org.apache.lucene.document
Class Field

java.lang.Object
  extended byorg.apache.lucene.document.Field
All Implemented Interfaces:
Serializable

public final class Field
extends Object
implements Serializable

A field is a section of a Document. Each field has two parts, a name and a value. Values may be free text, provided as a String or as a Reader, or they may be atomic keywords, which are not further processed. Such keywords may be used to represent dates, urls, etc. Fields are optionally stored in the index, so that they may be returned with hits on the document.

See Also:
Serialized Form

Nested Class Summary
static class Field.Index
          Specifies whether and how a field should be indexed.
static class Field.Store
          Specifies whether and how a field should be stored.
static class Field.TermVector
          Specifies whether and how a field should have term vectors.
 
Constructor Summary
Field(String name, byte[] value, Field.Store store)
          Create a stored field with binary value.
Field(String name, Reader reader)
          Create a tokenized and indexed field that is not stored.
Field(String name, Reader reader, Field.TermVector termVector)
          Create a tokenized and indexed field that is not stored, optionally with storing term vectors.
Field(String name, String value, Field.Store store, Field.Index index)
          Create a field by specifying its name, value and how it will be saved in the index.
Field(String name, String value, Field.Store store, Field.Index index, Field.TermVector termVector)
          Create a field by specifying its name, value and how it will be saved in the index.
 
Method Summary
 byte[] binaryValue()
          The value of the field in Binary, or null.
 float getBoost()
          Returns the boost factor for hits for this field.
 boolean getOmitNorms()
          True if norms are omitted for this indexed field
 boolean isBinary()
          True iff the value of the filed is stored as binary
 boolean isCompressed()
          True if the value of the field is stored and compressed within the index
 boolean isIndexed()
          True iff the value of the field is to be indexed, so that it may be searched on.
 boolean isStored()
          True iff the value of the field is to be stored in the index for return with search hits.
 boolean isStoreOffsetWithTermVector()
          True iff terms are stored as term vector together with their offsets (start and end positon in source text).
 boolean isStorePositionWithTermVector()
          True iff terms are stored as term vector together with their token positions.
 boolean isTermVectorStored()
          True iff the term or terms used to index this field are stored as a term vector, available from IndexReader.getTermFreqVector(int,String).
 boolean isTokenized()
          True iff the value of the field should be tokenized as text prior to indexing.
 String name()
          Returns the name of the field as an interned string.
 Reader readerValue()
          The value of the field as a Reader, or null.
 void setBoost(float boost)
          Sets the boost factor hits on this field.
 void setOmitNorms(boolean omitNorms)
          Expert: If set, omit normalization factors associated with this indexed field.
 String stringValue()
          The value of the field as a String, or null.
 String toString()
          Prints a Field for human consumption.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

Field

public Field(String name,
             String value,
             Field.Store store,
             Field.Index index)
Create a field by specifying its name, value and how it will be saved in the index. Term vectors will not be stored in the index.

Parameters:
name - The name of the field
value - The string to process
store - Whether value should be stored in the index
index - Whether the field should be indexed, and if so, if it should be tokenized before indexing
Throws:
NullPointerException - if name or value is null
IllegalArgumentException - if the field is neither stored nor indexed

Field

public Field(String name,
             String value,
             Field.Store store,
             Field.Index index,
             Field.TermVector termVector)
Create a field by specifying its name, value and how it will be saved in the index.

Parameters:
name - The name of the field
value - The string to process
store - Whether value should be stored in the index
index - Whether the field should be indexed, and if so, if it should be tokenized before indexing
termVector - Whether term vector should be stored
Throws:
NullPointerException - if name or value is null
IllegalArgumentException - in any of the following situations:

Field

public Field(String name,
             Reader reader)
Create a tokenized and indexed field that is not stored. Term vectors will not be stored.

Parameters:
name - The name of the field
reader - The reader with the content
Throws:
NullPointerException - if name or reader is null

Field

public Field(String name,
             Reader reader,
             Field.TermVector termVector)
Create a tokenized and indexed field that is not stored, optionally with storing term vectors.

Parameters:
name - The name of the field
reader - The reader with the content
termVector - Whether term vector should be stored
Throws:
NullPointerException - if name or reader is null

Field

public Field(String name,
             byte[] value,
             Field.Store store)
Create a stored field with binary value. Optionally the value may be compressed.

Parameters:
name - The name of the field
value - The binary value
store - How value should be stored (compressed or not)
Throws:
IllegalArgumentException - if store is Store.NO
Method Detail

setBoost

public void setBoost(float boost)
Sets the boost factor hits on this field. This value will be multiplied into the score of all hits on this this field of this document.

The boost is multiplied by Document.getBoost() of the document containing this field. If a document has multiple fields with the same name, all such values are multiplied together. This product is then multipled by the value Similarity.lengthNorm(String,int), and rounded by Similarity.encodeNorm(float) before it is stored in the index. One should attempt to ensure that this product does not overflow the range of that encoding.

See Also:
Document.setBoost(float), Similarity.lengthNorm(String, int), Similarity.encodeNorm(float)

getBoost

public float getBoost()
Returns the boost factor for hits for this field.

The default value is 1.0.

Note: this value is not stored directly with the document in the index. Documents returned from IndexReader.document(int) and Hits.doc(int) may thus not have the same value present as when this field was indexed.

See Also:
setBoost(float)

name

public String name()
Returns the name of the field as an interned string. For example "date", "title", "body", ...


stringValue

public String stringValue()
The value of the field as a String, or null. If null, the Reader value or binary value is used. Exactly one of stringValue(), readerValue(), and binaryValue() must be set.


readerValue

public Reader readerValue()
The value of the field as a Reader, or null. If null, the String value or binary value is used. Exactly one of stringValue(), readerValue(), and binaryValue() must be set.


binaryValue

public byte[] binaryValue()
The value of the field in Binary, or null. If null, the Reader or String value is used. Exactly one of stringValue(), readerValue() and binaryValue() must be set.


isStored

public final boolean isStored()
True iff the value of the field is to be stored in the index for return with search hits. It is an error for this to be true if a field is Reader-valued.


isIndexed

public final boolean isIndexed()
True iff the value of the field is to be indexed, so that it may be searched on.


isTokenized

public final boolean isTokenized()
True iff the value of the field should be tokenized as text prior to indexing. Un-tokenized fields are indexed as a single word and may not be Reader-valued.


isCompressed

public final boolean isCompressed()
True if the value of the field is stored and compressed within the index


isTermVectorStored

public final boolean isTermVectorStored()
True iff the term or terms used to index this field are stored as a term vector, available from IndexReader.getTermFreqVector(int,String). These methods do not provide access to the original content of the field, only to terms used to index it. If the original content must be preserved, use the stored attribute instead.

See Also:
IndexReader.getTermFreqVector(int, String)

isStoreOffsetWithTermVector

public boolean isStoreOffsetWithTermVector()
True iff terms are stored as term vector together with their offsets (start and end positon in source text).


isStorePositionWithTermVector

public boolean isStorePositionWithTermVector()
True iff terms are stored as term vector together with their token positions.


isBinary

public final boolean isBinary()
True iff the value of the filed is stored as binary


getOmitNorms

public boolean getOmitNorms()
True if norms are omitted for this indexed field


setOmitNorms

public void setOmitNorms(boolean omitNorms)
Expert: If set, omit normalization factors associated with this indexed field. This effectively disables indexing boosts and length normalization for this field.


toString

public final String toString()
Prints a Field for human consumption.



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