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tar -zxvf jdk-8u112-linux-x64.tar.gz
tar -zxvf hadoop-2.7.3.tar.gz

mv jdk1.8.0_112 jdk
mv hadoop-2.7.3 hadoop

vi /etc/profile.d/hadoop-eco.sh

JAVA_HOME=/opt/jdk
PATH=$JAVA_HOME/bin:$PATH
HADOOP_HOME=/opt/hadoop
PATH=$HADOOP_HOME/bin:$HADOOP_HOME/sbin:$PATH

ssh-keygen -t rsa

ssh-copy-id -i root@localhost

ssh root@localhost

exit

mkdir -p /opt/hadoop-record/name
mkdir -p /opt/hadoop-record/secondary
mkdir -p /opt/hadoop-record/data
mkdir -p /opt/hadoop-record/tmp
ls /opt/hadoop-record/

source /etc/profile.d/hadoop-eco.sh
java -version

hdfs namenode -format
start-all.sh
jps

systemctl stop firewalld

    <dependencies>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>2.7.3</version>
        </dependency>
    </dependencies>

package com.item.test;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

import java.io.IOException;

public class MapAction extends Mapper<LongWritable, Text, Text, LongWritable> {
    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        char[] split = value.toString().toCharArray();
        for (char s : split) {
            context.write(new Text(s+""), new LongWritable(1));
        }
    }
}

package com.item.test;


import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class ReduceAction extends Reducer<Text, LongWritable, Text, LongWritable> {
    @Override
    protected void reduce(Text key, Iterable<LongWritable> values, Context context) throws IOException, InterruptedException {
        long count = 0;
        for (LongWritable value : values) {
            count += value.get();
        }
        context.write(key, new LongWritable(count));
    }
}

package com.item.test;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

public class Action {
    public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf);
        job.setJarByClass(Action.class);
        job.setMapperClass(MapAction.class);
        job.setReducerClass(ReduceAction.class);

        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(LongWritable.class);

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(LongWritable.class);

        FileInputFormat.setInputPaths(job,new Path("/info/info.txt"));
        FileOutputFormat.setOutputPath(job,new Path("/infos"));

        boolean b = job.waitForCompletion(true);
        System.exit(b?0:1);
    }
}

cd /opt/hadoop/share/hadoop/mapreduce
echo "Accept that this is your starting point.Instead of placing judgements on it,see the real,positive value that¡¯s already yours.You cannot change where your past priorities and choices have brought you.Yet you can make use of the wisdom you¡¯ve earned to create a future that fulfils your most treasured dreams.
> ÏàÐŴ˿̾ÍÊÇÄãµÄÆðµã¡£ÎÞÐèÔÙÅжϣ¬¿´µ½ÄãËù¾ß±¸µÄÕæÕýÒâÒåÉϵļÛÖµ¡£Äã¹ýÈ¥ÈÏΪÖØÒªµÄʺÍÒÔÇ°×ö¹ýµÄÑ¡Ôñ¸øÄã´øÀ´ÁËʲô¶¼ÊÇÎÞ·¨¸Ä±ä µÄ¡£È»¶øÄã¿ÉÒÔ³ä·ÖÀûÓÃÄãµÄÖÇ»ÛÈ¥´´ÔìδÀ´£¬ÊµÏÖÄã×îÕä°®µÄÃÎÏë¡£" >info.txt
hadoop fs -mkdir /info
hadoop fs -put info.txt /info/info.txt
hadoop fs -cat /info/info.txt

hadoop jar demo.jar com/item/test/Action /info/info.txt /infos
hadoop fs -cat /infos/part-r-00000