我正在尝试编写一个mapreduce场景，其中我以json的形式创建了一些用户clickstream数据。之后，我编写了mapper类来从文件中获取所需的数据，我的mapper代码是：-

private final static String URL = "u";

private final static String Country_Code = "c";

private final static String Known_User = "nk";

private final static String Session_Start_time = "hc";

private final static String User_Id = "user";

private final static String Event_Id = "event";

public void map(LongWritable key, Text value, Context context)
        throws IOException, InterruptedException {
    String aJSONRecord = value.toString();
    try {
        JSONObject aJSONObject = new JSONObject(aJSONRecord);
        StringBuilder aOutputString = new StringBuilder();
        aOutputString.append(aJSONObject.get(User_Id).toString()+",");
        aOutputString.append(aJSONObject.get(Event_Id).toString()+",");
        aOutputString.append(aJSONObject.get(URL).toString()+",");
        aOutputString.append(aJSONObject.get(Known_User)+",");
        aOutputString.append(aJSONObject.get(Session_Start_time)+",");
        aOutputString.append(aJSONObject.get(Country_Code)+",");
        context.write(new Text(aOutputString.toString()), key);
        System.out.println(aOutputString.toString());
    } catch (JSONException e) {
        e.printStackTrace();
    }
}

}
我的代码是：-

public void reduce(Text key, Iterable<LongWritable> values,
        Context context) throws IOException, InterruptedException {
        String aString =  key.toString();
        context.write(new Text(aString.trim()), new Text(""));  

}

我的分区代码是：-

public int getPartition(Text key, LongWritable value, int numPartitions) {
    String aRecord = key.toString();
    if(aRecord.contains(Country_code_Us)){
        return 0;
    }else{
        return 1;
    }
}

这是我的司机代码

public static void main(String[] args) throws Exception {
    Configuration conf = new Configuration();
    Job job = Job.getInstance(conf, "Click Stream Analyzer");
    job.setNumReduceTasks(2);
    job.setJarByClass(ClickStreamDriver.class);
    job.setMapperClass(ClickStreamMapper.class);
    job.setReducerClass(ClickStreamReducer.class);
    job.setPartitionerClass(ClickStreamPartitioner.class);
    job.setMapOutputKeyClass(Text.class);
    job.setMapOutputValueClass(LongWritable.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(Text.class);
    FileInputFormat.addInputPath(job, new Path(args[0]));
    FileOutputFormat.setOutputPath(job, new Path(args[1]));
    System.exit(job.waitForCompletion(true) ? 0 : 1);

}

在这里，我试图根据国家代码划分我的数据。但它不工作，它是在一个单一的reducer文件发送每一个记录，我想其他文件，然后为我们创建reduce。
还有一件事，当我看到Map器的输出时，它会在每条记录的末尾显示一些额外的空间。
如果我在这里犯了什么错误，请提出建议。