創建以下目錄:
GrouoingComparator.txt
0000001 Pdt_01 222.8
0000002 Pdt_05 722.4
0000001 Pdt_02 33.8
0000003 Pdt_06 232.8
0000003 Pdt_02 33.8
0000002 Pdt_03 522.8
0000002 Pdt_04 122.4
OrderBean.class
package com.atguigu.groupingcomparator;
import org.apache.hadoop.io.WritableComparable;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
public class OrderBean implements WritableComparable<OrderBean> {
private String orderId;
private String productId;
private double price;
@Override
public String toString() {
return orderId + "\t" + productId + "\t" + price;
}
public String getOrderId() {
return orderId;
}
public void setOrderId(String orderId) {
this.orderId = orderId;
}
public String getProductId() {
return productId;
}
public void setProductId(String productId) {
this.productId = productId;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
@Override
public int compareTo(OrderBean o) {
int compare = this.orderId.compareTo(o.orderId);
if (compare == 0){
return Double.compare(o.price, this.price);
}else{
return compare;
}
}
@Override
public void write(DataOutput out) throws IOException {
out.writeUTF(orderId);
out.writeUTF(productId);
out.writeDouble(price);
}
@Override
public void readFields(DataInput in) throws IOException {
this.orderId = in.readUTF();
this.productId = in.readUTF();
this.price = in.readDouble();
}
}
OrderComparator.class
package com.atguigu.groupingcomparator;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;
public class OrderComparator extends WritableComparator {
protected OrderComparator() {
super(OrderBean.class, true);
}
@Override
public int compare(WritableComparable a, WritableComparable b) {
OrderBean oa = (OrderBean) a;
OrderBean ob = (OrderBean) b;
return oa.getOrderId().compareTo(ob.getOrderId());
}
}
OrderDriver.class
package com.atguigu.groupingcomparator;
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;
import java.io.IOException;
public class OrderDriver {
public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
Job job = Job.getInstance(new Configuration());
job.setJarByClass(OrderDriver.class);
job.setMapperClass(OrderMapper.class);
job.setReducerClass(OrderReducer.class);
job.setMapOutputKeyClass(OrderBean.class);
job.setMapOutputValueClass(NullWritable.class);
job.setGroupingComparatorClass(OrderComparator.class);
job.setOutputKeyClass(OrderBean.class);
job.setOutputValueClass(NullWritable.class);
FileInputFormat.setInputPaths(job, new Path("d:\\input"));
FileOutputFormat.setOutputPath(job, new Path("d:\\output7"));
boolean b = job.waitForCompletion(true);
System.exit(b ? 0 : 1);
}
}
OrderMapper.class
package com.atguigu.groupingcomparator;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import java.io.IOException;
public class OrderMapper extends Mapper<LongWritable, Text, OrderBean, NullWritable> {
private OrderBean orderBean = new OrderBean();
@Override
protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
String[] fields = value.toString().split("\t");
orderBean.setOrderId(fields[0]);
orderBean.setProductId(fields[1]);
orderBean.setPrice(Double.parseDouble(fields[2]));
context.write(orderBean,NullWritable.get());
}
}
OrderReducer.class
package com.atguigu.groupingcomparator;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.Reducer;
import java.io.IOException;
public class OrderReducer extends Reducer<OrderBean, NullWritable, OrderBean, NullWritable> {
@Override
protected void reduce(OrderBean key, Iterable<NullWritable> values, Context context) throws IOException, InterruptedException {
context.write(key, NullWritable.get());
}
}