Windows/Mac + Maven + Hadoop2.7.3 开发环境配置（含wordcount示例）

    (windows)
    新建系统环境变量 HADOOP_HOME=D:\hadoop\hadoop-2.7.3
    修改path，增加 %HADOOP_HOME%\bin
    
    (mac)
    vim ~/.bash_profile
    export HADOOP_HOME=~/Dev/hadoop/hadoop-2.7.3
    export path=$path:$HADOOP_HOME/bin

    mkdir %HADOOP_HOME%\home
    mkdir %HADOOP_HOME%\home\tmp
    mkdir %HADOOP_HOME%\home\name
    mkdir %HADOOP_HOME%\home\data

    <!-- core-site.xml -->
    <configuration>
        <property>
            <name>hadoop.tmp.dir</name>
            <value>/D:/_Dev/server/hadoop/hadoop-2.7.3/home/tmp</value>
        </property>
        <property>
            <name>dfs.name.dir</name>
            <value>/D:/_Dev/server/hadoop/hadoop-2.7.3/home/name</value>
        </property>
        <property>
            <name>fs.default.name</name>
            <value>hdfs://localhost:9000</value>
        </property>
    </configuration>

    <!-- hdfs-site.xml -->
    <configuration>
        <!-- 这个参数设置为1，因为是单机版hadoop -->
        <property>
            <name>dfs.replication</name>
            <value>1</value>
        </property>
        <property>
            <name>dfs.data.dir</name>
            <value>/D:/_Dev/server/hadoop/hadoop-2.7.3/home/data</value>
        </property>
    </configuration>

    <!--mapred-site.xml -->
    <configuration>
        <property>
           <name>mapreduce.framework.name</name>
           <value>yarn</value>
        </property>
        <property>
           <name>mapred.job.tracker</name>
           <value>hdfs://localhost:9001</value>
        </property>
    </configuration>

    <!-- yarn-site.xml -->
    <configuration>
        <!-- Site specific YARN configuration properties -->
        <property>
           <name>yarn.nodemanager.aux-services</name>
           <value>mapreduce_shuffle</value>
        </property>
        <property>
           <name>yarn.nodemanager.aux-services.mapreduce.shuffle.class</name>
           <value>org.apache.hadoop.mapred.ShuffleHandler</value>
        </property>
    </configuration>

    windows配置,指定 JAVA_HOME 的安装目录，不能有空格。（Program Files 用 PROGRA~1 代替）
    set JAVA_HOME=D:\PROGRA~1\Java\jdk1.8.0

    mac配置
    export HADOOP_HEAPSIZE=2000
    export HADOOP_OPTS="$HADOOP_OPTS -Djava.net.preferIPv4Stack=true -Djava.library.path=$HADOOP_HOME/lib/native"