MapReduce实战之辅助排序和二次排序案例

33.8

package com.atguigu.mapreduce.order;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.io.WritableComparable;
 
public class OrderBean implements WritableComparable<OrderBean> {
 
       private int order_id; // 订单id号
       private double price; // 价格
 
       public OrderBean() {
              super();
       }
 
       public OrderBean(int order_id, double price) {
              super();
              this.order_id = order_id;
              this.price = price;
       }
 
       @Override
       public void write(DataOutput out) throws IOException {
              out.writeInt(order_id);
              out.writeDouble(price);
       }
 
       @Override
       public void readFields(DataInput in) throws IOException {
              order_id = in.readInt();
              price = in.readDouble();
       }
 
       @Override
       public String toString() {
              return order_id + "\t" + price;
       }
 
       public int getOrder_id() {
              return order_id;
       }
 
       public void setOrder_id(int order_id) {
              this.order_id = order_id;
       }
 
       public double getPrice() {
              return price;
       }
 
       public void setPrice(double price) {
              this.price = price;
       }
 
       // 二次排序
       @Override
       public int compareTo(OrderBean o) {
 
              int result;
 
              if (order_id > o.getOrder_id()) {
                     result = 1;
              } else if (order_id < o.getOrder_id()) {
                     result = -1;
              } else {
                     // 价格倒序排序
                     result = price > o.getPrice() ? -1 : 1;
              }
 
              return result;
       }
}

package com.atguigu.mapreduce.order;
import java.io.IOException;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
 
public class OrderMapper extends Mapper<LongWritable, Text, OrderBean, NullWritable> {
       OrderBean k = new OrderBean();
      
       @Override
       protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
             
              // 1 获取一行
              String line = value.toString();
             
              // 2 截取
              String[] fields = line.split("\t");
             
              // 3 封装对象
              k.setOrder_id(Integer.parseInt(fields[0]));
              k.setPrice(Double.parseDouble(fields[2]));
             
              // 4 写出
              context.write(k, NullWritable.get());
       }
}

package com.atguigu.mapreduce.order;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.Partitioner;
 
publicclass OrderPartitioner extends Partitioner<OrderBean, NullWritable> {
 
       @Override
       publicint getPartition(OrderBean key, NullWritable value, int numReduceTasks) {
             
              return (key.getOrder_id() & Integer.MAX_VALUE) % numReduceTasks;
       }
}

package com.atguigu.mapreduce.order;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;
 
publicclass OrderGroupingComparator extends WritableComparator {
 
       protected OrderGroupingComparator() {
              super(OrderBean.class, true);
       }
 
       @SuppressWarnings("rawtypes")
       @Override
       publicint compare(WritableComparable a, WritableComparable b) {
 
              OrderBean aBean = (OrderBean) a;
              OrderBean bBean = (OrderBean) b;
 
              int result;
              if (aBean.getOrder_id() > bBean.getOrder_id()) {
                     result = 1;
              } elseif (aBean.getOrder_id() < bBean.getOrder_id()) {
                     result = -1;
              } else {
                     result = 0;
              }
 
              return result;
       }
}

package com.atguigu.mapreduce.order;
import java.io.IOException;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.Reducer;
 
publicclass OrderReducer extends Reducer<OrderBean, NullWritable, OrderBean, NullWritable> {
 
       @Override
       protectedvoid reduce(OrderBean key, Iterable<NullWritable> values, Context context)
                     throws IOException, InterruptedException {
             
              context.write(key, NullWritable.get());
       }
}

package com.atguigu.mapreduce.order;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
 
publicclass OrderDriver {
 
       publicstaticvoid main(String[] args) throws Exception, IOException {
 
              // 1 获取配置信息
              Configuration conf = new Configuration();
              Job job = Job.getInstance(conf);
 
              // 2 设置jar包加载路径
              job.setJarByClass(OrderDriver.class);
 
              // 3 加载map/reduce类
              job.setMapperClass(OrderMapper.class);
              job.setReducerClass(OrderReducer.class);
 
              // 4 设置map输出数据key和value类型
              job.setMapOutputKeyClass(OrderBean.class);
              job.setMapOutputValueClass(NullWritable.class);
 
              // 5 设置最终输出数据的key和value类型
              job.setOutputKeyClass(OrderBean.class);
              job.setOutputValueClass(NullWritable.class);
 
              // 6 设置输入数据和输出数据路径
              FileInputFormat.setInputPaths(job, new Path(args[0]));
              FileOutputFormat.setOutputPath(job, new Path(args[1]));
 
              // 10 设置reduce端的分组
              job.setGroupingComparatorClass(OrderGroupingComparator.class);
 
              // 7 设置分区
              job.setPartitionerClass(OrderPartitioner.class);
 
              // 8 设置reduce个数
              job.setNumReduceTasks(3);
 
              // 9 提交
              boolean result = job.waitForCompletion(true);
              System.exit(result ? 0 : 1);
       }
}