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环境:Windows8.1,Eclipse
用Hadoop自带的wordcount示例
hadoop2.7.0
hadoop-eclipse-plugin-2.7.0.jar //Eclipse的插件,需要对应Hadoop当前版本
基本步骤有很多博客已经提及,就不再赘述
1. 将hadoop-eclipse-plugin-2.7.0.jar放入Eclipse的plugins目录,启动Eclipse
2. 配置Eclipse的Hadoop location信息
3. 新建MapReduce Project
4. 将wordcount的代码拷贝进去
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.hadoop.examples; import java.io.IOException; import java.util.StringTokenizer; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.util.GenericOptionsParser; public class WordCount { public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable>{ private final static IntWritable one = new IntWritable(1); private Text word = new Text(); public void map(Object key, Text value, Context context ) throws IOException, InterruptedException { StringTokenizer itr = new StringTokenizer(value.toString()); while (itr.hasMoreTokens()) { word.set(itr.nextToken()); context.write(word, one); } } } public static class IntSumReducer extends Reducer<Text,IntWritable,Text,IntWritable> { private IntWritable result = new IntWritable(); public void reduce(Text key, Iterable<IntWritable> values, Context context ) throws IOException, InterruptedException { int sum = 0; for (IntWritable val : values) { sum += val.get(); } result.set(sum); context.write(key, result); } } public static void main(String[] args) throws Exception { Configuration conf = new Configuration(); conf.set("mapred.job.tracker", "192.168.1.150:9001"); conf.set("yarn.resourcemanager.address", "192.168.1.150:8032"); String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs(); if (otherArgs.length < 2) { System.err.println("Usage: wordcount <in> [<in>...] <out>"); System.exit(2); } Job job = Job.getInstance(conf, "word count"); job.setJarByClass(WordCount.class); job.setMapperClass(TokenizerMapper.class); job.setCombinerClass(IntSumReducer.class); job.setReducerClass(IntSumReducer.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); for (int i = 0; i < otherArgs.length - 1; ++i) { FileInputFormat.addInputPath(job, new Path(otherArgs[i])); } FileOutputFormat.setOutputPath(job, new Path(otherArgs[otherArgs.length - 1])); System.exit(job.waitForCompletion(true) ? 0 : 1); } }
Main方法的头三行代码,需要自己来配置
5. 将部署好的Hadoop集群中的配置文件拷贝至项目中
log4j.properties必须要配置,不然提交任务至集群时,Console无法显示信息,以下是我的配置
log4j.rootLogger=DEBUG, CA log4j.appender.CA=org.apache.log4j.ConsoleAppender log4j.appender.CA.layout=org.apache.log4j.PatternLayout log4j.appender.CA.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n
6. 右键点击WordCount.java -> Run as -> Run on Hadoop
错误1:
org.apache.hadoop.util.Shell$ExitCodeException: /bin/bash: line 0: fg: no job control
Hadoop读取Windows和Linux系统变量时的引发的问题,有几种解决方案,嫌麻烦不想重新编译整个Hadoop就在本项目中直接重写来解决
在Hadoop的源代码中找到YARNRunner.java,拷贝至项目中,项目中的Package要和Hadoop源代码中的一样,运行时才会覆盖
修改YARNRunner.java
(1)修改读取Windows系统变量的方式
注释掉的代码是原来的代码
(2)新增一个处理Windows系统变量的方法
private void replaceEnvironment(Map<String, String> environment) { String tmpClassPath = environment.get("CLASSPATH"); tmpClassPath=tmpClassPath.replaceAll(";", ":"); tmpClassPath=tmpClassPath.replaceAll("%PWD%", "\\$PWD"); tmpClassPath=tmpClassPath.replaceAll("%HADOOP_MAPRED_HOME%", "\\$HADOOP_MAPRED_HOME"); tmpClassPath= tmpClassPath.replaceAll("\\\\", "/" ); environment.put("CLASSPATH",tmpClassPath); }
在此处使用
错误2:
exited with exitCode: 1 due to: Exception from container-launch
Diagnostics: Exception from container-launch.
修改项目中的mapred-site.xml,增加以下内容
<property> <name>mapreduce.application.classpath</name> <value> $HADOOP_CONF_DIR, $HADOOP_COMMON_HOME/share/hadoop/common/*, $HADOOP_COMMON_HOME/share/hadoop/common/lib/*, $HADOOP_HDFS_HOME/share/hadoop/hdfs/*, $HADOOP_HDFS_HOME/share/hadoop/hdfs/lib/*, $HADOOP_MAPRED_HOME/share/hadoop/mapreduce/*, $HADOOP_MAPRED_HOME/share/hadoop/mapreduce/lib/*, $HADOOP_YARN_HOME/share/hadoop/yarn/*, $HADOOP_YARN_HOME/share/hadoop/yarn/lib/* </value> </property>
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原文地址:http://www.cnblogs.com/dopeter/p/4630791.html