Question

我是Hadoop的新手。我已经在虚拟机中安装了oracle虚拟盒并安装了hortonworks沙箱的映像。此外，我已经在eclipse中编写了wordcount程序并尝试在虚拟机中运行它。但是我得到了一个异常树。我也在发布程序和错误树。

public class WordCount {

public static class Map extends MapReduceBase implements
        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,
            OutputCollector<Text, IntWritable> output, Reporter reporter)
            throws IOException {
        String line = value.toString();
        StringTokenizer tokenizer = new StringTokenizer(line);
        while (tokenizer.hasMoreTokens()) {
            word.set(tokenizer.nextToken());
            output.collect(word, one);
        }
    }
}

public static class Reduce extends MapReduceBase implements
        Reducer<Text, IntWritable, Text, IntWritable> {
    public void reduce(Text key, Iterator<IntWritable> values,
            OutputCollector<Text, IntWritable> output, Reporter reporter)
            throws IOException {
        int sum = 0;
        while (values.hasNext()) {
            sum += values.next().get();
        }
        output.collect(key, new IntWritable(sum));
    }
}

public static void main(String[] args) throws IOException {
    JobConf conf = new JobConf(WordCount.class);
    conf.setJobName("wordcount");

    conf.setOutputKeyClass(Text.class);
    conf.setOutputValueClass(IntWritable.class);

    conf.setMapperClass(Map.class);
    conf.setCombinerClass(Reduce.class);
    conf.setReducerClass(Reduce.class);

    conf.setInputFormat(TextInputFormat.class);
    conf.setOutputFormat(TextOutputFormat.class);

    FileInputFormat.setInputPaths(conf, new Path(args[0]));
    FileOutputFormat.setOutputPath(conf, new Path(args[1]));

    JobClient.runJob(conf);

}

}

[hue @ sandbox`] $ hadoop jar / usr / lib / wordcount.jar wordcount [-m] [ - r]

主线程java.lang.NoClassDefFoundError中的异常：jar / usr / lib / wordcount / jar

由引起的：java.lang.ClassNotFoundException：jar.usr.lib.wordcount.jar 在java.net.URLClassLoader $ 1.run（URLlassLoader.java:202） at java.security.AccessController.doPriviledged（Native Method）在java.net.URLClassLoader.findClass（URLClassLoader.java:190） at java.lang.ClassLoader.loadClass（ClassLoader.java:306） at sun.misc.Launcher $ AppClassLoader.loadClass（Laucher.java:301）在java.lang.ClassLoader.loadClass（ClassLoader.java:247）

找不到主类：jar / usr / lib / wordcount.jar

the exception tree is here

我在64位机器上使用Hortonworks + Sandbox + 1.3 + VirtualBox + RC6这个版本。

Answer 1

你没有正确调用hadoop，你错过了一个空格，还有args。尝试

hadoop jar /usr/lib/wordcount.jar WordCount <the path to your input file on HDFS> <the path to your output directory on HDFS>

如果找不到另一个类，请尝试使用WordCount的完整类名（例如，com.mysite.WordCount）。我看不出它的包装。

如何在Hortonworks沙箱Hadoop平台中运行mapreduce作业

1 个答案: