hadoop - Reducer 在 Hadoop Mapreduce 中不工作

Question

您好，我的 Reducer 没有打印出想要的结果，请查看代码。

这是我的 map 功能

public  void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException 
        {   

            String str_line = value.toString();
            Detail_output1_column_array = str_line.split("\\"+tabSpace);


            Outputkey = Detail_output1_column_array[2];
            System.out.println(Outputkey);
            context.write(new Text(Outputkey),NullWritable.get());
        }
    }

    public  static class ShopFile_Reducer extends Reducer<Text,Iterable<NullWritable>,NullWritable,Text> {


        public void reduce(Text Key,Iterable<NullWritable> Values,Context context) throws IOException, InterruptedException {



            Key = new Text(Key.toString());
            context.write(NullWritable.get(),new Text(Key));

        }

    }

假设 Detail_output1_column_array[2] 包含010101020102010301

reducer 之后我需要这样的输出010203

但是它正在打印所有东西010101020102010301

这是我的驱动类

Configuration Shopconf = new Configuration();
        Shopconf.setStrings("DTGroup_input",DTGroup_input);
        Job Shop = new Job(Shopconf,"Export_Column_Mapping");
        Shop.setJarByClass(ExportColumnMapping.class);
        Shop.setJobName("ShopFile_Job");
        Shop.setMapperClass(ShopFile_Mapper.class);
        Shop.setReducerClass(ShopFile_Reducer.class);
        Shop.setInputFormatClass(TextInputFormat.class);
        Shop.setOutputFormatClass(TextOutputFormat.class);
        Shop.setMapOutputKeyClass(Text.class);
        Shop.setMapOutputValueClass(NullWritable.class);
        Shop.setOutputKeyClass(Text.class);
        Shop.setOutputValueClass(Text.class);
        FileInputFormat.addInputPath(Shop, new Path(outputpath+"/Detailsfile/part*"));
        FileOutputFormat.setOutputPath(Shop, new Path(outputpath+"/Shopfile"));
        Shop.waitForCompletion(true);

Answer 1

在您的映射器代码中使用此 Outputkey.set( Detail_output1_column_array[2]); 而不是 Outputkey = Detail_output1_column_array[2];