MapReduceBase和Mapper已弃用 [英] MapReduceBase and Mapper deprecated

问题描述

  public static class Map extends MapReduceBase implements Mapper 
  

<在Hadoop中不推荐使用code> MapReduceBase ， Mapper 和 JobConf 0.20.203

。

我们现在应该使用什么？

编辑1 - code> Mapper 和 MapReduceBase ，我发现我们只需要扩展 Mapper
pre pre $ public static class Map扩展映射
< LongWritable，Text，Text，IntWritable> {
private static static IntWritable one = new IntWritable（1）;
私人文字=新文字（）;
$ b $ 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 - 对于 JobConf 我们应该使用如下配置：

  public static void main（String [ ] args）抛出异常{
 Configuration conf = new Configuration（）; 
工作职位=新职位（conf）; 
 job.setMapperClass（WordCount.Map.class）; 
} 
  

编辑3 - 根据新的API找到一个很好的教程： http://sonerbalkir.blogspot.com/2010/01/new-hadoop -api-020x.html

解决方案

Javadoc包含了如何使用这些depraceated类的instaed：

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

 已弃用。使用配置代替
  

编辑：当你使用maven和open类声明（F3）maven可以自动下载源码代码，您将看到javadoc注释的内容和解释。

public static class Map extends MapReduceBase implements Mapper

MapReduceBase, Mapper and JobConf are deprecated in Hadoop 0.20.203.

What should we use now?

Edit 1 - for the Mapper and the MapReduceBase, I found that we just need to extends the 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);
    }
  }
}

Edit 2 - For JobConf we should use configuration like this:

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

Edit 3 - I found a good tutorial according to the new API : http://sonerbalkir.blogspot.com/2010/01/new-hadoop-api-020x.html

解决方案

Javadoc contains info what to use instaed of this depraceated classes:

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

 Deprecated. Use Configuration instead

Edit: When you use maven and open class declaration (F3) maven can automatically download source code and you'll see content of javadoc comments with explanations.

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