hodoop中使用MapReduce实例

网址：

1、http://hadoop.apache.org/docs/stable/hadoop-mapreduce-client/hadoop-mapreduce-client-core/MapReduceTutorial.html

2、http://eric-gcm.iteye.com/blog/1807468

3、https://www.cnblogs.com/hehaiyang/p/4484442.html

4、http://hadoop.apache.org/docs/r1.0.4/cn/mapred_tutorial.html  

一、类：WordCount

package com.wave;

import java.io.IOException;
import java.util.StringTokenizer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;


public class WordCount extends Configured implements Tool{

    //map
    public static class StatisMapper extends Mapper<Object, Text, Text, IntWritable>{
        private final static IntWritable one =new IntWritable(1);
        private Text word =new Text();

        @Override
        public void map(Object key, Text value, Context context
        ) throws IOException, InterruptedException {
            StringTokenizer itr =new StringTokenizer(value.toString());
            while (itr.hasMoreTokens()) {
                word.set(itr.nextToken());
                context.write(word, one);
            }
        }
    }

    //reduce
    public static class StatisReducer extends Reducer<Text,IntWritable,Text,IntWritable> {
        private IntWritable result =new IntWritable();

        @Override
        public void reduce(Text key, Iterable<IntWritable> values,Context context
        ) throws IOException, InterruptedException {
            int sum =0;
            for (IntWritable val : values) {
                sum += val.get();
            }
            result.set(sum);
            context.write(key, result);
        }
    }

    //客户端job的配置
    @Override
    public int run(String[] args)throws Exception{
        Configuration conf = new Configuration();


        String[] otherArgs =new GenericOptionsParser(conf, args).getRemainingArgs();
        if (otherArgs.length !=2) {
            System.err.println("Usage: wordcount <in> <out>");
            System.exit(2);
        }

        Job job =new Job(conf, "word count");    //设置一个用户定义的job名称
        job.setJarByClass(WordCount.class);
        job.setMapperClass(StatisMapper.class);    //为job设置Mapper类
        job.setCombinerClass(StatisReducer.class);    //为job设置Combiner类
        job.setReducerClass(StatisReducer.class);    //为job设置Reducer类

        job.setOutputKeyClass(Text.class);        //为job的输出数据设置Key类
        job.setOutputValueClass(IntWritable.class);    //为job输出设置value类
        FileInputFormat.addInputPath(job, new Path(otherArgs[0]));    //为job设置输入路径
        FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));//为job设置输出路径

        //提交作业
        return  job.waitForCompletion(true) ? 0 : 1;
    }


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

        try {
            int result = ToolRunner.run(new WordCount(), args);
            System.exit(result);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

二、intellij IDE 配置设置输入输出目录

Program arguments: input/ output/

三、pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>


    <groupId>com.wave</groupId>
    <artifactId>testMapReduce</artifactId>
    <version>1.0-SNAPSHOT</version>


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


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

        <dependency>
            <groupId>org.apache.hbase</groupId>
            <artifactId>hbase-client</artifactId>
            <version>1.3.1</version>
            <scope>provided</scope>
        </dependency>


        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-mapreduce-client-common</artifactId>
            <version>2.4.1</version>
        </dependency>


        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-mapreduce-client-jobclient</artifactId>
            <version>2.4.1</version>
        </dependency>


        <dependency>
            <groupId>org.apache.hive</groupId>
            <artifactId>hive-cli</artifactId>
            <version>2.1.1</version>
            <scope>provided</scope>
        </dependency>


    </dependencies>>


</project>