BinaryPartitioner.java 文件源码

/** 
 * Use (the specified slice of the array returned by) 
 * {@link BinaryComparable#getBytes()} to partition. 
 */
@Override
public int getPartition(BinaryComparable key, V value, int numPartitions) {
  int length = key.getLength();
  int leftIndex = (leftOffset + length) % length;
  int rightIndex = (rightOffset + length) % length;
  int hash = WritableComparator.hashBytes(key.getBytes(), 
    leftIndex, rightIndex - leftIndex + 1);
  return (hash & Integer.MAX_VALUE) % numPartitions;
}