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This article focuses on "how to read data from Hadoop URL". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor learn "how to read data from Hadoop URL".

1, write code

Import java.io.*

Import java.net.URL

Import org.apache.hadoop.fs.FsUrlStreamHandlerFactory

Import org.apache.hadoop.io.IOUtils

Public class URLCat {

Static {

URL.setURLStreamHandlerFactory (new FsUrlStreamHandlerFactory ())

}

Public static void main (String [] args) throws Exception {

InputStream in = null

Try {

In = new URL (args [0]). OpenStream ()

IOUtils.copyBytes (in, System.out, 4096, false)

} finally {

IOUtils.closeStream (in)

}

}

}

2, compile the Java code

$Hadoopcom.sun.tools.javac.Mian-d classes URLCat.java

/ / then the class files will be generated in the directory of classes

3, package it into a jar package

Jar cf URLCat.jar classes/URLCat.class

/ / then we will get the URLCat.jar, the source is from classes/URLCat.class

4, run the jar package

Hadoop jar URLCat.jar URLCat hdfs://10.10.12.171/input/WordCount/file1

Result:

Hadoop ok

Hadoop fail

Hadoop 2.3

It can be seen that the contents of hdfs://10.10.12.171/input/WordCount/file1 are output to standard output.

At this point, I believe you have a deeper understanding of "how to read data from Hadoop URL". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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