lucene count奇怪的问题

//SpanNearQuery query

weight = query.createWeight(indexSearcher, false);

List<LeafReaderContext> leaves = indexSearcher.getIndexReader().leaves();

int count = 0;

Spans spans;

int docCount = 0;

for (LeafReaderContext leaf : leaves) {

    spans = weight.getSpans(leaf, SpanWeight.Postings.POSITIONS);

    while (spans != null && spans.nextDoc() != DocIdSetIterator.NO_MORE_DOCS) {

        while (spans.nextStartPosition() != spans.NO_MORE_POSITIONS) {

            count++;

        }

        docCount++;

    }

}

System.out.println("hits count = " + docCount);