Hadoop单机版快速搭建及测试

一、快速配置Hadoop并启动(为了快速上手用单机搭建)：

hadoop下载地载:http://mirror.bit.edu.cn/apache/hadoop/ 
1、修改配置文件：
core-site.xml

<configuration>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://localhost:9000</value>
    </property>
</configuration>

hdfs-site.xml

<configuration>
    <property>
        <name>dfs.replication</name>
        <value>1</value>
    </property>
</configuration>

mapred-site.xml

<configuration>
    <property>
        <name>mapreduce.framework.name</name>
        <value>yarn</value>
    </property>
</configuration>

yarn-site.xml

<configuration>
    <property>
        <name>yarn.nodemanager.aux-services</name>
        <value>mapreduce_shuffle</value>
    </property>
</configuration>

hadoop-env.sh

export JAVA_HOME=/usr/java/jdk1.8.0_121

2、格式化文件系统

./hdfs namenode -format

3、启动名称节点和数据节点后台进程

./sbin/start-dfs.sh

 启动ResourceManger和NodeManager后台进程

./sbin/start-yarn.sh

或者只用

./sbin/start-all.sh

二、测试

2.1 HDFS测试

使用浏览器查看hdfs目录，端口号是50070:

操作材料下载

https://pan.baidu.com/s/1hs62YTe

进入hadoop解压目录下的bin目录, HDFS创建目录:

./hdfs dfs -mkdir /wordcount
./hdfs dfs -mkdir /wordcount/result
./hadoop fs -rmr /wordcount/result

拷贝input文件夹到HDFS目录下

./hdfs dfs -put /opt/input /wordcount

查看文件列表：

./hadoop fs -ls /wordcount/input

2.2 MapReduce测试

是参考官方文档的wordcount实验，将wordcount的代码译并打包，放到服务器的目录(/opt/testsource)下（注意不是hdfs的目录下）

并将测试的要进行wordcount的文件放入hdfs的/wordcount/input目录下

执行hadoop job

./hadoop jar /opt/testsource/learning.jar  
          hadoop.WordCount /wordcount/input   /wordcount/result

确认执行结果

hdfs dfs -cat /wordcount/result/*

附wordcount代码：

package hadoop;

/**
 * Created by BD-PC11 on 2017/3/29.
 */

import java.io.IOException;
import java.util.*;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapred.*;
import org.apache.hadoop.util.*;

public class WordCount {

    public static class Map extends MapReduceBase 
                        implements Mapper<LongWritable, Text, Text, IntWritable> {
        private final static IntWritable one = new IntWritable(1);
        private Text word = new Text();

        public void map(LongWritable key, Text value, OutputCollector<Text, IntWritable> output, 
                        Reporter reporter) throws IOException {
            String line = value.toString();
            StringTokenizer tokenizer = new StringTokenizer(line);
            while (tokenizer.hasMoreTokens()) {
                word.set(tokenizer.nextToken());
                output.collect(word, one);
            }
        }
    }

    public static class Reduce extends MapReduceBase 
                        implements Reducer<Text, IntWritable, Text, IntWritable> {
        public void reduce(Text key, Iterator<IntWritable> values, 
                           OutputCollector<Text, IntWritable> output, 
                           Reporter reporter) throws IOException {
            int sum = 0;
            while (values.hasNext()) {
                sum += values.next().get();
            }
            output.collect(key, new IntWritable(sum));
        }
    }

    public static void main(String[] args) throws Exception {
        JobConf conf = new JobConf(WordCount.class);
        conf.setJobName("wordcount");

        conf.setOutputKeyClass(Text.class);
        conf.setOutputValueClass(IntWritable.class);

        conf.setMapperClass(Map.class);
        conf.setCombinerClass(Reduce.class);
        conf.setReducerClass(Reduce.class);

        conf.setInputFormat(TextInputFormat.class);
        conf.setOutputFormat(TextOutputFormat.class);

        FileInputFormat.setInputPaths(conf, new Path(args[0]));
        FileOutputFormat.setOutputPath(conf, new Path(args[1]));

        JobClient.runJob(conf);
    }
}