1、创建一个maven工程

2、POM文件

<?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.sogou</groupId>
    <artifactId>teemo-dc-etl</artifactId>
    <version>1.0.0</version>
    <packaging>jar</packaging>

    <name>teemo-dc-etl</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <mahout.version>0.5</mahout.version>
        <mahout.groupid>org.apache.mahout</mahout.groupid>
        <spring.version>3.0.6.RELEASE</spring.version>
    </properties>

    <repositories>
    <repository>
        <id>maven-ali</id>
        <url>http://maven.twttr.com/</url>
        <releases>
            <enabled>true</enabled>
        </releases>
        <snapshots>
            <enabled>true</enabled>
            <updatePolicy>always</updatePolicy>
            <checksumPolicy>fail</checksumPolicy>
        </snapshots>
    </repository>
    </repositories>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-hdfs</artifactId>
            <version>2.5.0</version>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>2.5.1</version>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-common</artifactId>
            <version>2.5.0</version>
        </dependency>

        <dependency>
            <groupId>com.hadoop.gplcompression</groupId>
            <artifactId>hadoop-lzo</artifactId>
            <version>0.4.19</version>
        </dependency>

        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-yarn-common</artifactId>
            <version>2.5.2</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.4</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <!--
            bind the maven-assembly-plugin to the package phase
            this will create a jar file without the storm dependencies
            suitable for deployment to a cluster.
             -->
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass></mainClass>
                        </manifest>
                    </archive>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase> <!-- packaging phase -->
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.14.1</version>
                <configuration>
                    <argLine>-Xmx2048m</argLine>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>
这里有个lzo包，需要增加twiter的资源库
3、mapreduce文件写法

package com.sogou.teemo.test;

import org.apache.hadoop.conf.Configuration;
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 java.io.IOException;
import java.util.StringTokenizer;

public class WordCount {
    /* Mapper */
    public static class TokenizerMapper 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);
            }
        }
    }

    /* Reducer */
    public static class IntSumReducer 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);
        }
    }

    /* 启动 MapReduce Job */
    public static void main(String[] args) throws Exception{
        System.setProperty("hadoop.home.dir","D:/hadoop-2.6.5" );
        Configuration conf = new Configuration();
        /*if(args.length != 2){
            System.err.println("Usage: wordcount <int> <out>");
            System.exit(2);
        }*/
        String arg1 = "input";
        String arg2 = "output";
        Job job = new Job(conf, "word count");
        job.setJarByClass(WordCount.class);
        job.setMapperClass(TokenizerMapper.class);
        job.setReducerClass(IntSumReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        FileInputFormat.addInputPath(job,new Path(arg1));
        FileOutputFormat.setOutputPath(job,new Path(arg2));
        System.exit(job.waitForCompletion(true)?0:1);
    }
}