Hadoop学习笔记－入门伪分布式配置（Mac OS,0.21.0,Eclipse 3.6）

平惠9668

说实话，Hadoop的入门学习配置比我想像中的要简单，当然，Hadoop本身是比较复杂的（那么厚厚的一本书就能说明问题）。
开发环境：Mac OS（Unix）
Hadoop版本：0.21.0
Eclipse版本: 3.6.0
第一步：下载Hadoop
下载地址：http://hadoop.apache.org/common/releases.html#Download
注意，当前21版本的Hadoop是不稳定、不支持并且不保证安全的最新版本。
第二步：配置Hadoop
将下载的Hadoop压缩文件解压缩，找到conf目录，打开core-site.xml，修改代码如下所示：

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<!-- Put site-specific property overrides in this file. -->
<configuration>
<property>
<name>fs.default.name</name>
<value>localhost:9000</value>
</property>
</configuration>


找到mapred-site.xml修改代码如下所示：

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<!-- Put site-specific property overrides in this file. -->
<configuration>
<property>
<name>mapred.job.tracker</name>
<value>localhost:9001</value>
</property>
</configuration>


找到hdfs-site.xml修改代码如下所示：

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<!-- Put site-specific property overrides in this file. -->
<configuration>
<property>
<name>dfs.replication</name>
<value>1</value>
</property>
</configuration>


找到hadoop-env.sh打开，加入以下配置
引用

export JAVA_HOME=/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home
export HADOOP_INSTALL=/Users/alex/Documents/DevRes/hadoop-0.21.0
export PATH=$PATH:$HADOOP_INSTALL/bin


其中，具体的目录根据你的实际情况配置。

第二步：配置SSH
windows版本可安装openssh，本章主要介绍Mac OS，打开“系统偏好设置”，找到共享，勾选远程登录，如下图所示：

第三步：运行Hadoop
打开终端，定位到Hadoop目录输入以下命令：
bin/hadoop namenode -format
此时终端输出：
引用

DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.
11/09/04 21:19:38 INFO namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG:   host = localhost/127.0.0.1
STARTUP_MSG:   args = [-format]
STARTUP_MSG:   version = 0.21.0
STARTUP_MSG:   classpath = /Users/alex/documents/devres/hadoop-0.21.0/bin/../conf:/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home/lib/tools.jar:/Users/alex/documents/devres/hadoop-0.21.0/bin/..:/Users/alex/documents/devres/hadoop-0.21.0/bin/../hadoop-common-0.21.0.ja

.........省略若干

STARTUP_MSG:   build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.21 -r 985326; compiled by 'tomwhite' on Tue Aug 17 01:02:28 EDT 2010
************************************************************/
11/09/04 21:19:39 INFO namenode.FSNamesystem: defaultReplication = 1
11/09/04 21:19:39 INFO namenode.FSNamesystem: maxReplication = 512
11/09/04 21:19:39 INFO namenode.FSNamesystem: minReplication = 1
11/09/04 21:19:39 INFO namenode.FSNamesystem: maxReplicationStreams = 2
11/09/04 21:19:39 INFO namenode.FSNamesystem: shouldCheckForEnoughRacks = false
11/09/04 21:19:39 INFO security.Groups: Group mapping impl=org.apache.hadoop.security.ShellBasedUnixGroupsMapping; cacheTimeout=300000
11/09/04 21:19:39 INFO namenode.FSNamesystem: fsOwner=alex
11/09/04 21:19:39 INFO namenode.FSNamesystem: supergroup=supergroup
11/09/04 21:19:39 INFO namenode.FSNamesystem: isPermissionEnabled=true
11/09/04 21:19:39 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
11/09/04 21:19:39 INFO common.Storage: Image file of size 110 saved in 0 seconds.
11/09/04 21:19:39 INFO common.Storage: Storage directory /tmp/hadoop-alex/dfs/name has been successfully formatted.
11/09/04 21:19:39 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at localhost/127.0.0.1
************************************************************/


然后输入bin/start-all.sh
在启动期间会多次要求输入密码（你机器的登录密码）
此时终端输出：
引用

This script is Deprecated. Instead use start-dfs.sh and start-mapred.sh
starting namenode, logging to /Users/alex/documents/devres/hadoop-0.21.0/bin/../logs/hadoop-alex-namenode-localhost.out
Password:
localhost: starting datanode, logging to /Users/alex/documents/devres/hadoop-0.21.0/bin/../logs/hadoop-alex-datanode-localhost.out
Password:
localhost: starting secondarynamenode, logging to /Users/alex/documents/devres/hadoop-0.21.0/bin/../logs/hadoop-alex-secondarynamenode-localhost.out
starting jobtracker, logging to /Users/alex/documents/devres/hadoop-0.21.0/bin/../logs/hadoop-alex-jobtracker-localhost.out
Password:
localhost: starting tasktracker, logging to /Users/alex/documents/devres/hadoop-0.21.0/bin/../logs/hadoop-alex-tasktracker-localhost.out


第四步：检查启动
打开连接地址http://localhost:50070
如果找不到页面，请查看log日志（在hadoop目录中的log文件夹下），否则应当会看到以下页面：

然后再打开地址http://localhost:50030/
应当能看到以下页面（如果看不到，则证明你的jobtracker启动失败，请查看log）：

至此，Hadoop配置成功。
第五步：测试
将一个文件拷贝到HDFS中，打开终端定位到Hadoop目录，输入以下命令：
bin/hadoop fs -copyFromLocal [源文件] [目标地址]
比如我输入的是：
bin/hadoop fs -copyFromLocal /Users/alex/desktop/persons.rtf hdfs://localhost/tmp/hadoop-alex
此时终端会输出以下文字：
引用

11/09/04 21:23:45 INFO security.Groups: Group mapping impl=org.apache.hadoop.security.ShellBasedUnixGroupsMapping; cacheTimeout=300000
11/09/04 21:23:45 WARN conf.Configuration: mapred.task.id is deprecated. Instead, use mapreduce.task.attempt.id


这样代表成功。

第六步：配置Eclipse
首先找到目录hadoop-0.21.0/mapred/contrib/eclipse-plugin，然后将里面的eclipse-plugin复制到你的Eclipse的plugin文件夹中。
注意，如果该插件无法使用，本文下方有提供。如果还不能使用，请尝试在网络上寻找。
此时打开Eclipse，在Open Perspective中选择其它，找到Map/Reduce视图，打开它。
此时你会发现在Project Explorer和下面的视图中多了一个DFS Locations，右键新建Location如下图所示：

此时会打开一个窗口，对其进行配置，端口号就是我们刚才在core-site.xml中配置的端口好，既9000，如下图所示：

点击确定后即可在左边的Project Explorer面板中对DFS Location进行展开，如下图所示：

第六步：在Eclipse中写代码
在Map/Reduce视图中新建一个Map/Reduce项目（该项目与普通Java项目没什么区别），新建一个Java类，该类主要用于读取我们前面复制到HDFS中的那个文件内容：

package cn.com.fri;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URISyntaxException;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileContext;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.security.AccessControlException;
public class Test {
public static void main(String[] args) throws AccessControlException,
FileNotFoundException, IOException, URISyntaxException {
FileContext fc = FileContext
.getFileContext();//如果运行在hadoop location中，不需要配置URI，否则需要给一个URI
FSDataInputStream fsInput = fc.open(new Path(
"/tmp/hadoop-alex/persons.rtf"));
IOUtils.copyBytes(fsInput, System.out, 4090, false);
fsInput.seek(0);
IOUtils.copyBytes(fsInput, System.out, 4090, false);
}
}

然后右键->Run As->Run on hadoop，此时会让你选择一个location，就选中我们刚才新建的location即可。
因为我用了seek并给了一个位置，所以会打印两遍结果如下：
引用

11/09/04 22:32:33 WARN conf.Configuration: DEPRECATED: hadoop-site.xml found in the classpath. Usage of hadoop-site.xml is deprecated. Instead use core-site.xml, mapred-site.xml and hdfs-site.xml to override properties of core-default.xml, mapred-default.xml and hdfs-default.xml respectively
11/09/04 22:32:33 WARN conf.Configuration: fs.default.name is deprecated. Instead, use fs.defaultFS
11/09/04 22:32:33 INFO security.Groups: Group mapping impl=org.apache.hadoop.security.ShellBasedUnixGroupsMapping; cacheTimeout=300000
11/09/04 22:32:33 WARN conf.Configuration: mapred.task.id is deprecated. Instead, use mapreduce.task.attempt.id
{\rtf1\ansi\ansicpg936\cocoartf1038\cocoasubrtf360
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{\colortbl;\red255\green255\blue255;}
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{\*\listoverridetable{\listoverride\listid1\listoverridecount0\ls1}}
\paperw11900\paperh16840\margl1440\margr1440\vieww11680\viewh11900\viewkind0
\pard\tx220\tx720\tx1133\tx1700\tx2267\tx2834\tx3401\tx3968\tx4535\tx5102\tx5669\tx6236\tx6803\li720\fi-720\ql\qnatural\pardirnatural
\ls1\ilvl0
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{\*\listoverridetable{\listoverride\listid1\listoverridecount0\ls1}}
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\pard\tx220\tx720\tx1133\tx1700\tx2267\tx2834\tx3401\tx3968\tx4535\tx5102\tx5669\tx6236\tx6803\li720\fi-720\ql\qnatural\pardirnatural
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}


rtf中存放的是中文。
＝＝＝＝＝＝＝＝＝＝＝＝＝＝文章结束＝＝＝＝＝＝＝＝＝＝＝＝＝
今天所学习到的地方就到这里。