1.下載hadoo安裝到windows本地 

    地址 https://archive.apache.org/dist/hadoop/core/hadoop-2.6.0/hadoop-2.6.0.tar.gz

2. 解壓之後進行設定環境變數

     新建  HADOOP_HOME     D:\software\hadoop-2.6.0

     Path中增加   %HADOOP_HOME%\bin 和   %HADOOP_HOME%\sbin

3.範例程式碼

專案結構

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.xiaobao</groupId>
	<artifactId>hadooptest</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>


	<dependencies>
		<dependency>
			<groupId>org.apache.hadoop</groupId>
			<artifactId>hadoop-client</artifactId>
			<version>2.6.0</version>
		</dependency>
	</dependencies>


</project>
 

log4j.properties

log4j.rootLogger = debug,stdout

log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n
 

 WordCountMapper.java

package com.xiaobao.wordcount;

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

import java.io.IOException;

public class WordCountMapper extends Mapper<LongWritable, Text, Text, IntWritable> {

    @Override
    protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

        String[] words = value.toString().split("\\s+");

        for (String word : words) {
            context.write(new Text(word), new IntWritable(1));
        }
    }
}

WordCountReducer.java

package com.xiaobao.wordcount;

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

import java.io.IOException;

public class WordCountReducer extends Reducer<Text, IntWritable, Text, IntWritable> {

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

RunJob.java

package com.xiaobao.wordcount;


import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
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.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

public class RunJob {

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

        Configuration configuration = new Configuration();

        FileSystem fs = FileSystem.get(configuration);

        Job job = Job.getInstance(configuration);
        job.setJarByClass(RunJob.class);
        job.setJobName("wordCount");

        job.setMapperClass(WordCountMapper.class);
        job.setReducerClass(WordCountReducer.class);

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

        FileInputFormat.addInputPath(job, new Path("/wordcount/input"));
        Path outPath = new Path("/wordcount/output");
        if (fs.exists(outPath)) {
            fs.delete(outPath, true);
        }
        FileOutputFormat.setOutputPath(job, outPath);

        boolean completion = job.waitForCompletion(true);
        if (completion) {
            System.out.println("執行完成");
        }


    }
}

4. 然後在專案的根目錄下建立    D:\wordcount\input  和  D:\wordcount\output資料夾input 資料夾中放入 words.txt內容為

hello world
hello hadoop
hadoop yes
hadoop no

5. 然後啟動RunJob的main方法，會出現報錯

[ERROR] 2018-11-13 10:12:43,981 method:org.apache.hadoop.util.Shell.getWinUtilsPath(Shell.java:373)
Failed to locate the winutils binary in the hadoop binary path
java.io.IOException: Could not locate executable null\bin\winutils.exe in the Hadoop binaries.
	at org.apache.hadoop.util.Shell.getQualifiedBinPath(Shell.java:355)
	at org.apache.hadoop.util.Shell.getWinUtilsPath(Shell.java:370)
	at org.apache.hadoop.util.Shell.<clinit>(Shell.java:363)
	at org.apache.hadoop.util.StringUtils.<clinit>(StringUtils.java:79)
	at org.apache.hadoop.security.Groups.parseStaticMapping(Groups.java:104)
	at org.apache.hadoop.security.Groups.<init>(Groups.java:86)
	at org.apache.hadoop.security.Groups.<init>(Groups.java:66)
	at org.apache.hadoop.security.Groups.getUserToGroupsMappingService(Groups.java:280)
	at org.apache.hadoop.security.UserGroupInformation.initialize(UserGroupInformation.java:271)
	at org.apache.hadoop.security.UserGroupInformation.ensureInitialized(UserGroupInformation.java:248)
	at org.apache.hadoop.security.UserGroupInformation.loginUserFromSubject(UserGroupInformation.java:763)
	at org.apache.hadoop.security.UserGroupInformation.getLoginUser(UserGroupInformation.java:748)
	at org.apache.hadoop.security.UserGroupInformation.getCurrentUser(UserGroupInformation.java:621)
	at org.apache.hadoop.fs.FileSystem$Cache$Key.<init>(FileSystem.java:2753)
	at org.apache.hadoop.fs.FileSystem$Cache$Key.<init>(FileSystem.java:2745)
	at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2611)
	at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:370)
	at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:169)
	at com.xiaobao.wordcount.RunJob.main(RunJob.java:24)

5.看日誌的錯誤資訊是沒有winutils.exe這個檔案，需要下載winutils.exe檔案，注意要和自己hadoop版本一致，否則還是報錯

     下載地址: https://github.com/steveloughran/winutils 從github下載下來壓縮包，將對應版本的bin下的檔案拷貝並替換自己本         地的hadoop的bin目錄中檔案

6. 繼續執行main方法，執行成功

    此時  D:\wordcount\output 資料夾中出現執行完成的檔案_SUCCESS  和 part-r-00000 等檔案， _SUCCESS  代表執行成功，  part-r-00000中存單詞統計的結果

hadoop	3
hello	2
no	1
world	1
yes	1