1.理解：HdfsWordCount 是從hdfs的檔案讀入流檔案，即制定檔案目錄，每個一段時間掃描該路徑下的檔案，不掃描子目錄下的檔案。

如果有新增加的檔案，則進行流計算

 val ssc = new StreamingContext(sparkConf, Seconds(2))

處理跟前面差不多

2.執行：

輸入：

[email protected]:~/cloud/testByXubo/spark/Streaming/data$ hadoop fs -put 2.txt /xubo/spark/data/Streaming/hdfsWordCount/
[email protected]:~/cloud/testByXubo/spark/Streaming/data$ hadoop fs -put 3.txt /xubo/spark/data/Streaming/hdfsWordCount/
 

[email protected]:~/cloud/testByXubo/spark/Streaming/data$ cat 3.txt 
hello world
hello world
hello world
hello world
hello world
hello world
hello world
a
a
a
a
a
a
a b b b 

輸出：

16/04/26 21:26:06 INFO scheduler.DAGScheduler: Job 19 finished: print at HdfsWordCount.scala:52, took 0.023056 s
-------------------------------------------
Time: 1461677166000 ms
-------------------------------------------
(hello,1)
(world,1)
 

-------------------------------------------
Time: 1461677550000 ms
-------------------------------------------
(b,3)
(hello,7)
(world,7)
(a,7)

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
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 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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 */

// scalastyle:off println
package org.apache.spark.Streaming.learning

import org.apache.spark.SparkConf
import org.apache.spark.streaming.{Seconds, StreamingContext}
import org.apache.spark.streaming.dstream.DStream.toPairDStreamFunctions

/**
 * Counts words in new text files created in the given directory
 * Usage: HdfsWordCount <directory>
 *   <directory> is the directory that Spark Streaming will use to find and read new text files.
 *
 * To run this on your local machine on directory `localdir`, run this example
 *    $ bin/run-example \
 *       org.apache.spark.examples.streaming.HdfsWordCount localdir
 *
 * Then create a text file in `localdir` and the words in the file will get counted.
 */
object HdfsWordCount {
  def main(args: Array[String]) {
    if (args.length < 1) {
      System.err.println("Usage: HdfsWordCount <directory>")
      System.exit(1)
    }

    StreamingExamples.setStreamingLogLevels()
    val sparkConf = new SparkConf().setAppName("HdfsWordCount")
    // Create the context
    val ssc = new StreamingContext(sparkConf, Seconds(2))

    // Create the FileInputDStream on the directory and use the
    // stream to count words in new files created
    val lines = ssc.textFileStream(args(0))
    val words = lines.flatMap(_.split(" "))
    val wordCounts = words.map(x => (x, 1)).reduceByKey(_ + _)
    wordCounts.print()
    ssc.start()
    ssc.awaitTermination()
  }
}
// scalastyle:on println