Hadoop學習初步：Maven構建Hadoop項目

原創 ACMiao_ 2018-09-04 12:10

轉自：http://blog.fens.me/hadoop-maven-eclipse/


hadoop-maven

前言

Hadoop的MapReduce環境是一個複雜的編程環境，所以我們要儘可能地簡化構建MapReduce項目的過程。Maven是一個很不錯的自動化項目構建工具，通過Maven來幫助我們從複雜的環境配置中解脫出來，從而標準化開發過程。所以，寫MapReduce之前，讓我們先花點時間把刀磨快！！當然，除了Maven還有其他的選擇Gradle(推薦), Ivy….

後面將會有介紹幾篇MapReduce開發的文章，都要依賴於本文中Maven的構建的MapReduce環境。

目錄

  1. Maven介紹
  2. Maven安裝(win)
  3. Hadoop開發環境介紹
  4. 用Maven構建Hadoop環境
  5. MapReduce程序開發
  6. 模板項目上傳github

1. Maven介紹

Apache Maven，是一個Java的項目管理及自動構建工具，由Apache軟件基金會所提供。基於項目對象模型（縮寫：POM）概念，Maven利用一箇中央信息片斷能管理一個項目的構建、報告和文檔等步驟。曾是Jakarta項目的子項目，現爲獨立Apache項目。

maven的開發者在他們開發網站上指出，maven的目標是要使得項目的構建更加容易，它把編譯、打包、測試、發佈等開發過程中的不同環節有機的串聯了起來，併產生一致的、高質量的項目信息，使得項目成員能夠及時地得到反饋。maven有效地支持了測試優先、持續集成，體現了鼓勵溝通，及時反饋的軟件開發理念。如果說Ant的複用是建立在”拷貝–粘貼”的基礎上的，那麼Maven通過插件的機制實現了項目構建邏輯的真正複用。

2. Maven安裝(win)

下載Maven：http://maven.apache.org/download.cgi

下載最新的xxx-bin.zip文件，在win上解壓到 D:\toolkit\maven3

並把maven/bin目錄設置在環境變量PATH：

win7-maven

然後，打開命令行輸入mvn，我們會看到mvn命令的運行效果


~ C:\Users\Administrator>mvn
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.086s
[INFO] Finished at: Mon Sep 30 18:26:58 CST 2013
[INFO] Final Memory: 2M/179M
[INFO] ------------------------------------------------------------------------
[ERROR] No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format : or :[:]:. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-class
es, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy. -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/NoGoalSpecifiedException

安裝Eclipse的Maven插件：Maven Integration for Eclipse

Maven的Eclipse插件配置

eclipse-maven

3. Hadoop開發環境介紹

hadoop-dev

如上圖所示，我們可以選擇在win中開發，也可以在linux中開發，本地啓動Hadoop或者遠程調用Hadoop，標配的工具都是Maven和Eclipse。

Hadoop集羣系統環境：

  • Linux: Ubuntu 12.04.2 LTS 64bit Server
  • Java: 1.6.0_29
  • Hadoop: hadoop-1.0.3，單節點，IP:192.168.1.210

4. 用Maven構建Hadoop環境

  • 1. 用Maven創建一個標準化的Java項目
  • 2. 導入項目到eclipse
  • 3. 增加hadoop依賴，修改pom.xml
  • 4. 下載依賴
  • 5. 從Hadoop集羣環境下載hadoop配置文件
  • 6. 配置本地host

1). 用Maven創建一個標準化的Java項目


~ D:\workspace\java>mvn archetype:generate -DarchetypeGroupId=org.apache.maven.archetypes -DgroupId=org.conan.myhadoop.mr
-DartifactId=myHadoop -DpackageName=org.conan.myhadoop.mr -Dversion=1.0-SNAPSHOT -DinteractiveMode=false
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] >>> maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom >>>
[INFO]
[INFO] <<< maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom <<<
[INFO]
[INFO] --- maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom ---
[INFO] Generating project in Batch mode
[INFO] No archetype defined. Using maven-archetype-quickstart (org.apache.maven.archetypes:maven-archetype-quickstart:1.
0)
Downloading: http://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archet
ype-quickstart-1.0.jar
Downloaded: http://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archety
pe-quickstart-1.0.jar (5 KB at 4.3 KB/sec)
Downloading: http://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archet
ype-quickstart-1.0.pom
Downloaded: http://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archety
pe-quickstart-1.0.pom (703 B at 1.6 KB/sec)
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Old (1.x) Archetype: maven-archetype-quickstart:1.0
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: groupId, Value: org.conan.myhadoop.mr
[INFO] Parameter: packageName, Value: org.conan.myhadoop.mr
[INFO] Parameter: package, Value: org.conan.myhadoop.mr
[INFO] Parameter: artifactId, Value: myHadoop
[INFO] Parameter: basedir, Value: D:\workspace\java
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] project created from Old (1.x) Archetype in dir: D:\workspace\java\myHadoop
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 8.896s
[INFO] Finished at: Sun Sep 29 20:57:07 CST 2013
[INFO] Final Memory: 9M/179M
[INFO] ------------------------------------------------------------------------

進入項目，執行mvn命令


~ D:\workspace\java>cd myHadoop
~ D:\workspace\java\myHadoop>mvn clean install
[INFO]
[INFO] --- maven-jar-plugin:2.3.2:jar (default-jar) @ myHadoop ---
[INFO] Building jar: D:\workspace\java\myHadoop\target\myHadoop-1.0-SNAPSHOT.jar
[INFO]
[INFO] --- maven-install-plugin:2.3.1:install (default-install) @ myHadoop ---
[INFO] Installing D:\workspace\java\myHadoop\target\myHadoop-1.0-SNAPSHOT.jar to C:\Users\Administrator\.m2\repository\o
rg\conan\myhadoop\mr\myHadoop\1.0-SNAPSHOT\myHadoop-1.0-SNAPSHOT.jar
[INFO] Installing D:\workspace\java\myHadoop\pom.xml to C:\Users\Administrator\.m2\repository\org\conan\myhadoop\mr\myHa
doop\1.0-SNAPSHOT\myHadoop-1.0-SNAPSHOT.pom
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4.348s
[INFO] Finished at: Sun Sep 29 20:58:43 CST 2013
[INFO] Final Memory: 11M/179M
[INFO] ------------------------------------------------------------------------

2). 導入項目到eclipse

我們創建好了一個基本的maven項目，然後導入到eclipse中。 這裏我們最好已安裝好了Maven的插件。

hadoop-eclipse

3). 增加hadoop依賴

這裏我使用hadoop-1.0.3版本，修改文件：pom.xml


~ vi pom.xml

<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.conan.myhadoop.mr</groupId>
<artifactId>myHadoop</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>myHadoop</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-core</artifactId>
<version>1.0.3</version>
</dependency>

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.4</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>

4). 下載依賴

下載依賴：

~ mvn clean install

在eclipse中刷新項目：

hadoop-eclipse-maven

項目的依賴程序，被自動加載的庫路徑下面。

5). 從Hadoop集羣環境下載hadoop配置文件

  • core-site.xml
  • hdfs-site.xml
  • mapred-site.xml

查看core-site.xml


<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
<property>
<name>fs.default.name</name>
<value>hdfs://master:9000</value>
</property>
<property>
<name>hadoop.tmp.dir</name>
<value>/home/conan/hadoop/tmp</value>
</property>
<property>
<name>io.sort.mb</name>
<value>256</value>
</property>
</configuration>

查看hdfs-site.xml


<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
<property>
<name>dfs.data.dir</name>
<value>/home/conan/hadoop/data</value>
</property>
<property>
<name>dfs.replication</name>
<value>1</value>
</property>
<property>
<name>dfs.permissions</name>
<value>false</value>
</property>
</configuration>

查看mapred-site.xml


<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
<property>
<name>mapred.job.tracker</name>
<value>hdfs://master:9001</value>
</property>
</configuration>

保存在src/main/resources/hadoop目錄下面

hadoop-config

刪除原自動生成的文件：App.java和AppTest.java

6).配置本地host，增加master的域名指向


~ vi c:/Windows/System32/drivers/etc/hosts

192.168.1.210 master

6. MapReduce程序開發

編寫一個簡單的MapReduce程序，實現wordcount功能。

新一個Java文件：WordCount.java


package org.conan.myhadoop.mr;

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.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 WordCountMapper extends MapReduceBase implements Mapper<Object, Text, Text, IntWritable> {
        private final static IntWritable one = new IntWritable(1);
        private Text word = new Text();

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

        }
    }

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

        @Override
        public void reduce(Text key, Iterator values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
            int sum = 0;
            while (values.hasNext()) {
                sum += values.next().get();
            }
            result.set(sum);
            output.collect(key, result);
        }
    }

    public static void main(String[] args) throws Exception {
        String input = "hdfs://192.168.1.210:9000/user/hdfs/o_t_account";
        String output = "hdfs://192.168.1.210:9000/user/hdfs/o_t_account/result";

        JobConf conf = new JobConf(WordCount.class);
        conf.setJobName("WordCount");
        conf.addResource("classpath:/hadoop/core-site.xml");
        conf.addResource("classpath:/hadoop/hdfs-site.xml");
        conf.addResource("classpath:/hadoop/mapred-site.xml");

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

        conf.setMapperClass(WordCountMapper.class);
        conf.setCombinerClass(WordCountReducer.class);
        conf.setReducerClass(WordCountReducer.class);

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

        FileInputFormat.setInputPaths(conf, new Path(input));
        FileOutputFormat.setOutputPath(conf, new Path(output));

        JobClient.runJob(conf);
        System.exit(0);
    }

}

啓動Java APP.

控制檯錯誤


2013-9-30 19:25:02 org.apache.hadoop.util.NativeCodeLoader 
警告: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2013-9-30 19:25:02 org.apache.hadoop.security.UserGroupInformation doAs
嚴重: PriviledgedActionException as:Administrator cause:java.io.IOException: Failed to set permissions of path: \tmp\hadoop-Administrator\mapred\staging\Administrator1702422322\.staging to 0700
Exception in thread "main" java.io.IOException: Failed to set permissions of path: \tmp\hadoop-Administrator\mapred\staging\Administrator1702422322\.staging to 0700
	at org.apache.hadoop.fs.FileUtil.checkReturnValue(FileUtil.java:689)
	at org.apache.hadoop.fs.FileUtil.setPermission(FileUtil.java:662)
	at org.apache.hadoop.fs.RawLocalFileSystem.setPermission(RawLocalFileSystem.java:509)
	at org.apache.hadoop.fs.RawLocalFileSystem.mkdirs(RawLocalFileSystem.java:344)
	at org.apache.hadoop.fs.FilterFileSystem.mkdirs(FilterFileSystem.java:189)
	at org.apache.hadoop.mapreduce.JobSubmissionFiles.getStagingDir(JobSubmissionFiles.java:116)
	at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:856)
	at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:850)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:396)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
	at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:850)
	at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:824)
	at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1261)
	at org.conan.myhadoop.mr.WordCount.main(WordCount.java:78)

這個錯誤是win中開發特有的錯誤，文件權限問題，在Linux下可以正常運行。

解決方法是，修改/hadoop-1.0.3/src/core/org/apache/hadoop/fs/FileUtil.java文件

688-692行註釋，然後重新編譯源代碼，重新打一個hadoop.jar的包。


685 private static void checkReturnValue(boolean rv, File p,
686                                        FsPermission permission
687                                        ) throws IOException {
688     /*if (!rv) {
689       throw new IOException("Failed to set permissions of path: " + p +
690                             " to " +
691                             String.format("%04o", permission.toShort()));
692     }*/
693   }

我這裏自己打了一個hadoop-core-1.0.3.jar包，放到了lib下面。

我們還要替換maven中的hadoop類庫。


~ cp lib/hadoop-core-1.0.3.jar C:\Users\Administrator\.m2\repository\org\apache\hadoop\hadoop-core\1.0.3\hadoop-core-1.0.3.jar

再次啓動Java APP，控制檯輸出：


2013-9-30 19:50:49 org.apache.hadoop.util.NativeCodeLoader 
警告: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2013-9-30 19:50:49 org.apache.hadoop.mapred.JobClient copyAndConfigureFiles
警告: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
2013-9-30 19:50:49 org.apache.hadoop.mapred.JobClient copyAndConfigureFiles
警告: No job jar file set.  User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
2013-9-30 19:50:49 org.apache.hadoop.io.compress.snappy.LoadSnappy 
警告: Snappy native library not loaded
2013-9-30 19:50:49 org.apache.hadoop.mapred.FileInputFormat listStatus
信息: Total input paths to process : 4
2013-9-30 19:50:50 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息: Running job: job_local_0001
2013-9-30 19:50:50 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask runOldMapper
信息: numReduceTasks: 1
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: io.sort.mb = 100
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: data buffer = 79691776/99614720
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: record buffer = 262144/327680
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer flush
信息: Starting flush of map output
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer sortAndSpill
信息: Finished spill 0
2013-9-30 19:50:50 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_m_000000_0 is done. And is in the process of commiting
2013-9-30 19:50:51 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息:  map 0% reduce 0%
2013-9-30 19:50:53 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00003:0+119
2013-9-30 19:50:53 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_m_000000_0' done.
2013-9-30 19:50:53 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask runOldMapper
信息: numReduceTasks: 1
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: io.sort.mb = 100
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: data buffer = 79691776/99614720
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: record buffer = 262144/327680
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer flush
信息: Starting flush of map output
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer sortAndSpill
信息: Finished spill 0
2013-9-30 19:50:53 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_m_000001_0 is done. And is in the process of commiting
2013-9-30 19:50:54 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息:  map 100% reduce 0%
2013-9-30 19:50:56 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00000:0+113
2013-9-30 19:50:56 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_m_000001_0' done.
2013-9-30 19:50:56 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask runOldMapper
信息: numReduceTasks: 1
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: io.sort.mb = 100
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: data buffer = 79691776/99614720
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: record buffer = 262144/327680
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer flush
信息: Starting flush of map output
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer sortAndSpill
信息: Finished spill 0
2013-9-30 19:50:56 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_m_000002_0 is done. And is in the process of commiting
2013-9-30 19:50:59 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00001:0+110
2013-9-30 19:50:59 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00001:0+110
2013-9-30 19:50:59 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_m_000002_0' done.
2013-9-30 19:50:59 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask runOldMapper
信息: numReduceTasks: 1
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: io.sort.mb = 100
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: data buffer = 79691776/99614720
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: record buffer = 262144/327680
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer flush
信息: Starting flush of map output
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer sortAndSpill
信息: Finished spill 0
2013-9-30 19:50:59 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_m_000003_0 is done. And is in the process of commiting
2013-9-30 19:51:02 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00002:0+79
2013-9-30 19:51:02 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_m_000003_0' done.
2013-9-30 19:51:02 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:51:02 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: 
2013-9-30 19:51:02 org.apache.hadoop.mapred.Merger$MergeQueue merge
信息: Merging 4 sorted segments
2013-9-30 19:51:02 org.apache.hadoop.mapred.Merger$MergeQueue merge
信息: Down to the last merge-pass, with 4 segments left of total size: 442 bytes
2013-9-30 19:51:02 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: 
2013-9-30 19:51:02 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_r_000000_0 is done. And is in the process of commiting
2013-9-30 19:51:02 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: 
2013-9-30 19:51:02 org.apache.hadoop.mapred.Task commit
信息: Task attempt_local_0001_r_000000_0 is allowed to commit now
2013-9-30 19:51:02 org.apache.hadoop.mapred.FileOutputCommitter commitTask
信息: Saved output of task 'attempt_local_0001_r_000000_0' to hdfs://192.168.1.210:9000/user/hdfs/o_t_account/result
2013-9-30 19:51:05 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: reduce > reduce
2013-9-30 19:51:05 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_r_000000_0' done.
2013-9-30 19:51:06 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息:  map 100% reduce 100%
2013-9-30 19:51:06 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息: Job complete: job_local_0001
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息: Counters: 20
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:   File Input Format Counters 
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Bytes Read=421
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:   File Output Format Counters 
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Bytes Written=348
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:   FileSystemCounters
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     FILE_BYTES_READ=7377
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     HDFS_BYTES_READ=1535
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     FILE_BYTES_WRITTEN=209510
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     HDFS_BYTES_WRITTEN=348
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:   Map-Reduce Framework
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map output materialized bytes=458
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map input records=11
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Reduce shuffle bytes=0
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Spilled Records=30
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map output bytes=509
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Total committed heap usage (bytes)=1838546944
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map input bytes=421
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     SPLIT_RAW_BYTES=452
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Combine input records=22
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Reduce input records=15
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Reduce input groups=13
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Combine output records=15
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Reduce output records=13
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map output records=22

成功運行了wordcount程序，通過命令我們查看輸出結果


~ hadoop fs -ls hdfs://192.168.1.210:9000/user/hdfs/o_t_account/result

Found 2 items
-rw-r--r--   3 Administrator supergroup          0 2013-09-30 19:51 /user/hdfs/o_t_account/result/_SUCCESS
-rw-r--r--   3 Administrator supergroup        348 2013-09-30 19:51 /user/hdfs/o_t_account/result/part-00000

~ hadoop fs -cat hdfs://192.168.1.210:9000/user/hdfs/o_t_account/result/part-00000

1,[email protected],2013-04-22        1
10,[email protected],2013-04-23   1
11,[email protected],2013-04-23    1
17:21:24.0      5
2,[email protected],2013-04-22      1
20:21:39.0      6
3,[email protected],2013-04-22     1
4,[email protected],2013-04-22        1
5,[email protected],2013-04-22       1
6,[email protected],2013-04-22       1
7,[email protected],2013-04-23     1
8,[email protected],2013-04-23    1
9,[email protected],2013-04-23      1

這樣，我們就實現了在win7中的開發，通過Maven構建Hadoop依賴環境，在Eclipse中開發MapReduce的程序，然後運行JavaAPP。Hadoop應用會自動把我們的MR程序打成jar包，再上傳的遠程的hadoop環境中運行，返回日誌在Eclipse控制檯輸出。

7. 模板項目上傳github

https://github.com/bsspirit/maven_hadoop_template

大家可以下載這個項目，做爲開發的起點。

~ git clone https://github.com/bsspirit/maven_hadoop_template.git

我們完成第一步，下面就將正式進入MapReduce開發實踐。


Sep 30, 2013
Tags:
EclipseHadoopjavaMapReducemaven
Comments:
82 Comments

用Maven構建Hadoop項目

Hadoop家族系列文章，主要介紹Hadoop家族產品，常用的項目包括Hadoop, Hive, Pig, HBase, Sqoop, Mahout, Zookeeper, Avro, Ambari, Chukwa，新增加的項目包括，YARN, Hcatalog, Oozie, Cassandra, Hama, Whirr, Flume, Bigtop, Crunch, Hue等。

從2011年開始，中國進入大數據風起雲涌的時代，以Hadoop爲代表的家族軟件，佔據了大數據處理的廣闊地盤。開源界及廠商，所有數據軟件，無一不向Hadoop靠攏。Hadoop也從小衆的高富帥領域，變成了大數據開發的標準。在Hadoop原有技術基礎之上，出現了Hadoop家族產品，通過“大數據”概念不斷創新，推出科技進步。

作爲IT界的開發人員，我們也要跟上節奏，抓住機遇，跟着Hadoop一起雄起！

關於作者：

轉載請註明出處：
http://blog.fens.me/hadoop-maven-eclipse/

hadoop-maven

前言

Hadoop的MapReduce環境是一個複雜的編程環境，所以我們要儘可能地簡化構建MapReduce項目的過程。Maven是一個很不錯的自動化項目構建工具，通過Maven來幫助我們從複雜的環境配置中解脫出來，從而標準化開發過程。所以，寫MapReduce之前，讓我們先花點時間把刀磨快！！當然，除了Maven還有其他的選擇Gradle(推薦), Ivy….

後面將會有介紹幾篇MapReduce開發的文章，都要依賴於本文中Maven的構建的MapReduce環境。

目錄

  1. Maven介紹
  2. Maven安裝(win)
  3. Hadoop開發環境介紹
  4. 用Maven構建Hadoop環境
  5. MapReduce程序開發
  6. 模板項目上傳github

1. Maven介紹

Apache Maven，是一個Java的項目管理及自動構建工具，由Apache軟件基金會所提供。基於項目對象模型（縮寫：POM）概念，Maven利用一箇中央信息片斷能管理一個項目的構建、報告和文檔等步驟。曾是Jakarta項目的子項目，現爲獨立Apache項目。

maven的開發者在他們開發網站上指出，maven的目標是要使得項目的構建更加容易，它把編譯、打包、測試、發佈等開發過程中的不同環節有機的串聯了起來，併產生一致的、高質量的項目信息，使得項目成員能夠及時地得到反饋。maven有效地支持了測試優先、持續集成，體現了鼓勵溝通，及時反饋的軟件開發理念。如果說Ant的複用是建立在”拷貝–粘貼”的基礎上的，那麼Maven通過插件的機制實現了項目構建邏輯的真正複用。

2. Maven安裝(win)

下載Maven：http://maven.apache.org/download.cgi

下載最新的xxx-bin.zip文件，在win上解壓到 D:\toolkit\maven3

並把maven/bin目錄設置在環境變量PATH：

win7-maven

然後，打開命令行輸入mvn，我們會看到mvn命令的運行效果


~ C:\Users\Administrator>mvn
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.086s
[INFO] Finished at: Mon Sep 30 18:26:58 CST 2013
[INFO] Final Memory: 2M/179M
[INFO] ------------------------------------------------------------------------
[ERROR] No goals have been specified for this build. You must specify a valid lifecycle phase or a goal in the format : or :[:]:. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-class
es, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy. -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/NoGoalSpecifiedException

安裝Eclipse的Maven插件：Maven Integration for Eclipse

Maven的Eclipse插件配置

eclipse-maven

3. Hadoop開發環境介紹

hadoop-dev

如上圖所示，我們可以選擇在win中開發，也可以在linux中開發，本地啓動Hadoop或者遠程調用Hadoop，標配的工具都是Maven和Eclipse。

Hadoop集羣系統環境：

  • Linux: Ubuntu 12.04.2 LTS 64bit Server
  • Java: 1.6.0_29
  • Hadoop: hadoop-1.0.3，單節點，IP:192.168.1.210

4. 用Maven構建Hadoop環境

  • 1. 用Maven創建一個標準化的Java項目
  • 2. 導入項目到eclipse
  • 3. 增加hadoop依賴，修改pom.xml
  • 4. 下載依賴
  • 5. 從Hadoop集羣環境下載hadoop配置文件
  • 6. 配置本地host

1). 用Maven創建一個標準化的Java項目


~ D:\workspace\java>mvn archetype:generate -DarchetypeGroupId=org.apache.maven.archetypes -DgroupId=org.conan.myhadoop.mr
-DartifactId=myHadoop -DpackageName=org.conan.myhadoop.mr -Dversion=1.0-SNAPSHOT -DinteractiveMode=false
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] >>> maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom >>>
[INFO]
[INFO] <<< maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom <<<
[INFO]
[INFO] --- maven-archetype-plugin:2.2:generate (default-cli) @ standalone-pom ---
[INFO] Generating project in Batch mode
[INFO] No archetype defined. Using maven-archetype-quickstart (org.apache.maven.archetypes:maven-archetype-quickstart:1.
0)
Downloading: http://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archet
ype-quickstart-1.0.jar
Downloaded: http://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archety
pe-quickstart-1.0.jar (5 KB at 4.3 KB/sec)
Downloading: http://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archet
ype-quickstart-1.0.pom
Downloaded: http://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archety
pe-quickstart-1.0.pom (703 B at 1.6 KB/sec)
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Old (1.x) Archetype: maven-archetype-quickstart:1.0
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: groupId, Value: org.conan.myhadoop.mr
[INFO] Parameter: packageName, Value: org.conan.myhadoop.mr
[INFO] Parameter: package, Value: org.conan.myhadoop.mr
[INFO] Parameter: artifactId, Value: myHadoop
[INFO] Parameter: basedir, Value: D:\workspace\java
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] project created from Old (1.x) Archetype in dir: D:\workspace\java\myHadoop
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 8.896s
[INFO] Finished at: Sun Sep 29 20:57:07 CST 2013
[INFO] Final Memory: 9M/179M
[INFO] ------------------------------------------------------------------------

進入項目，執行mvn命令


~ D:\workspace\java>cd myHadoop
~ D:\workspace\java\myHadoop>mvn clean install
[INFO]
[INFO] --- maven-jar-plugin:2.3.2:jar (default-jar) @ myHadoop ---
[INFO] Building jar: D:\workspace\java\myHadoop\target\myHadoop-1.0-SNAPSHOT.jar
[INFO]
[INFO] --- maven-install-plugin:2.3.1:install (default-install) @ myHadoop ---
[INFO] Installing D:\workspace\java\myHadoop\target\myHadoop-1.0-SNAPSHOT.jar to C:\Users\Administrator\.m2\repository\o
rg\conan\myhadoop\mr\myHadoop\1.0-SNAPSHOT\myHadoop-1.0-SNAPSHOT.jar
[INFO] Installing D:\workspace\java\myHadoop\pom.xml to C:\Users\Administrator\.m2\repository\org\conan\myhadoop\mr\myHa
doop\1.0-SNAPSHOT\myHadoop-1.0-SNAPSHOT.pom
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4.348s
[INFO] Finished at: Sun Sep 29 20:58:43 CST 2013
[INFO] Final Memory: 11M/179M
[INFO] ------------------------------------------------------------------------

2). 導入項目到eclipse

我們創建好了一個基本的maven項目，然後導入到eclipse中。 這裏我們最好已安裝好了Maven的插件。

hadoop-eclipse

3). 增加hadoop依賴

這裏我使用hadoop-1.0.3版本，修改文件：pom.xml


~ vi pom.xml

<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.conan.myhadoop.mr</groupId>
<artifactId>myHadoop</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>myHadoop</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-core</artifactId>
<version>1.0.3</version>
</dependency>

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.4</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>

4). 下載依賴

下載依賴：

~ mvn clean install

在eclipse中刷新項目：

hadoop-eclipse-maven

項目的依賴程序，被自動加載的庫路徑下面。

5). 從Hadoop集羣環境下載hadoop配置文件

  • core-site.xml
  • hdfs-site.xml
  • mapred-site.xml

查看core-site.xml


<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
<property>
<name>fs.default.name</name>
<value>hdfs://master:9000</value>
</property>
<property>
<name>hadoop.tmp.dir</name>
<value>/home/conan/hadoop/tmp</value>
</property>
<property>
<name>io.sort.mb</name>
<value>256</value>
</property>
</configuration>

查看hdfs-site.xml


<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
<property>
<name>dfs.data.dir</name>
<value>/home/conan/hadoop/data</value>
</property>
<property>
<name>dfs.replication</name>
<value>1</value>
</property>
<property>
<name>dfs.permissions</name>
<value>false</value>
</property>
</configuration>

查看mapred-site.xml


<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<configuration>
<property>
<name>mapred.job.tracker</name>
<value>hdfs://master:9001</value>
</property>
</configuration>

保存在src/main/resources/hadoop目錄下面

hadoop-config

刪除原自動生成的文件：App.java和AppTest.java

6).配置本地host，增加master的域名指向


~ vi c:/Windows/System32/drivers/etc/hosts

192.168.1.210 master

6. MapReduce程序開發

編寫一個簡單的MapReduce程序，實現wordcount功能。

新一個Java文件：WordCount.java


package org.conan.myhadoop.mr;

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.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 WordCountMapper extends MapReduceBase implements Mapper<Object, Text, Text, IntWritable> {
        private final static IntWritable one = new IntWritable(1);
        private Text word = new Text();

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

        }
    }

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

        @Override
        public void reduce(Text key, Iterator values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
            int sum = 0;
            while (values.hasNext()) {
                sum += values.next().get();
            }
            result.set(sum);
            output.collect(key, result);
        }
    }

    public static void main(String[] args) throws Exception {
        String input = "hdfs://192.168.1.210:9000/user/hdfs/o_t_account";
        String output = "hdfs://192.168.1.210:9000/user/hdfs/o_t_account/result";

        JobConf conf = new JobConf(WordCount.class);
        conf.setJobName("WordCount");
        conf.addResource("classpath:/hadoop/core-site.xml");
        conf.addResource("classpath:/hadoop/hdfs-site.xml");
        conf.addResource("classpath:/hadoop/mapred-site.xml");

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

        conf.setMapperClass(WordCountMapper.class);
        conf.setCombinerClass(WordCountReducer.class);
        conf.setReducerClass(WordCountReducer.class);

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

        FileInputFormat.setInputPaths(conf, new Path(input));
        FileOutputFormat.setOutputPath(conf, new Path(output));

        JobClient.runJob(conf);
        System.exit(0);
    }

}

啓動Java APP.

控制檯錯誤


2013-9-30 19:25:02 org.apache.hadoop.util.NativeCodeLoader 
警告: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2013-9-30 19:25:02 org.apache.hadoop.security.UserGroupInformation doAs
嚴重: PriviledgedActionException as:Administrator cause:java.io.IOException: Failed to set permissions of path: \tmp\hadoop-Administrator\mapred\staging\Administrator1702422322\.staging to 0700
Exception in thread "main" java.io.IOException: Failed to set permissions of path: \tmp\hadoop-Administrator\mapred\staging\Administrator1702422322\.staging to 0700
	at org.apache.hadoop.fs.FileUtil.checkReturnValue(FileUtil.java:689)
	at org.apache.hadoop.fs.FileUtil.setPermission(FileUtil.java:662)
	at org.apache.hadoop.fs.RawLocalFileSystem.setPermission(RawLocalFileSystem.java:509)
	at org.apache.hadoop.fs.RawLocalFileSystem.mkdirs(RawLocalFileSystem.java:344)
	at org.apache.hadoop.fs.FilterFileSystem.mkdirs(FilterFileSystem.java:189)
	at org.apache.hadoop.mapreduce.JobSubmissionFiles.getStagingDir(JobSubmissionFiles.java:116)
	at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:856)
	at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:850)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:396)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
	at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:850)
	at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:824)
	at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1261)
	at org.conan.myhadoop.mr.WordCount.main(WordCount.java:78)

這個錯誤是win中開發特有的錯誤，文件權限問題，在Linux下可以正常運行。

解決方法是，修改/hadoop-1.0.3/src/core/org/apache/hadoop/fs/FileUtil.java文件

688-692行註釋，然後重新編譯源代碼，重新打一個hadoop.jar的包。


685 private static void checkReturnValue(boolean rv, File p,
686                                        FsPermission permission
687                                        ) throws IOException {
688     /*if (!rv) {
689       throw new IOException("Failed to set permissions of path: " + p +
690                             " to " +
691                             String.format("%04o", permission.toShort()));
692     }*/
693   }

我這裏自己打了一個hadoop-core-1.0.3.jar包，放到了lib下面。

我們還要替換maven中的hadoop類庫。


~ cp lib/hadoop-core-1.0.3.jar C:\Users\Administrator\.m2\repository\org\apache\hadoop\hadoop-core\1.0.3\hadoop-core-1.0.3.jar

再次啓動Java APP，控制檯輸出：


2013-9-30 19:50:49 org.apache.hadoop.util.NativeCodeLoader 
警告: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2013-9-30 19:50:49 org.apache.hadoop.mapred.JobClient copyAndConfigureFiles
警告: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
2013-9-30 19:50:49 org.apache.hadoop.mapred.JobClient copyAndConfigureFiles
警告: No job jar file set.  User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
2013-9-30 19:50:49 org.apache.hadoop.io.compress.snappy.LoadSnappy 
警告: Snappy native library not loaded
2013-9-30 19:50:49 org.apache.hadoop.mapred.FileInputFormat listStatus
信息: Total input paths to process : 4
2013-9-30 19:50:50 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息: Running job: job_local_0001
2013-9-30 19:50:50 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask runOldMapper
信息: numReduceTasks: 1
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: io.sort.mb = 100
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: data buffer = 79691776/99614720
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: record buffer = 262144/327680
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer flush
信息: Starting flush of map output
2013-9-30 19:50:50 org.apache.hadoop.mapred.MapTask$MapOutputBuffer sortAndSpill
信息: Finished spill 0
2013-9-30 19:50:50 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_m_000000_0 is done. And is in the process of commiting
2013-9-30 19:50:51 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息:  map 0% reduce 0%
2013-9-30 19:50:53 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00003:0+119
2013-9-30 19:50:53 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_m_000000_0' done.
2013-9-30 19:50:53 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask runOldMapper
信息: numReduceTasks: 1
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: io.sort.mb = 100
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: data buffer = 79691776/99614720
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: record buffer = 262144/327680
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer flush
信息: Starting flush of map output
2013-9-30 19:50:53 org.apache.hadoop.mapred.MapTask$MapOutputBuffer sortAndSpill
信息: Finished spill 0
2013-9-30 19:50:53 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_m_000001_0 is done. And is in the process of commiting
2013-9-30 19:50:54 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息:  map 100% reduce 0%
2013-9-30 19:50:56 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00000:0+113
2013-9-30 19:50:56 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_m_000001_0' done.
2013-9-30 19:50:56 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask runOldMapper
信息: numReduceTasks: 1
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: io.sort.mb = 100
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: data buffer = 79691776/99614720
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: record buffer = 262144/327680
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer flush
信息: Starting flush of map output
2013-9-30 19:50:56 org.apache.hadoop.mapred.MapTask$MapOutputBuffer sortAndSpill
信息: Finished spill 0
2013-9-30 19:50:56 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_m_000002_0 is done. And is in the process of commiting
2013-9-30 19:50:59 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00001:0+110
2013-9-30 19:50:59 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00001:0+110
2013-9-30 19:50:59 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_m_000002_0' done.
2013-9-30 19:50:59 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask runOldMapper
信息: numReduceTasks: 1
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: io.sort.mb = 100
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: data buffer = 79691776/99614720
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer 
信息: record buffer = 262144/327680
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer flush
信息: Starting flush of map output
2013-9-30 19:50:59 org.apache.hadoop.mapred.MapTask$MapOutputBuffer sortAndSpill
信息: Finished spill 0
2013-9-30 19:50:59 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_m_000003_0 is done. And is in the process of commiting
2013-9-30 19:51:02 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: hdfs://192.168.1.210:9000/user/hdfs/o_t_account/part-m-00002:0+79
2013-9-30 19:51:02 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_m_000003_0' done.
2013-9-30 19:51:02 org.apache.hadoop.mapred.Task initialize
信息:  Using ResourceCalculatorPlugin : null
2013-9-30 19:51:02 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: 
2013-9-30 19:51:02 org.apache.hadoop.mapred.Merger$MergeQueue merge
信息: Merging 4 sorted segments
2013-9-30 19:51:02 org.apache.hadoop.mapred.Merger$MergeQueue merge
信息: Down to the last merge-pass, with 4 segments left of total size: 442 bytes
2013-9-30 19:51:02 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: 
2013-9-30 19:51:02 org.apache.hadoop.mapred.Task done
信息: Task:attempt_local_0001_r_000000_0 is done. And is in the process of commiting
2013-9-30 19:51:02 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: 
2013-9-30 19:51:02 org.apache.hadoop.mapred.Task commit
信息: Task attempt_local_0001_r_000000_0 is allowed to commit now
2013-9-30 19:51:02 org.apache.hadoop.mapred.FileOutputCommitter commitTask
信息: Saved output of task 'attempt_local_0001_r_000000_0' to hdfs://192.168.1.210:9000/user/hdfs/o_t_account/result
2013-9-30 19:51:05 org.apache.hadoop.mapred.LocalJobRunner$Job statusUpdate
信息: reduce > reduce
2013-9-30 19:51:05 org.apache.hadoop.mapred.Task sendDone
信息: Task 'attempt_local_0001_r_000000_0' done.
2013-9-30 19:51:06 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息:  map 100% reduce 100%
2013-9-30 19:51:06 org.apache.hadoop.mapred.JobClient monitorAndPrintJob
信息: Job complete: job_local_0001
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息: Counters: 20
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:   File Input Format Counters 
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Bytes Read=421
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:   File Output Format Counters 
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Bytes Written=348
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:   FileSystemCounters
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     FILE_BYTES_READ=7377
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     HDFS_BYTES_READ=1535
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     FILE_BYTES_WRITTEN=209510
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     HDFS_BYTES_WRITTEN=348
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:   Map-Reduce Framework
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map output materialized bytes=458
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map input records=11
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Reduce shuffle bytes=0
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Spilled Records=30
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map output bytes=509
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Total committed heap usage (bytes)=1838546944
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map input bytes=421
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     SPLIT_RAW_BYTES=452
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Combine input records=22
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Reduce input records=15
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Reduce input groups=13
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Combine output records=15
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Reduce output records=13
2013-9-30 19:51:06 org.apache.hadoop.mapred.Counters log
信息:     Map output records=22

成功運行了wordcount程序，通過命令我們查看輸出結果


~ hadoop fs -ls hdfs://192.168.1.210:9000/user/hdfs/o_t_account/result

Found 2 items
-rw-r--r--   3 Administrator supergroup          0 2013-09-30 19:51 /user/hdfs/o_t_account/result/_SUCCESS
-rw-r--r--   3 Administrator supergroup        348 2013-09-30 19:51 /user/hdfs/o_t_account/result/part-00000

~ hadoop fs -cat hdfs://192.168.1.210:9000/user/hdfs/o_t_account/result/part-00000

1,[email protected],2013-04-22        1
10,[email protected],2013-04-23   1
11,[email protected],2013-04-23    1
17:21:24.0      5
2,[email protected],2013-04-22      1
20:21:39.0      6
3,[email protected],2013-04-22     1
4,[email protected],2013-04-22        1
5,[email protected],2013-04-22       1
6,[email protected],2013-04-22       1
7,[email protected],2013-04-23     1
8,[email protected],2013-04-23    1
9,[email protected],2013-04-23      1

這樣，我們就實現了在win7中的開發，通過Maven構建Hadoop依賴環境，在Eclipse中開發MapReduce的程序，然後運行JavaAPP。Hadoop應用會自動把我們的MR程序打成jar包，再上傳的遠程的hadoop環境中運行，返回日誌在Eclipse控制檯輸出。

7. 模板項目上傳github

https://github.com/bsspirit/maven_hadoop_template

大家可以下載這個項目，做爲開發的起點。

~ git clone https://github.com/bsspirit/maven_hadoop_template.git

我們完成第一步，下面就將正式進入MapReduce開發實踐。

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