org.apache.lucene.search.highlight

## Class QueryTermScorer

- java.lang.Object
- - org.apache.lucene.search.highlight.QueryTermScorer

All Implemented Interfaces:
  Scorer

    public class QueryTermScorer
    extends Object
    implements Scorer

`Scorer` implementation which scores text fragments by the number of unique query terms found. This class uses the `QueryTermExtractor` class to process determine the query terms and their boosts to be used.

### Constructor Summary

Constructors
Constructor and Description
`QueryTermScorer(Query query)`
`QueryTermScorer(Query query, IndexReader reader, String fieldName)`
`QueryTermScorer(Query query, String fieldName)`
`QueryTermScorer(WeightedTerm[] weightedTerms)`

### Method Summary

Methods
`void` `allFragmentsProcessed()`
`float` `getFragmentScore()` Called when the `Highlighter` has no more tokens for the current fragment - the Scorer returns the weighting it has derived for the most recent fragment, typically based on the results of `Scorer.getTokenScore()`.
`float` `getMaxTermWeight()`
`float` `getTokenScore()` Called for each token in the current fragment.
`TokenStream` `init(TokenStream tokenStream)` Called to init the Scorer with a `TokenStream`.
`void` `startFragment(TextFragment newFragment)` Called when a new fragment is started for consideration.

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

### Constructor Detail

#### QueryTermScorer

    public QueryTermScorer(Query query)

Parameters:
  `query` - a Lucene query (ideally rewritten using query.rewrite before being passed to this class and the searcher)

#### QueryTermScorer

    public QueryTermScorer(Query query,
                   String fieldName)

Parameters:
  `query` - a Lucene query (ideally rewritten using query.rewrite before being passed to this class and the searcher)
  `fieldName` - the Field name which is used to match Query terms

#### QueryTermScorer

    public QueryTermScorer(Query query,
                   IndexReader reader,
                   String fieldName)

Parameters:
  `query` - a Lucene query (ideally rewritten using query.rewrite before being passed to this class and the searcher)
  `reader` - used to compute IDF which can be used to a) score selected fragments better b) use graded highlights eg set font color intensity
  `fieldName` - the field on which Inverse Document Frequency (IDF) calculations are based

#### QueryTermScorer

    public QueryTermScorer(WeightedTerm[] weightedTerms)

### Method Detail

#### init

    public TokenStream init(TokenStream tokenStream)

Description copied from interface: `Scorer`
Called to init the Scorer with a `TokenStream`. You can grab references to the attributes you are interested in here and access them from `Scorer.getTokenScore()`.

Specified by:
  `init` in interface `Scorer`
Parameters:
  `tokenStream` - the `TokenStream` that will be scored.
Returns:
  either a `TokenStream` that the Highlighter should continue using (eg if you read the tokenSream in this method) or null to continue using the same `TokenStream` that was passed in.

#### startFragment

    public void startFragment(TextFragment newFragment)

Description copied from interface: `Scorer`
Called when a new fragment is started for consideration.

Specified by:
  `startFragment` in interface `Scorer`
Parameters:
  `newFragment` - the fragment that will be scored next

#### getTokenScore

    public float getTokenScore()

Description copied from interface: `Scorer`
Called for each token in the current fragment. The `Highlighter` will increment the `TokenStream` passed to init on every call.

Specified by:
  `getTokenScore` in interface `Scorer`
Returns:
  a score which is passed to the `Highlighter` class to influence the mark-up of the text (this return value is NOT used to score the fragment)

#### getFragmentScore

    public float getFragmentScore()

Description copied from interface: `Scorer`
Called when the `Highlighter` has no more tokens for the current fragment - the Scorer returns the weighting it has derived for the most recent fragment, typically based on the results of `Scorer.getTokenScore()`.

Specified by:
  `getFragmentScore` in interface `Scorer`

#### allFragmentsProcessed

    public void allFragmentsProcessed()

#### getMaxTermWeight

    public float getMaxTermWeight()

Returns:
  The highest weighted term (useful for passing to GradientFormatter to set top end of coloring scale.