hadoop - Reducer在Hadoop Mapreduce中不起作用

嗨，我的 reducer 无法打印出理想的结果，请看一下代码。

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
01
01
01
02
01
02
01
03
01

reducer 后，我需要这样的输出
01
02
03

但是它正在打印所有东西
01
01
01
02
01
02
01
03
01

这是我的司机课

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);

最佳答案

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

关于hadoop - Reducer在Hadoop Mapreduce中不起作用，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/33516571/