GroupingSearch：setCaching(int maxDocsToCache, boolean cacheScores) 緩存
GroupingSearch：setCachingInMB(double maxCacheRAMMB, boolean cacheScores) 緩存第一次搜索結(jié)果，用于第二次搜索
GroupingSearch：setGroupDocsLimit(int groupDocsLimit) 指定每組返回的文檔數(shù)，不指定時，默認(rèn)返回一個文檔
GroupingSearch：setGroupSort(Sort groupSort) 指定分組排序

示例代碼：

1.先看建索引的代碼

public class IndexHelper {
  private Document document;
  private Directory directory;
  private IndexWriter indexWriter;
 
  public Directory getDirectory(){
    directory=(directory==null)? new RAMDirectory():directory;
    return directory;
  }
 
  private IndexWriterConfig getConfig() {
    return new IndexWriterConfig(Version.LUCENE_43, new IKAnalyzer(true));
  }
 
  private IndexWriter getIndexWriter() {
    try {
      return new IndexWriter(getDirectory(), getConfig());
    } catch (IOException e) {
      e.printStackTrace();
      return null;
    }
  }
 
  public IndexSearcher getIndexSearcher() throws IOException {
    return new IndexSearcher(DirectoryReader.open(getDirectory()));
  }
 
  /**
   * Create index for group test
   * @param author
   * @param content
   */
  public void createIndexForGroup(int id,String author,String content) {
    indexWriter = getIndexWriter();
    document = new Document();
    document.add(new IntField("id",id, Field.Store.YES));
    document.add(new StringField("author", author, Field.Store.YES));
    document.add(new TextField("content", content, Field.Store.YES));
    try {
      indexWriter.addDocument(document);
      indexWriter.commit();
      indexWriter.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

2.分組：

public class GroupTest

public void group(IndexSearcher indexSearcher,String groupField,String content) throws IOException, ParseException {
    GroupingSearch groupingSearch = new GroupingSearch(groupField);
    groupingSearch.setGroupSort(new Sort(SortField.FIELD_SCORE));
    groupingSearch.setFillSortFields(true);
    groupingSearch.setCachingInMB(4.0, true);
    groupingSearch.setAllGroups(true);
    //groupingSearch.setAllGroupHeads(true);
    groupingSearch.setGroupDocsLimit(10);
 
    QueryParser parser = new QueryParser(Version.LUCENE_43, "content", new IKAnalyzer(true));
    Query query = parser.parse(content);
 
    TopGroups<BytesRef> result = groupingSearch.search(indexSearcher, query, 0, 1000);
 
    System.out.println("搜索命中數(shù)：" + result.totalHitCount);
    System.out.println("搜索結(jié)果分組數(shù)：" + result.groups.length);
 
    Document document;
    for (GroupDocs<BytesRef> groupDocs : result.groups) {
      System.out.println("分組：" + groupDocs.groupValue.utf8ToString());
      System.out.println("組內(nèi)記錄：" + groupDocs.totalHits);
 
      //System.out.println("groupDocs.scoreDocs.length:" + groupDocs.scoreDocs.length);
      for (ScoreDoc scoreDoc : groupDocs.scoreDocs) {
        System.out.println(indexSearcher.doc(scoreDoc.doc));
      }
    }
  }

3.簡單的測試：

public static void main(String[] args) throws IOException, ParseException {
    IndexHelper indexHelper = new IndexHelper();
    indexHelper.createIndexForGroup(1,"紅薯", "開源中國");
    indexHelper.createIndexForGroup(2,"紅薯", "開源社區(qū)");
    indexHelper.createIndexForGroup(3,"紅薯", "代碼設(shè)計");
    indexHelper.createIndexForGroup(4,"紅薯", "設(shè)計");
    indexHelper.createIndexForGroup(5,"覺先", "Lucene開發(fā)");
    indexHelper.createIndexForGroup(6,"覺先", "Lucene實戰(zhàn)");
    indexHelper.createIndexForGroup(7,"覺先", "開源Lucene");
    indexHelper.createIndexForGroup(8,"覺先", "開源solr");
 
    indexHelper.createIndexForGroup(9,"散仙", "散仙開源Lucene");
    indexHelper.createIndexForGroup(10,"散仙", "散仙開源solr");
    indexHelper.createIndexForGroup(11,"散仙", "開源");
    GroupTest groupTest = new GroupTest();
 
    groupTest.group(indexHelper.getIndexSearcher(),"author", "開源");
  }
}

4.測試結(jié)果：

20163684827254.png (1168×355)

兩種分頁方式
Lucene有兩種分頁方式：

1、直接對搜索結(jié)果進(jìn)行分頁，數(shù)據(jù)量比較少的時候可以用這種方式，分頁代碼核心參照：

ScoreDoc[] sd = XXX;
// 查詢起始記錄位置
int begin = pageSize * (currentPage - 1);
// 查詢終止記錄位置
int end = Math.min(begin + pageSize, sd.length);
for (int i = begin; i < end && i <totalHits; i++) {
//對搜索結(jié)果數(shù)據(jù)進(jìn)行處理的代碼
}

2、使用searchAfter(...)

Lucene提供了五個重載方法，可以根據(jù)需要使用

20163684904821.png (1012×281)

ScoreDoc after：為上次搜索結(jié)果ScoreDoc總量減1；

Query query：查詢方式

int n：為每次查詢返回的結(jié)果數(shù)，即每頁的結(jié)果總量

一個簡單的使用示例：

//可以使用Map保存必要的搜索結(jié)果
Map<String, Object> resultMap = new HashMap<String, Object>();
ScoreDoc after = null;
Query query = XX
TopDocs td = search.searchAfter(after, query, size);
 
//獲取命中數(shù)
resultMap.put("num", td.totalHits);
 
ScoreDoc[] sd = td.scoreDocs;
for (ScoreDoc scoreDoc : sd) {
//經(jīng)典的搜索結(jié)果處理
}
//搜索結(jié)果ScoreDoc總量減1
after = sd[td.scoreDocs.length - 1]; 
//保存after用于下次搜索，即下一頁開始 
resultMap.put("after", after);
 
return resultMap;

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