关于lucene自定义排序 FieldComparatorSource

其实关于FieldComparatorSource的lucene默认实现，应该已经满足我们对结果排序的需求了，比如：

如果我们希望对搜索结果按照一定的业务规则，人工干预排序，不妨尝试一下继承一下FieldComparatorSource以及实现FieldComparator类。
     以下是一个用户期望根据用户登录Ip对应的城市的相应数据排在最前面。
创建索引：

    /**
	 * 创建place索引
	 */
	public static void createPlaceIndex(){
		Analyzer  analyzer = new IKAnalyzer();
		PerFieldAnalyzerWrapper  perFieldAnalyzerWrapper = new PerFieldAnalyzerWrapper(analyzer);
		try {
			
			//perFieldAnalyzerWrapper.addAnalyzer("price", new WhitespaceAnalyzer());
			IndexWriter writer = new IndexWriter(FSDirectory.open(new File(index_path5)), perFieldAnalyzerWrapper, true,IndexWriter.MaxFieldLength.LIMITED);
			Document doc  = new Document();
			
			doc.add(new Field("placeName", "杭州西湖 测试开发", Field.Store.YES, Field.Index.ANALYZED));
			doc.add(new Field("placeName2", "杭州西湖 测试开发", Field.Store.YES, Field.Index.NOT_ANALYZED));
			writer.addDocument(doc);
			doc  = new Document();
			doc.add(new Field("placeName", "西湖 九天", Field.Store.YES, Field.Index.ANALYZED));
			doc.add(new Field("placeName2", "西湖 九天", Field.Store.YES, Field.Index.NOT_ANALYZED));
			writer.addDocument(doc);
			doc  = new Document();
			doc.add(new Field("placeName", "扬州廋西湖 高级开发", Field.Store.YES, Field.Index.ANALYZED));
			doc.add(new Field("placeName2", "扬州廋西湖 高级开发", Field.Store.YES, Field.Index.NOT_ANALYZED));
			writer.addDocument(doc);
			doc  = new Document();
			doc.add(new Field("placeName", "苏州西湖", Field.Store.YES, Field.Index.ANALYZED));
			doc.add(new Field("placeName2", "苏州西湖", Field.Store.YES, Field.Index.NOT_ANALYZED));
			writer.addDocument(doc);
			
		
			
			writer.close();
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}

实现Comparator以及ComparatorSource

     class PlaceNameSortComparatorSource  extends FieldComparatorSource {
	private String userLocation ;
	public PlaceNameSortComparatorSource(String userLocation ){
		this.userLocation = userLocation;
	}
	@Override
	public FieldComparator newComparator(String fieldname, int numHits,
			int sortPos, boolean reversed) throws IOException {
		// TODO Auto-generated method stub
		return new PlaceComparator(numHits,fieldname,userLocation);
	}
	
}


 final class PlaceComparator extends FieldComparator {
    private final String[] values;
    private String[] currentReaderValues;
    private final String field;
    private String bottom;
    private String userLocation;
    

    PlaceComparator(int numHits, String field, String userLocation) {
      values = new String[numHits];
      this.field = field;
      this.userLocation = userLocation;
    }

    @Override
    public int compare(int slot1, int slot2) {
    	
      int cmpValue=0;
      final String v1 = values[slot1];
      final String v2 = values[slot2];

      if(v1.indexOf(userLocation) !=-1){
    	  cmpValue= -999999999;
      }
      if(v2.indexOf(userLocation) !=-1){
    	  cmpValue= -999999999;
      }else{
    	  cmpValue = 999999999;
      }
      
      System.out.println(slot1+"-"+slot2);
      System.out.println(v1+"-"+v2);
      System.out.println("cmpValue="+cmpValue);
      return cmpValue;
    }

    @Override
    public int compareBottom(int doc) {
      final String v2 = currentReaderValues[doc];
      if(v2.indexOf(userLocation) !=-1){
    	  return -999999999;
      }
      if(bottom.indexOf(userLocation)!=-1){
    	  return -999999999;
      }
      return bottom.compareTo(v2);
    }

    @Override
    public void copy(int slot, int doc) {
      values[slot] = currentReaderValues[doc];
    }

    @Override
    public void setNextReader(IndexReader reader, int docBase) throws IOException {
      currentReaderValues = FieldCache.DEFAULT.getStrings(reader, field);
    }
    
    @Override
    public void setBottom(final int bottom) {
      this.bottom = values[bottom];
    }

    @Override
    public Comparable value(int slot) {
      return values[slot];
    }
    
  }

搜索测试：

    		Query trquery  = new PrefixQuery(new Term("placeName","西湖" ));   
		BooleanQuery booleanQuery = new BooleanQuery();
		TermQuery  tq  = new TermQuery(new Term("placeName","西湖"));

		IndexReader  indexReader = IndexReader.open(FSDirectory.open(new File(index_path5)));
		SortField sortField = new SortField("placeName2", new PlaceNameSortComparatorSource("扬州"),true );
		Sort sort = new Sort();     
		sort.setSort(sortField);
		
		Searcher  searcher = new IndexSearcher(indexReader);
		
		TopDocs topDocs = searcher.search(tq,null,100,sort);
		
		for (ScoreDoc hits:topDocs.scoreDocs){
			Document doc = searcher.doc(hits.doc);
			System.out.println("doc = "+doc.get("placeName"));
		}

运行结果：
doc = 扬州廋西湖 高级开发
doc = 西湖 九天
doc = 苏州西湖
doc = 杭州西湖 测试开发