Hadoop Windows IDEA

java jdk1.8都可以了

注意jdk的路径要拷贝到一个没有空格的路径改掉JAVA_HOME系统环境变量

在etc/hadoop/hadoop_env.cmd里有设置%JAVA_HOME%了不用管，但是不支持带空格的路径，hadoop路径也不能有空格

首先：

配置输入和输出结果文件夹

1. 添加和src目录同级的input文件夹到项目中

在input文件夹中放置一个或多个输入文件源

新建一个test.segmented文件

内容如下:

dfdfadgdgag
aadads
fudflcl
cckcer
fadf
dfdfadgdgag
fudflcl
fuck
fuck
fuckfuck
haha
aaa

1. 配置运行参数
   
   在Intellij菜单栏中选择Run->Edit Configurations，在弹出来的对话框中点击+，新建一个Application配置。配置Main class为WordCount（可以点击右边的...选择），
   
   Program arguments为input/ output/，即输入路径为刚才创建的input文件夹，输出为output
   
   另外我建议改下IDEA maven的镜像不然会很慢
   
   修改方法：在~/.m2目录下的settings.xml文件中，（如果该文件不存在，则需要从maven/conf目录下拷贝一份），找到标签，添加如下子标签：
   
   然后去对照一下IDEA里的maven目录与settings.xml文件目录

<mirror>
    <id>alimaven</id>
    <name>aliyun maven</name>
    <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
    <mirrorOf>central</mirrorOf>
</mirror>

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>dsf</groupId>
    <artifactId>dsff</artifactId>
    <version>1.0-SNAPSHOT</version>
    <repositories>
        <repository>
            <id>apache</id>
            <url>http://maven.apache.org</url>
        </repository>
    </repositories>

    <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.hadoop</groupId>
            <artifactId>hadoop-yarn-common</artifactId>
            <version>2.7.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-mapreduce-client-common</artifactId>
            <version>2.7.3</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-dependency-plugin</artifactId>
                <configuration>
                    <excludeTransitive>false</excludeTransitive>
                    <stripVersion>true</stripVersion>
                    <outputDirectory>./lib</outputDirectory>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

1. 新建一个WordCount.java文件
   
   内容如下：

import java.io.IOException;
import java.util.StringTokenizer;

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;

public class WordCount {

    public static class TokenizerMapper
            extends Mapper<Object, Text, Text, IntWritable> {

        private final static IntWritable one = new IntWritable(1);
        private Text word = new Text();

        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);
            }
        }
    }

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

        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);
        }
    }

    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf, "word count");
        job.setJarByClass(WordCount.class);
        job.setMapperClass(TokenizerMapper.class);
        job.setCombinerClass(IntSumReducer.class);
        job.setReducerClass(IntSumReducer.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}

1. 然后要用windows可以看下教程：
   
   这一定是可以的也是最方便的了
   
   https://www.cs.helsinki.fi/u/jilu/paper/hadoop_on_win.pdf
   
   首先下载hadoop二进制程序
   
   2.7.3 source：
   
   http://hadoop.apache.org/releases.html
   
   替换掉hadoop-2.7.3里的bin文件
   
   替换程序：
   
   https://github.com/srccodes/hadoop-common-2.2.0-bin/archive/master.zip
   
   设置环境：
   
   这里注意下最好是在IDEA里设置HADOOP_HOME环境变量,如果设置的是系统环境变量那么你就还需要修改，我都设置了。。。
   
   hadoop-2.7.3-src\hadoop-common-project\hadoop-common\src\main\java\org\apache\hadoop\util\Shell.java
   
   源码：
   
   2.7.3 source：
   
   http://hadoop.apache.org/releases.html

private static String checkHadoopHome() {

    // first check the Dflag hadoop.home.dir with JVM scope
		//System.setProperty("hadoop.home.dir", "...");
    String home = System.getProperty("hadoop.home.dir");

    // fall back to the system/user-global env variable
    if (home == null) {
      home = System.getenv("HADOOP_HOME");
    }

    try {
       // couldn't find either setting for hadoop's home directory
       if (home == null) {
         throw new IOException("HADOOP_HOME or hadoop.home.dir are not set.");
       }

       if (home.startsWith("\"") && home.endsWith("\"")) {
         home = home.substring(1, home.length()-1);
       }

       // check that the home setting is actually a directory that exists
       File homedir = new File(home);
       if (!homedir.isAbsolute() || !homedir.exists() || !homedir.isDirectory()) {
         throw new IOException("Hadoop home directory " + homedir
           + " does not exist, is not a directory, or is not an absolute path.");
       }

       home = homedir.getCanonicalPath();

    } catch (IOException ioe) {
      if (LOG.isDebugEnabled()) {
        LOG.debug("Failed to detect a valid hadoop home directory", ioe);
      }
      home = null;
    }
    //固定本机的hadoop地址
    home="D:\\hadoop-2.7.3";
    return home;
  }

home = System.getenv("HADOOP_HOME");

如果是设置系统环境变量，这里获取的HADOOP_HOME的home目录的字符串会在字符串开始加入一个'\u202A'字符，(好像是)代表c/c++/java源码(神奇)

然后把文件拷贝到你的工程下，idea会优先查找工程目录下的(可以先拷过来再改)

如果是设置IDEA里的环境变量就不用改Shell.java了

之后按照文档里的改下NativeIO.java文件

hadoop-2.7.3-src\hadoop-common-project\hadoop-common\src\main\java\org\apache\hadoop\io\nativeio\NativeIO.java

修改行609左右

    return access0(path, desiredAccess.accessRight());

改成

    return true;

也拷到工程下来就行了

另外建议以管理员模式打开IDEA

由于Hadoop的设定，下次运行时务必删除output文件夹！

好了,运行程序,结果如下:

aaa 1

aadads 1

cckcer 1

dfdfadgdgag 2

fadf 1

fuck 2

fuckfuck 1

fudflcl 2

haha 1