lucene util PriorityQueue 实现一优先队列

PriorityQueue  实现一优先队列框架，实例非常简单，只需实现lessThan(Object a, Object b)方法即可，通过该方法可以控制大优先或小优先。

 

package org.apache.lucene.search;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.util.PriorityQueue;

final class HitQueue extends PriorityQueue {
  HitQueue(int size) {
    initialize(size);
  }

  /**
   *
   * Annotator:yezheng
   */
  protected final boolean lessThan(Object a, Object b) {
    ScoreDoc hitA = (ScoreDoc)a;
    ScoreDoc hitB = (ScoreDoc)b;
    if (hitA.score == hitB.score)
      return hitA.doc > hitB.doc; // 如果分数相同则按索引先后顺序排序
    else
      return hitA.score < hitB.score;//否则,按score进行排序
  }
}