro -> n)
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n += 1
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}
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//得到分区数
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override def numPartitions = projects.length
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//得到分区号
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override def getPartition(key: Any) = {
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projectsAndPartNum.getOrElse(key.toString,0)
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}
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}
运行结果: