我在运行修改版的 Wordcount 程序时遇到错误(添加了映射器逻辑以将符号与单词分开)。
错误:java.lang.RuntimeException:java.lang.ClassNotFoundException:类 wcount.WordCount$TokenizerMapper
操作系统:HortonWorks Sandbox hosting 2.6 Hadoop 版本 这是我所做的-
- 修改 Wordcount.java 以引入映射器逻辑
- 使用命令编译了 Wordcount.java
javac -classpath/home/test_user/jars/commons-cli-1.2.jar:/home/test_user/jars/hadoop-common-2.6.0.2.2.0.0-2041.jar:/home/test_user/jars/hadoop-mapreduce-client-core-2.6.0.2.2.0.0-2041.jar -d/home/test_user/hadoopjar/wordcountclass -Xlint:deprecation WordCount.java
使用
jar cvf wordcount.jar wcount
创建了 WordCount.jar(其中 wcount 是包含所有 3 个类(wordcount、tokenizer 和 intsumreducer)的文件夹。 这是 jar 文件的样子计数 wcount/WordCount.class 类 wcount/WordCount$TokenizerMapper.class 类 wcount/WordCount$intsumreducer.class
使用命令运行它 -
hadoop jar wordcount.jar WordCount/home/user/test_user/wordcount/wordcount.txt/home/user/test_user/wordcount/out8
尝试运行 Map 作业后出错 Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class wcount.WordCount$TokenizerMapper
代码是
package wcount;
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());
char[] chararray = {'(' , ')' , ';' , ':' , '.' , '/' , '{' , '}' , ']' , ']'};
String temp;
while (itr.hasMoreTokens())
{
temp = itr.nextToken();
for (short i = 0; i < chararray.length; i++)
{
if (temp.charAt(0) == chararray[i])
{
temp = temp.substring(1);
}
if (temp.charAt(temp.length() - 1) == chararray[i])
{
temp = temp.substring(0, temp.length() - 1);
}
}
word.set(temp);
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();
String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
if (otherArgs.length < 2) {
System.err.println("Usage: wordcount <in> [<in>...] <out>");
System.exit(2);
}
Job job = new Job(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);
}
}
最佳答案
您没有在作业设置中设置任何 InputFormatter,因此默认情况下您的输入格式化程序是 TextInputFormatter。所以这份工作可能需要一个LongWritable
而不是普通的 Object
.您可以尝试更改 extends Mapper<Object
吗?至 extends Mapper<LongWritable
还有map(Object key
至 map(LongWritable key
?
关于java - 在 Horton Works 沙盒上运行 Modified Wordcount 程序时需要帮助。,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28153347/