需要實現以下幾個類,程式碼太多，列了下主要程式碼，可根據排重資料的特徵判讀是否需要新增combiner來提速。

public class GroupComparator implements RawComparator<MyBinaryKey> {
 
 @Override
 public int compare(MyBinaryKey o1, MyBinaryKey o2) {
  return o1.toString().compareTo(o2.toString());
 }

 @Override
 public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
  return WritableComparator.compareBytes(b1, s1, Long.SIZE / 8 + Integer.SIZE / 8 * 2, b2, s2,  Long.SIZE / 8 + Integer.SIZE / 8 * 2);
 }

}

public abstract class UVBinaryKey  extends BinaryComparable implements WritableComparable<BinaryComparable>{
 //根據需要新增屬性，get set方法
  @Override
 public void readFields(DataInput in) throws IOException {
        this.channelid = in.readLong();
        this.scope = in.readInt();
        this.type = in.readInt();
        int attrlen = in.readInt();
        attr = new byte[attrlen];
        in.readFully(attr);
        this.vv = in.readInt();
        this.vedioends = in.readInt();
        this.playtime = in.readInt();
} 

@Override
 public byte[] getBytes() {
      ByteArrayOutputStream buf = new ByteArrayOutputStream();
      DataOutput out = new DataOutputStream(buf);
      try {
             out.writeLong(this.channelid);
             out.writeInt(this.scope);
             out.writeInt(this.type);
             out.writeInt(this.attr.length);//需要新增比較屬性長度，避免比較時屬性長度不等且前面相同是匹配為相同
             out.write(this.attr);
             out.writeInt(this.vv);
             out.writeInt(this.vedioends);
             out.writeInt(this.playtime);
             return buf.toByteArray();
       } catch (IOException e) {
             e.printStackTrace();
       }
       return null;
}

}

public class MyPartitioner extends Partitioner<MyBinaryKey, NullWritable> {

 /**
  * 根據uv/ip取模分割槽，保證相同uv/ip落在同一分割槽
  */
 @Override
 public int getPartition(MyBinaryKey key, NullWritable value, int numPartitions) {
  
  int k=0;
  for(byte b : key.getAttr()){
   k+=b&0xff;
  }
  return k%numPartitions;
 }

}



  job.setMapOutputKeyClass(UVBinaryKey.class);
  job.setGroupingComparatorClass(GroupComparator.class);
   job.setPartitionerClass(MyPartitioner.class);

map略
 

combiner（根據需要新增）
reduce中的實現：
       @Override
        protected void reduce(UVBinaryKey key, Iterable<NullWritable> values, Context context)
                throws IOException,
                InterruptedException {
            long count = 0;
            byte[] tbsign = null;
            for (NullWritable nullWritable : values) {
                byte[] attr = key.getAttr();
                if (tbsign == null) {
                    tbsign = attr;
                    count++;
                }
                if (tbsign != null) {
                    if (tbsign.length != attr.length) {
                        count++;
                        tbsign = attr;
                    } else {
                        for (int i = 0; i < tbsign.length; i++) {
                            if (tbsign[i] != attr[i]) {
                                count++;
                                tbsign = attr;
                                break;
                            }
                        }
                    }
                }

            }
            StringBuffer out = new StringBuffer();
            out.append(new String(key.getChannelId()))
                    .append(Constants.FIELDS_TERMINATED).append(count);
            context.write(new Text(out.toString()), NullWritable.get());

        }