线程“main”java.lang.classnotfoundexception中出现异常:wordcount

eaf3rand  于 2021-06-03  发布在  Hadoop
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我现在想创建一个hadoop的示例节点。所以我遵循这个教程。我在终端中运行了以下命令:

hduser@ubuntu:/usr/local/hadoop$ bin/hadoop jar WordCount.jar geekyomega.WordCount /user/hduser/gutenberg /user/hduser/gutenberg-output

一切都很顺利,直到我遇到这个错误:

Exception in thread "main" java.lang.ClassNotFoundException: WordCount
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:270)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:153)

我试图用下面的代码运行这个例子,我从这里得到了。以下是我的代码版本:

package geekyomega;

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.waitForCompletion(true);
 }

}

我以为我的问题是作业示例化。所以我做了如下改变:

Job job = new Job(conf, "wordcount");

以下大写版本:

Job job = new Job(conf, "WordCount");

但这没用。有人知道什么能帮我吗?
谢谢,怪人
我不想运行wordcount的教程版本。我所做的是在eclipse中创建项目,将hadoopjar添加到其中,并将其导出为jar文件。

cgh8pdjw

cgh8pdjw1#

在添加包的同时,在程序的job config部分中也添加以下行:
job.setjarbyclass(wordcount.class);

qlfbtfca

qlfbtfca2#

你的类名是geekyomega.wordcount
您没有附加包名称。在命令行中,在jar文件名之后,给出作业类的完全限定名。

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