Question

我正在用java开发一个Hadoop项目。我想在某一天找到最大消费的顾客。我已经设法在我想要的日期找到客户，但我在Reducer类中遇到了问题。这是代码：

Mapper类

<module name="com.fasterxml.jackson.module.jackson-module-jaxb-annotations"/>

减速机等级

import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.StringTokenizer;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class alicanteMapperC extends
        Mapper<LongWritable, Text, Text, IntWritable> {

    String Customer = new String();
    SimpleDateFormat ft = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    Date t = new Date();
    IntWritable Consumption = new IntWritable();
    int counter = 0;

    //new vars
    int max=0;

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

        Date d2 = null;
        try {
             d2 = ft.parse("2013-07-01 01:00:00");
        } catch (ParseException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        if (counter > 0) {

            String line = value.toString();
            StringTokenizer itr = new StringTokenizer(line, ",");

            while (itr.hasMoreTokens()) {
                Customer = itr.nextToken();
                try {
                    t = ft.parse(itr.nextToken());
                } catch (ParseException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                Consumption.set(Integer.parseInt(itr.nextToken()));
            }

            if (t.compareTo(d2) == 0) {
                context.write(new Text(Customer), Consumption);
            }
        }
        counter++;
    }
}

你知道为什么reducer不会写入输出文件吗？换句话说，为什么第二个不起作用？

修改在我的mapper类中，我在特定日期找到了Customers，因此消耗了它们，我在reducer类中传递了这些值。

在reducer类中，我想找到最大消耗量和与此消耗相关的客户。

Hadoop - java中的Reducer类

0 个答案: