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跟我一起hadoop（1）-hadoop2.6安装与使用

伪分布式

hadoop的三种安装方式：

Local (Standalone) Mode
Pseudo-Distributed Mode
Fully-Distributed Mode

安装之前需要

$ sudo apt-get install ssh$ sudo apt-get install rsync

详见： http://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-common/SingleCluster.html

伪分布式配置

Configuration

修改下边:

etc/hadoop/core-site.xml:

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

etc/hadoop/hdfs-site.xml:

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

配置ssh

$ ssh-keygen -t dsa -P '' -f ~/.ssh/id_dsa   $ cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys

如果想运行在yarn上

需要执行下边的步骤：

Configure parameters as follows:

etc/hadoop/mapred-site.xml:

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

etc/hadoop/yarn-site.xml:

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

Start ResourceManager daemon and NodeManager daemon:
```
$ sbin/start-yarn.sh
```
Browse the web interface for the ResourceManager; by default it is available at:
- ResourceManager - http://localhost:8088/
Run a MapReduce job.
When you're done, stop the daemons with:
```
$ sbin/stop-yarn.sh
```

输入：

http://localhost:8088/

可以看到

跟我一起hadoop（1）-hadoop2.6安装与使用

启动yarn后

Format the filesystem:
```
$ bin/hdfs namenode -format
```
Start NameNode daemon and DataNode daemon:
```
$ sbin/start-dfs.sh
```
The hadoop daemon log output is written to the $HADOOP_LOG_DIR directory (defaults to $HADOOP_HOME/logs ).
Browse the web interface for the NameNode; by default it is available at:
- NameNode - http://localhost:50070/

输入后得到：

跟我一起hadoop（1）-hadoop2.6安装与使用

然后执行测试

Make the HDFS directories required to execute MapReduce jobs:

$ bin/hdfs dfs -mkdir /user   $ bin/hdfs dfs -mkdir /user/<username>

Copy the input files into the distributed filesystem:
```
$ bin/hdfs dfs -put etc/hadoop input
```

Run some of the examples provided:

$ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.6.0.jar grep input output 'dfs[a-z.]+'

Examine the output files:

Copy the output files from the distributed filesystem to the local filesystem and examine them:
```
$ bin/hdfs dfs -get output output   $ cat output/*
```
or

View the output files on the distributed filesystem:
```
$ bin/hdfs dfs -cat output/*
```

看运行的情况：

跟我一起hadoop（1）-hadoop2.6安装与使用

查看结果

跟我一起hadoop（1）-hadoop2.6安装与使用

测试执行成功，可以编写本地代码了。

eclipse hadoop2.6插件使用

下载源码：

git clone https://github.com/winghc/hadoop2x-eclipse-plugin.git

下载过程：

跟我一起hadoop（1）-hadoop2.6安装与使用

编译插件：

cd src/contrib/eclipse-plugin

ant jar -Dversion=2.6.0 -Declipse.home=/usr/local/eclipse -Dhadoop.home=/usr/local/hadoop-2.6.0 //路径根据自己的配置跟我一起hadoop（1）-hadoop2.6安装与使用

复制编译好的jar到eclipse插件目录，重启eclipse

window ->preference -> hadoop Map/Reduce -> Hadoop installation directory

配置Map/Reduce 视图

window ->Open Perspective -> other->Map/Reduce -> 点击“OK”

windows → show view → other->Map/Reduce Locations-> 点击“OK”

控制台会多出一个“Map/Reduce Locations”的Tab页

在“Map/Reduce Locations” Tab页点击图标<大象+>或者在空白的地方右键，选择“New Hadoop location…”，弹出对话框“New hadoop location…”，配置如下内容：将ha1改为自己的hadoop用户

跟我一起hadoop（1）-hadoop2.6安装与使用

注意：MR Master和DFS Master配置必须和mapred-site.xml和core-site.xml等配置文件一致。

打开Project Explorer,查看HDFS文件系统。

新建Map/Reduce任务

File->New->project->Map/Reduce Project->Next

编写WordCount类：记得先把服务都起来

/**  *   */ package com.zongtui;  /**  * ClassName: WordCount <br/>  * Function: TODO ADD FUNCTION. <br/>  * date: Jun 28, 2015 5:34:18 AM <br/>  *  * @author zhangfeng  * @version   * @since JDK 1.7  */  import java.io.IOException; import java.util.Iterator; import java.util.StringTokenizer;  import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapred.FileInputFormat; import org.apache.hadoop.mapred.FileOutputFormat; import org.apache.hadoop.mapred.JobClient; import org.apache.hadoop.mapred.JobConf; import org.apache.hadoop.mapred.MapReduceBase; import org.apache.hadoop.mapred.Mapper; import org.apache.hadoop.mapred.OutputCollector; import org.apache.hadoop.mapred.Reducer; import org.apache.hadoop.mapred.Reporter; import org.apache.hadoop.mapred.TextInputFormat; import org.apache.hadoop.mapred.TextOutputFormat;  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.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);     } }

user/admin123/input/hadoop是你上传在hdfs的文件夹（自己创建），里面放要处理的文件。ouput1放输出结果

跟我一起hadoop（1）-hadoop2.6安装与使用

将程序放在hadoop集群上运行：右键-->Runas -->Run on Hadoop,最终的输出结果会在HDFS相应的文件夹下显示。至此，ubuntu下hadoop-2.6.0 eclipse插件配置完成。

遇到异常

Exception in thread "main" org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory hdfs://localhost:9000/output already exists     at org.apache.hadoop.mapred.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:132)     at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:564)     at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:432)     at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1296)     at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1293)     at java.security.AccessController.doPrivileged(Native Method)     at javax.security.auth.Subject.doAs(Subject.java:415)     at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)     at org.apache.hadoop.mapreduce.Job.submit(Job.java:1293)     at org.apache.hadoop.mapred.JobClient$1.run(JobClient.java:562)     at org.apache.hadoop.mapred.JobClient$1.run(JobClient.java:557)     at java.security.AccessController.doPrivileged(Native Method)     at javax.security.auth.Subject.doAs(Subject.java:415)     at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)     at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:557)     at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:548)     at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:833)     at com.zongtui.WordCount.main(WordCount.java:83)