Scala 파일 읽 기,쓰기,콘 솔 작업 방법 예제

25149 단어 Scala읽 기기록 하 다콘 솔 조작
스칼라 파일 읽 기
E 디스크 루트 디 렉 터 리 아래 scalaIO.txt 파일 내용 은 다음 과 같 습 니 다.

파일 읽 기 예제 코드:

 //    
 val file=Source.fromFile("E:\\scalaIO.txt")
 for(line <- file.getLines)
 {
  println(line)
 }
 file.close

설명 1:file=Source.from File("E:\scalaIO.txt"),그 중에서 Source 의 from File()방법 은 import scala.io.Source 소스 패키지 에서 유래 되 었 습 니 다.소스 코드 는 다음 그림 과 같 습 니 다.

file.getLines()는 교체 기-Interator 를 되 돌려 줍 니 다.원본 코드 는 다음 과 같 습 니 다:(scala.io)

스칼라 네트워크 자원 읽 기

 //      
 val webFile=Source.fromURL("http://spark.apache.org")
 webFile.foreach(print)
 webFile.close()
from URL()방법 원본 은 다음 과 같 습 니 다.

 /** same as fromURL(new URL(s))
 */
 def fromURL(s: String)(implicit codec: Codec): BufferedSource =
 fromURL(new URL(s))(codec)
읽 은 네트워크 자원 의 내용 은 다음 과 같 습 니 다.

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 <b>Apache Spark&trade;</b> is a fast and general engine for large-scale data processing.
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 <h2>Speed</h2>

 <p class="lead">
  Run programs up to 100x faster than
  Hadoop MapReduce in memory, or 10x faster on disk.
 </p>

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  Spark has an advanced DAG execution engine that supports cyclic data flow and
  in-memory computing.
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 <h2>Ease of Use</h2>

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  Write applications quickly in Java, Scala, Python, R.
 </p>

 <p>
  Spark offers over 80 high-level operators that make it easy to build parallel apps.
  And you can use it <em>interactively</em>
  from the Scala, Python and R shells.
 </p>
 </div>
 <div class="col-md-5 col-sm-5 col-padded-top col-center">
 <div style="text-align: left; display: inline-block;">
  <div class="code">
  text_file = spark.textFile(<span class="string">"hdfs://..."</span>)<br />
  &nbsp;<br />
  text_file.<span class="sparkop">flatMap</span>(<span class="closure">lambda&nbsp;line:&nbsp;line.split()</span>)<br />
  &nbsp;&nbsp;&nbsp;&nbsp;.<span class="sparkop">map</span>(<span class="closure">lambda word: (word, 1)</span>)<br />
  &nbsp;&nbsp;&nbsp;&nbsp;.<span class="sparkop">reduceByKey</span>(<span class="closure">lambda a, b: a+b</span>)
  </div>
  <div class="caption">Word count in Spark's Python API</div>
 </div>
 <!--
 <div class="code" style="margin-top: 20px; text-align: left; display: inline-block;">
  text_file = spark.textFile(<span class="string">"hdfs://..."</span>)<br/>
  &nbsp;<br/>
  text_file.<span class="sparkop">filter</span>(<span class="closure">lambda line: "ERROR" in line</span>)<br/>
  &nbsp;&nbsp;&nbsp;&nbsp;.<span class="sparkop">count</span>()
 </div>
 -->
 <!--<div class="caption">Word count in Spark</div>-->
 </div>
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 <h2>Generality</h2>

 <p class="lead">
  Combine SQL, streaming, and complex analytics.
 </p>

 <p>
  Spark powers a stack of libraries including
  <a href="/sql/" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >SQL and DataFrames</a>, <a href="/mllib/" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >MLlib</a> for machine learning,
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  You can combine these libraries seamlessly in the same application.
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 <h2>Runs Everywhere</h2>

 <p class="lead">
  Spark runs on Hadoop, Mesos, standalone, or in the cloud. It can access diverse data sources including HDFS, Cassandra, HBase, and S3.
 </p>

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  You can run Spark using its <a href="/docs/latest/spark-standalone.html" rel="external nofollow" >standalone cluster mode</a>, on <a href="/docs/latest/ec2-scripts.html" rel="external nofollow" >EC2</a>, on Hadoop YARN, or on <a href="http://mesos.apache.org" rel="external nofollow" >Apache Mesos</a>.
  Access data in <a href="http://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-hdfs/HdfsUserGuide.html" rel="external nofollow" >HDFS</a>, <a href="http://cassandra.apache.org" rel="external nofollow" >Cassandra</a>, <a href="http://hbase.apache.org" rel="external nofollow" >HBase</a>,
  <a href="http://hive.apache.org" rel="external nofollow" >Hive</a>, <a href="http://tachyon-project.org" rel="external nofollow" >Tachyon</a>, and any Hadoop data source.
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 <h3>Community</h3>

 <p>
  Spark is used at a wide range of organizations to process large datasets.
  You can find example use cases at the <a href="http://spark-summit.org/summit-2013/" rel="external nofollow" >Spark Summit</a>
  conference, or on the
  <a href="https://cwiki.apache.org/confluence/display/SPARK/Powered+By+Spark" rel="external nofollow" rel="external nofollow" >Powered By</a>
  page.
 </p>

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  There are many ways to reach the community:
 </p>
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  <li>Use the <a href="/community.html#mailing-lists" rel="external nofollow" >mailing lists</a> to ask questions.</li>
  <li>In-person events include the <a href="http://www.meetup.com/spark-users/" rel="external nofollow" >Bay Area Spark meetup</a> and
  <a href="http://spark-summit.org/" rel="external nofollow" >Spark Summit</a>.</li>
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  Apache Spark is built by a wide set of developers from over 200 companies.
  Since 2009, more than 800 developers have contributed to Spark!
 </p>

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  The project's
  <a href="https://cwiki.apache.org/confluence/display/SPARK/Committers" rel="external nofollow" rel="external nofollow" >committers</a>
  come from 16 organizations.
 </p>

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  If you'd like to participate in Spark, or contribute to the libraries on top of it, learn
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 <ul class="list-narrow">
  <li><a href="/downloads.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >Download</a> the latest release &mdash; you can run Spark locally on your laptop.</li>
  <li>Read the <a href="/docs/latest/quick-start.html" rel="external nofollow" >quick start guide</a>.</li>
  <li>
  Spark Summit 2014 contained free <a href="http://spark-summit.org/2014/training" rel="external nofollow" >training videos and exercises</a>.
  </li>
  <li>Learn how to <a href="/docs/latest/#launching-on-a-cluster" rel="external nofollow" >deploy</a> Spark on a cluster.</li>
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Process finished with exit code 0

 //      
 val webFile=Source.fromURL("http://www.baidu.com/")
 webFile.foreach(print)
 webFile.close()
중국어 자원 사 이 트 를 읽 고 인 코딩 혼란 문제 가 발생 하면 다음 과 같 습 니 다.(해결 방법 은 스스로 해결 하고 본 고 는 중점 이 아 닙 니 다)

Exception in thread "main" java.nio.charset.MalformedInputException: Input length = 1
이상 이 바로 본 고의 모든 내용 입 니 다.여러분 의 학습 에 도움 이 되 고 저 희 를 많이 응원 해 주 셨 으 면 좋 겠 습 니 다.
SQLServer 에서 확장 이 벤트 를 사용 하여 세 션 단계 의 대기 정보 및 SQLServer 2016 에서 세 션 단계 의 대기 정 보 를 가 져 옵 니 다.
Sql 서버 데이터베이스 버 전 별 기능 비교

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