hadoop第一个例子

 

Java.io.URL

1、编写java程序

package com.company;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import org.apache.hadoop.fs.FsUrlStreamHandlerFactory;
import org.apache.hadoop.io.IOUtils;

public class Main {
    static {
        URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory());
    }

    public static void main(String[] args) throws MalformedURLException,IOException {
        InputStream in=null;
        try{
            in = new URL(args[0]).openStream();
            IOUtils.copyBytes(in,System.out,4096,false);
        }finally {
            IOUtils.closeStream(in);
        }
    }
}

2、打包为javaWrkspace.jar

3、simon@simon-Lenovo-G400:~/software/hadoop$

bin/hadoop jar /home/simon/javaWrkspace/out/artifacts/javaWrkspace_jar/javaWrkspace.jar  hdfs://localhost:9000/test/hello

 

org.apache.hadoop.fs.FileSystem

1、

import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
public class hdfsclient {
    public static void main(String[] args) throws IOException{
        String uri="hdfs://localhost:9000/test/hello";
        Configuration conf=new Configuration();
        FileSystem fs = FileSystem.get(URI.create(uri),conf);
        InputStream in=null;
        try{
            in = fs.open(new Path(uri));
            IOUtils.copyBytes(in,System.out,4096,false);
        }finally {
            IOUtils.closeStream(in);
        }
    }
}

2、打包为javaWrkspace.jar

3、simon@simon-Lenovo-G400:~/software/hadoop$

bin/hadoop jar /home/simon/javaWrkspace/out/artifacts/javaWrkspace_jar2/javaWrkspace.jar  hdfsclient