hadoop学习笔记之以标准输出方式显示hadoop文件

设置环境变量: .bash_profile 

PATH=$PATH:$HOME/bin:/home/hadoop/jdk1.8.0_111/bin

JAVA_HOME=/home/hadoop/jdk1.8.0_111

export JAVA_HOME

export PATH

设置类目录：vi conf/hadoop-env.sh 

export HADOOP_CLASSPATH=/home/hadoop/hadoop-1.2.1/myclass

创建URLCat.java文件

import org.apache.hadoop.fs.FsUrlStreamHandlerFactory;

import org.apache.hadoop.io.IOUtils;

import java.io.InputStream;

import java.net.URL;

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);

}

}

}

编译URLCat.java

javac -classpath ../hadoop-core-1.2.1.jar URLCat.java

执行

bin/hadoop URLCat hdfs://hadoop01:9000/user/hadoop/in2/test2.txt