Nutch索引
NutchField

package org.apache.nutch.indexer;class NutchField implements Writable {    float weight;    List values;}

Metadata

package org.apache.nutch.metadataclass Metadata {    Map metadata;}

NutchDocument

package org.apache.nutch.indexer;class NutchDocument {    byte Version = 2;    Map fields;    Metadata documentMeta;    float weight;}

Nutch建立索引的过程中，将会把NutchDocument转换为Lucene的Document对象进行索引。