Como compilar o código-fonte do MapReduce no Hadoop 2.7.0?
estou a executar o Hadoop 2.7.0 no ubuntu 14.0.2 O. S., e crio wordcount.java with nano text editor which the source code is copy from Apache Hadoop 2.7.0 Document .
Depois de compilar o número de palavras.java com este comando javac -classpath hadoop-2.7.0-core.jar -d MyJava wordcount.java
, Aqui estão as mensagens de erro que recebi.
public class WordCount2 {
^
wordcount_v2.java:11: error: package org.apache.hadoop.conf does not exist
import org.apache.hadoop.conf.Configuration;
^
wordcount_v2.java:12: error: package org.apache.hadoop.fs does not exist
import org.apache.hadoop.fs.Path;
^
wordcount_v2.java:13: error: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.IntWritable;
^
wordcount_v2.java:14: error: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.Text;
^
wordcount_v2.java:15: error: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Job;
^
wordcount_v2.java:16: error: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Mapper;
^
wordcount_v2.java:17: error: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Reducer;
^
wordcount_v2.java:18: error: package org.apache.hadoop.mapreduce.lib.input does not exist
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
^
wordcount_v2.java:19: error: package org.apache.hadoop.mapreduce.lib.output does not exist
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
^
wordcount_v2.java:20: error: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Counter;
^
wordcount_v2.java:21: error: package org.apache.hadoop.util does not exist
import org.apache.hadoop.util.GenericOptionsParser;
^
wordcount_v2.java:22: error: package org.apache.hadoop.util does not exist
import org.apache.hadoop.util.StringUtils;
^
wordcount_v2.java:27: error: cannot find symbol
extends Mapper<Object, Text, Text, IntWritable>{
^
symbol: class Mapper
location: class WordCount2
wordcount_v2.java:27: error: cannot find symbol
extends Mapper<Object, Text, Text, IntWritable>{
^
symbol: class Text
location: class WordCount2
wordcount_v2.java:27: error: cannot find symbol
extends Mapper<Object, Text, Text, IntWritable>{
^
symbol: class Text
location: class WordCount2
wordcount_v2.java:27: error: cannot find symbol
extends Mapper<Object, Text, Text, IntWritable>{
^
symbol: class IntWritable
location: class WordCount2
wordcount_v2.java:31: error: cannot find symbol
private final static IntWritable one = new IntWritable(1);
^
symbol: class IntWritable
location: class TokenizerMapper
wordcount_v2.java:32: error: cannot find symbol
private Text word = new Text();
^
symbol: class Text
location: class TokenizerMapper
wordcount_v2.java:37: error: cannot find symbol
private Configuration conf;
^
symbol: class Configuration
location: class TokenizerMapper
wordcount_v2.java:41: error: cannot find symbol
public void setup(Context context) throws IOException,
^
symbol: class Context
location: class TokenizerMapper
wordcount_v2.java:69: error: cannot find symbol
public void map(Object key, Text value, Context context
^
symbol: class Text
location: class TokenizerMapper
wordcount_v2.java:69: error: cannot find symbol
public void map(Object key, Text value, Context context
^
symbol: class Context
location: class TokenizerMapper
wordcount_v2.java:88: error: cannot find symbol
extends Reducer<Text,IntWritable,Text,IntWritable> {
^
symbol: class Reducer
location: class WordCount2
wordcount_v2.java:88: error: cannot find symbol
extends Reducer<Text,IntWritable,Text,IntWritable> {
^
symbol: class Text
location: class WordCount2
wordcount_v2.java:88: error: cannot find symbol
extends Reducer<Text,IntWritable,Text,IntWritable> {
^
symbol: class IntWritable
location: class WordCount2
wordcount_v2.java:88: error: cannot find symbol
extends Reducer<Text,IntWritable,Text,IntWritable> {
^
symbol: class Text
location: class WordCount2
wordcount_v2.java:88: error: cannot find symbol
extends Reducer<Text,IntWritable,Text,IntWritable> {
^
symbol: class IntWritable
location: class WordCount2
wordcount_v2.java:89: error: cannot find symbol
private IntWritable result = new IntWritable();
^
symbol: class IntWritable
location: class IntSumReducer
wordcount_v2.java:91: error: cannot find symbol
public void reduce(Text key, Iterable<IntWritable> values,
^
symbol: class Text
location: class IntSumReducer
wordcount_v2.java:91: error: cannot find symbol
public void reduce(Text key, Iterable<IntWritable> values,
^
symbol: class IntWritable
location: class IntSumReducer
wordcount_v2.java:92: error: cannot find symbol
Context context
^
symbol: class Context
location: class IntSumReducer
wordcount_v2.java:31: error: cannot find symbol
private final static IntWritable one = new IntWritable(1);
^
symbol: class IntWritable
location: class TokenizerMapper
wordcount_v2.java:32: error: cannot find symbol
private Text word = new Text();
^
symbol: class Text
location: class TokenizerMapper
wordcount_v2.java:40: error: method does not override or implement a method from a supertype
@Override
^
wordcount_v2.java:46: error: cannot find symbol
URI[] patternsURIs = Job.getInstance(conf).getCacheFiles();
^
symbol: variable Job
location: class TokenizerMapper
wordcount_v2.java:48: error: cannot find symbol
Path patternsPath = new Path(patternsURI.getPath());
^
symbol: class Path
location: class TokenizerMapper
wordcount_v2.java:48: error: cannot find symbol
Path patternsPath = new Path(patternsURI.getPath());
^
symbol: class Path
location: class TokenizerMapper
wordcount_v2.java:64: error: cannot find symbol
+ StringUtils.stringifyException(ioe));
^
symbol: variable StringUtils
location: class TokenizerMapper
wordcount_v2.java:68: error: method does not override or implement a method from a supertype
@Override
^
wordcount_v2.java:80: error: cannot find symbol
Counter counter = context.getCounter(CountersEnum.class.getName(),
^
symbol: class Counter
location: class TokenizerMapper
wordcount_v2.java:89: error: cannot find symbol
private IntWritable result = new IntWritable();
^
symbol: class IntWritable
location: class IntSumReducer
wordcount_v2.java:95: error: cannot find symbol
for (IntWritable val : values) {
^
symbol: class IntWritable
location: class IntSumReducer
wordcount_v2.java:104: error: cannot find symbol
Configuration conf = new Configuration();
^
symbol: class Configuration
location: class WordCount2
wordcount_v2.java:104: error: cannot find symbol
Configuration conf = new Configuration();
^
symbol: class Configuration
location: class WordCount2
wordcount_v2.java:105: error: cannot find symbol
GenericOptionsParser optionParser = new GenericOptionsParser(conf, args);
^
symbol: class GenericOptionsParser
location: class WordCount2
wordcount_v2.java:105: error: cannot find symbol
GenericOptionsParser optionParser = new GenericOptionsParser(conf, args);
^
symbol: class GenericOptionsParser
location: class WordCount2
wordcount_v2.java:111: error: cannot find symbol
Job job = Job.getInstance(conf, "word count");
^
symbol: class Job
location: class WordCount2
wordcount_v2.java:111: error: cannot find symbol
Job job = Job.getInstance(conf, "word count");
^
symbol: variable Job
location: class WordCount2
wordcount_v2.java:116: error: cannot find symbol
job.setOutputKeyClass(Text.class);
^
symbol: class Text
location: class WordCount2
wordcount_v2.java:117: error: cannot find symbol
job.setOutputValueClass(IntWritable.class);
^
symbol: class IntWritable
location: class WordCount2
wordcount_v2.java:122: error: cannot find symbol
job.addCacheFile(new Path(remainingArgs[++i]).toUri());
^
symbol: class Path
location: class WordCount2
wordcount_v2.java:128: error: cannot find symbol
FileInputFormat.addInputPath(job, new Path(otherArgs.get(0)));
^
symbol: class Path
location: class WordCount2
wordcount_v2.java:128: error: cannot find symbol
FileInputFormat.addInputPath(job, new Path(otherArgs.get(0)));
^
symbol: variable FileInputFormat
location: class WordCount2
wordcount_v2.java:129: error: cannot find symbol
FileOutputFormat.setOutputPath(job, new Path(otherArgs.get(1)));
^
symbol: class Path
location: class WordCount2
wordcount_v2.java:129: error: cannot find symbol
FileOutputFormat.setOutputPath(job, new Path(otherArgs.get(1)));
^
symbol: variable FileOutputFormat
location: class WordCount2
56 errors
Pergunto - me como é que isso aconteceu. A minha versão JDK é 1.8.0_45
6 answers
Use o Maven para a gestão de dependências. O que você está tentando fazer aqui é algo que está em um nível HelloWorld.
Consulte a seguinte ligação para configurar o maven para um projecto Hadoop: Maven para o Hadoop
Esta não é a forma correcta de executar o programa de redução de mapas do hadoop Primeiro você tem que Instalar Hadoop e configurar isso guia de instalação nesta ligação http://www.bogotobogo.com/Hadoop/BigData_hadoop_Install_on_ubuntu_single_node_cluster.php
Depois disso, esta é a contagem de palavras. exemploSiga todas as instruções passo a passo...então o seu programa será executado..
Estes erros são devidos à dependência, você deve adicionar mais algumas bibliotecas para compilar sem problemas. As bibliotecas podem ser encontradas nas sub-pastas HADOOP_HOME
como ~/share/hadoop/
Você não importou as classes no seu código para as quais os erros estão vindo.
Eu acho que você tem que adicionar {[[0]} ao seu classpath e importar todas essas classes no seu código e compilar novamente e ele deve funcionar.
Pode tomar qualquer versão hadoop-core-x.y.z.jar
que não seja específica apenas para hadoop-core-1.0.4.jar
.
org.apache.hadoop:hadoop-common:2.7.0
org.apache.hadoop:hadoop-client:2.7.0
org.apache.hadoop:hadoop-auth:2.7.0
org.apache.hadoop:hadoop-hdfs:2.7.0
No mínimo. Boa sorte!
Não é necessário descarregar nenhum ficheiro jar da versão anterior. Você deve executar um comando como
javac -classpath `yarn classpath` -d \path-to-where-class-file-to-be-stored\ wordcount.java
P. S. Nota-Se o carácter Tild ` (uma tecla acima do tab e da esquerda para 1) antes e depois do fecho do fio.