我已经在一个节点上测试了一个map reduce作业，它似乎可以工作，但是现在我正在尝试在一个远程集群上运行它，我得到了一个classnotfoundexcepton。我的代码结构如下：

public class Pivot {
    public static class Mapper extends TableMapper<ImmutableBytesWritable, ImmutableBytesWritable> {
        @Override
        public void map(ImmutableBytesWritable rowkey, Result values, Context context) throws IOException {
            (map code)
        }
    }

    public static class Reducer extends TableReducer<ImmutableBytesWritable, ImmutableBytesWritable, ImmutableBytesWritable> {
        public void reduce(ImmutableBytesWritable key, Iterable<ImmutableBytesWritable> values, Context context) throws IOException, InterruptedException {
            (reduce code)
        }
    }

    public static void main(String[] args) {
        Configuration conf = HBaseConfiguration.create();
        conf.set("fs.default.name", "hdfs://hadoop-master:9000");
        conf.set("mapred.job.tracker", "hdfs://hadoop-master:9001");
        conf.set("hbase.master", "hadoop-master:60000");
        conf.set("hbase.zookeeper.quorum", "hadoop-master");
        conf.set("hbase.zookeeper.property.clientPort", "2222");
        Job job = new Job(conf);
        job.setJobName("Pivot");
        job.setJarByClass(Pivot.class);
        Scan scan = new Scan();
        TableMapReduceUtil.initTableMapperJob("InputTable", scan, Mapper.class, ImmutableBytesWritable.class, ImmutableBytesWritable.class, job);
        TableMapReduceUtil.initTableReducerJob("OutputTable", Reducer.class, job);
        job.waitForCompletion(true);
    }
}

尝试运行此作业时收到的错误如下：

java.lang.RuntimeException: java.lang.ClassNotFoundException: Pivot$Mapper
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:857)
    ...

有什么我不知道的吗？为什么工作很难找到Map绘制者？