hadoop在eclipse当中如何添加源码？

最新推荐文章于 2020-05-12 22:07:43 发布

原创最新推荐文章于 2020-05-12 22:07:43 发布 · 287 阅读

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#Hadoop #马克-to-win #马克java社区 #hadoop eclipse如何添加源码

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博客介绍了在Hadoop中查看map源代码的方法，通过按control点击出现Attach Source Code，选择External Location/External File找到Source目录下的源代码。还给出了WordCount的代码示例，包含map和reduce方法，以及main函数的配置。

/*org.apache.hadoop.mapreduce.Mapper.Context,java.lang.InterruptedException,想看map的源代码，按control，点击，出现Attach Source Code,点击External Location/External File,找到源代码，就在Source目录下，,D:\hadoop-2.7.4\src
其中key为此行的开头相对于文件的起始位置，value就是此行的字符文本
*/ public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            System.out.println("key is 马克-to-win @ 马克java社区 "+key.toString()+" value is "+value.toString());
            StringTokenizer itr = new StringTokenizer(value.toString());
            while (itr.hasMoreTokens()) {
                word.set(itr.nextToken());
                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 {
            System.out.println("reduce key is 马克-to-win @ 马克java社区 "+key.toString());
            int sum = 0;
            for (IntWritable val : values) {
                int valValue=val.get();
                System.out.println("valValue is"+valValue);
                sum += valValue ;
            }
            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> <out>");
            System.exit(2);
        }
        Job job = new Job(conf, "word count");
        job.setJarByClass(WordCount.class);
        job.setMapperClass(TokenizerMapper.class);