我构建了一个查询，它本质上是其他查询的加权和：
val query = new BooleanQuery
for ((subQuery, weight) <- ...) {
subQuery.setBoost(weight)
query.add(subQuery, BooleanClause.Occur.MUST)
}
当我查询索引时，我会返回包含总分的文档。这很好，但我还需要知道每个子查询的子分数是多少。我怎样才能得到那些？这就是我现在正在做的事情：
for (scoreDoc <- searcher.search(query, nHits).scoreDocs) {
val score = scoreDoc.score
val subScores = subQueries.map { subQuery =>
val weight = searcher.createNormalizedWeight(subQuery)
val scorer = weight.scorer(reader, true, true)
scorer.advance(scoreDoc.doc)
scorer.score
}
}
我认为这给了我正确的分数，但是当我知道文档已经作为总分的一部分进行评分时，前进并重新评分似乎很浪费。
有没有更有效的方法来获得这些子分数？
[我的代码在 Scala 中，但如果更容易，请随时用 Java 响应。]
编辑：这是遵循罗伯特·缪尔的建议后的样子。
查询：
val query = new BooleanQuery
for ((subQuery, weight) <- ...) {
val weightedQuery = new BoostedQuery(subQuery, new ConstValueSource(weight))
query.add(weightedQuery, BooleanClause.Occur.MUST)
}
搜索：
val collector = new DocScoresCollector(nHits)
searcher.search(query, collector)
for (docScores <- collector.getDocSubScores) {
...
}
收藏者：
class DocScoresCollector(maxSize: Int) extends Collector {
var scorer: Scorer = null
var subScorers: Seq[Scorer] = null
val priorityQueue = new DocScoresPriorityQueue(maxSize)
override def setScorer(scorer: Scorer): Unit = {
this.scorer = scorer
// a little reflection hackery is required here because of a bug in
// BoostedQuery's scorer's getChildren method
// https://issues.apache.org/jira/browse/LUCENE-4261
this.subScorers = scorer.getChildren.asScala.map(childScorer =>
childScorer.child ...some hackery... ).toList
}
override def acceptsDocsOutOfOrder: Boolean = false
override def collect(doc: Int): Unit = {
this.scorer.advance(doc)
val score = this.scorer.score
val subScores = this.subScorers.map(_.score)
priorityQueue.insertWithOverflow(DocScores(doc, score, subScores))
}
override def setNextReader(context: AtomicReaderContext): Unit = {}
def getDocSubScores: Seq[DocScores] = {
val buffer = Buffer.empty[DocScores]
while (this.priorityQueue.size > 0) {
buffer += this.priorityQueue.pop
}
buffer
}
}
case class DocScores(doc: Int, score: Float, subScores: Seq[Float])
class DocScoresPriorityQueue(maxSize: Int) extends PriorityQueue[DocScores](maxSize) {
def lessThan(a: DocScores, b: DocScores) = a.score < b.score
}