hadoop:将WordCount打包成独立运行的jar包

hadoop示例中的WordCount程序，很多教程上都是推荐以下二种运行方式：

1.将生成的jar包，复制到hadoop集群中的节点，然后运行

$HADOOP_HOME/bin/hadoop xxx.jar xxx.WordCount /input/xxx.txt /output

2.或者直接在IDE环境中调试(参见eclipse/intellij idea 远程调试hadoop 2.6.0)

但是生产环境中，更多的情况是：没有ide环境，且各应用最终生成的jar包部署在应用服务器上（应用服务器并非hadoop集群中的服务器节点），所以需要jar能独立运行并能连接到hadoop环境，以下是关键点：

1. pom.xml中将WordCount所依赖的jar包依赖项，全添加进来（这样最终运行时，这些jar包就不用依赖ide或hadoop运行环境）

2. 参考maven: 打包可运行的jar包(java application)及依赖项处理 一文将依赖的jar包导出，且通过maven插件自动修改MANIFEST.MF中的Main-Class信息

3. core-site.xml要复制到maven项目的resources目录下（这样打包后，xml会复制到classpath下，运行时，根据这个配置文件，WordCount就能知道去连哪里的hadoop）

4. 部署时，将最终生成的WordCount jar包及依赖的lib包，全上传到应用服务器

然后就能直接以类似

java -jar hadoop-helloworld.jar /jimmy/input/README.txt /jimmy/output 运行

最后附几个关键文件内容：

a. pom.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <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/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>

     <groupId>cn.cnblogs.yjmyzz</groupId>
     <artifactId>hadoop-helloworld</artifactId>
     <version>1.0</version>

     <dependencies>
         <dependency>
             <groupId>org.apache.hadoop</groupId>
             <artifactId>hadoop-common</artifactId>
             <version>2.6.0</version>
         </dependency>
         <dependency>
             <groupId>org.apache.hadoop</groupId>
             <artifactId>hadoop-hdfs</artifactId>
             <version>2.6.0</version>
         </dependency>
         <dependency>
             <groupId>org.apache.hadoop</groupId>
             <artifactId>hadoop-mapreduce-client-jobclient</artifactId>
             <version>2.6.0</version>
         </dependency>
         <dependency>
             <groupId>commons-cli</groupId>
             <artifactId>commons-cli</artifactId>
             <version>1.2</version>
         </dependency>
     </dependencies>

     <build>
         <finalName>${project.artifactId}</finalName>

         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-jar-plugin</artifactId>
                 <configuration>
                     <archive>
                         <manifest>
                             <mainClass>cn.cnblogs.yjmyzz.WordCount</mainClass>
                             <addClasspath>true</addClasspath>
                             <classpathPrefix>lib/</classpathPrefix>
                         </manifest>
                     </archive>
                     <classesDirectory>
                     </classesDirectory>
                 </configuration>
             </plugin>
         </plugins>
     </build>

     <!--mvn dependency:copy-dependencies -DoutputDirectory=target/lib-->

 </project>

b.\META-INF\MANIFEST.MF内容

Manifest-Version: 1.0
Built-By: jimmy
Build-Jdk: 1.7.0_09
Class-Path: lib/hadoop-common-2.6.0.jar lib/hadoop-annotations-2.6.0.j
 ar lib/guava-11.0.2.jar lib/commons-math3-3.1.1.jar lib/xmlenc-0.52.j
 ar lib/commons-httpclient-3.1.jar lib/commons-codec-1.4.jar lib/commo
 ns-io-2.4.jar lib/commons-net-3.1.jar lib/commons-collections-3.2.1.j
 ar lib/servlet-api-2.5.jar lib/jetty-6.1.26.jar lib/jetty-util-6.1.26
 .jar lib/jersey-core-1.9.jar lib/jersey-json-1.9.jar lib/jettison-1.1
 .jar lib/jaxb-impl-2.2.3-1.jar lib/jaxb-api-2.2.2.jar lib/stax-api-1.
 0-2.jar lib/activation-1.1.jar lib/jackson-jaxrs-1.8.3.jar lib/jackso
 n-xc-1.8.3.jar lib/jersey-server-1.9.jar lib/asm-3.1.jar lib/jasper-c
 ompiler-5.5.23.jar lib/jasper-runtime-5.5.23.jar lib/jsp-api-2.1.jar
 lib/commons-el-1.0.jar lib/commons-logging-1.1.3.jar lib/log4j-1.2.17
 .jar lib/jets3t-0.9.0.jar lib/httpclient-4.1.2.jar lib/httpcore-4.1.2
 .jar lib/java-xmlbuilder-0.4.jar lib/commons-lang-2.6.jar lib/commons
 -configuration-1.6.jar lib/commons-digester-1.8.jar lib/commons-beanu
 tils-1.7.0.jar lib/commons-beanutils-core-1.8.0.jar lib/slf4j-api-1.7
 .5.jar lib/slf4j-log4j12-1.7.5.jar lib/jackson-core-asl-1.9.13.jar li
 b/jackson-mapper-asl-1.9.13.jar lib/avro-1.7.4.jar lib/paranamer-2.3.
 jar lib/snappy-java-1.0.4.1.jar lib/protobuf-java-2.5.0.jar lib/gson-
 2.2.4.jar lib/hadoop-auth-2.6.0.jar lib/apacheds-kerberos-codec-2.0.0
 -M15.jar lib/apacheds-i18n-2.0.0-M15.jar lib/api-asn1-api-1.0.0-M20.j
 ar lib/api-util-1.0.0-M20.jar lib/curator-framework-2.6.0.jar lib/jsc
 h-0.1.42.jar lib/curator-client-2.6.0.jar lib/curator-recipes-2.6.0.j
 ar lib/jsr305-1.3.9.jar lib/htrace-core-3.0.4.jar lib/zookeeper-3.4.6
 .jar lib/commons-compress-1.4.1.jar lib/xz-1.0.jar lib/hadoop-hdfs-2.
 6.0.jar lib/commons-daemon-1.0.13.jar lib/netty-3.6.2.Final.jar lib/x
 ercesImpl-2.9.1.jar lib/xml-apis-1.3.04.jar lib/hadoop-mapreduce-clie
 nt-jobclient-2.6.0.jar lib/hadoop-mapreduce-client-common-2.6.0.jar l
 ib/hadoop-yarn-common-2.6.0.jar lib/hadoop-yarn-api-2.6.0.jar lib/jer
 sey-client-1.9.jar lib/jersey-guice-1.9.jar lib/hadoop-yarn-client-2.
 6.0.jar lib/hadoop-mapreduce-client-core-2.6.0.jar lib/hadoop-yarn-se
 rver-common-2.6.0.jar lib/hadoop-mapreduce-client-shuffle-2.6.0.jar l
 ib/hadoop-yarn-server-nodemanager-2.6.0.jar lib/leveldbjni-all-1.8.ja
 r lib/guice-servlet-3.0.jar lib/guice-3.0.jar lib/javax.inject-1.jar
 lib/aopalliance-1.0.jar lib/commons-cli-1.2.jar
Created-By: Apache Maven 3.2.3
Main-Class: cn.cnblogs.yjmyzz.WordCount
Archiver-Version: Plexus Archiver

运行截图：