不推荐使用MapReduceBase和Mapper

Question

public static class Map extends MapReduceBase implements Mapper

MapReduceBase,Mapper并JobConf在Hadoop 0.20.203中弃用.

我们现在应该怎么用？

编辑1 - 对于Mapper和MapReduceBase,我发现我们只需要扩展Mapper

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, 
         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);
    }
  }
}

编辑2 - 因为JobConf我们应该使用这样的配置:

public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        Job job = new Job(conf);
        job.setMapperClass(WordCount.Map.class);
    }

编辑3 - 我根据新的API找到了一个很好的教程:http://sonerbalkir.blogspot.com/2010/01/new-hadoop-api-020x.html

Answer 1

Javadoc包含有关使用此depellyated类的instaed的信息:

例如http://hadoop.apache.org/common/docs/current/api/org/apache/hadoop/mapred/JobConf.html

 Deprecated. Use Configuration instead

编辑:当您使用Maven和开放类的声明(F3)Maven可以自动下载源代码,你会看到与解释javadoc注释的内容.