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我是Hadoop的新手,并试图运行Map Reduce程序,它的字数很高,我得到以下错误了java.lang.RuntimeException:抛出java.lang.ClassNotFoundException:wordcount_classes.WordCount $地图和WordCount.java
import java.io.IOException;
import java.util.*;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
public class WordCount {
public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
String line = value.toString();
StringTokenizer tokenizer = new StringTokenizer(line);
while (tokenizer.hasMoreTokens()) {
word.set(tokenizer.nextToken());
context.write(word, one);
}
}
}
public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {
public void reduce(Text key, Iterable<IntWritable> values, Context context)
throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
context.write(key, new IntWritable(sum));
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
Job job = new Job(conf, "wordcount");
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.setJarByClass(WordCount.class);
job.waitForCompletion(true);
}
wordcount_classes目录的内容是
-rw-r--r-- 1 sagar supergroup 1855 2014-10-03 13:15 /user/sagar /wordcount_classes/WordCount$Map.class
-rw-r--r-- 1 sagar supergroup 1627 2014-10-03 13:15 /user/sagar/wordcount_classes/WordCount$Reduce.class
-rw-r--r-- 1 sagar supergroup 1453 2014-10-03 13:14 /user/sagar/wordcount_classes/WordCount.class
-rw-r--r-- 1 sagar supergroup 3109 2014-10-03 13:15 /user/sagar/wordcount_classes/wordcount.jar
}
,我用下面的命令编译程序
hadoop jar wordcount_classes/wordcount.jar wordcount_classes/WordCount input r1
这些输入和输出目录应该位于hdfs文件或其他位置? – Sagar 2014-10-03 11:06:44
输入应该是位于hdfs中的输入源文件,输出是hdfs中的目录,但不应该创建,输出将由程序本身创建。如果您的问题已修复,请告知我 – 2014-10-03 11:08:30
如何知道在hdfs中创建的目录的文件系统路径? – Sagar 2014-10-03 11:14:35