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并不是所有的Document和Field是平等创建的。Document增量是个使得这种需求能够简单实现的一个特征。默认情况下,所有的 Document都没有增量,他们都有相同的增量因数1.0。通过改变某个Document的增量因数,可以让Lucene认为它比索引中的其他 Document更重要或更不重要。在索引的时候只需执行setBoost(float)方法。
看两个示例,就能明白其中的用法。
示例1,使用默认的的boost
- package com.cn;
- import org.apache.lucene.analysis.standard.StandardAnalyzer;
- import org.apache.lucene.document.Document;
- import org.apache.lucene.document.Field;
- import org.apache.lucene.index.IndexWriter;
- import org.apache.lucene.index.IndexWriterConfig;
- import org.apache.lucene.index.Term;
- import org.apache.lucene.search.IndexSearcher;
- import org.apache.lucene.search.Query;
- import org.apache.lucene.search.ScoreDoc;
- import org.apache.lucene.search.TermQuery;
- import org.apache.lucene.search.TopDocs;
- import org.apache.lucene.store.Directory;
- import org.apache.lucene.store.RAMDirectory;
- import org.apache.lucene.util.Version;
- public class TT {
- public static void main(String []args) throws Exception {
- String [] ids = {“1″,”2″,”3″,”4″,”5″};
- String [] province = {“shanghai”,”beijing”,”liaoning”,”liaoning”,”zhejiang”};
- String [] contents = {“shanghai is a city”,”beijing is a city”,”jinzhou is a city”,”shenyang is a city”,”hangzhou is a city”};
- String [] city = {“shanghai”,”beijing”,”jinzhou”,”shenyang”,”hangzhou”};
- Directory directory = new RAMDirectory();
- IndexWriter indexWriter = new IndexWriter(directory,new IndexWriterConfig(Version.LUCENE_34, new StandardAnalyzer(Version.LUCENE_34)));
- for(int i = 0;i < ids.length;i++){
- Document doc = new Document();
- doc.add(new Field(“id”,ids[i],Field.Store.YES,Field.Index.NOT_ANALYZED));
- doc.add(new Field(“province”,province[i],Field.Store.YES,Field.Index.ANALYZED));
- doc.add(new Field(“contents”,contents[i],Field.Store.YES,Field.Index.ANALYZED));
- doc.add(new Field(“city”,city[i],Field.Store.YES,Field.Index.ANALYZED));
- indexWriter.addDocument(doc);
- }
- System.out.println(“total:”+indexWriter.numDocs());
- indexWriter.close();
- queryMethod(directory,”contents”,”city”);
- }
- public static void queryMethod(Directory directory,String item,String txt)throws Exception {
- Term term = new Term(item,txt);
- Query query = new TermQuery(term);
- IndexSearcher indexSearcher = new IndexSearcher(directory);
- TopDocs topDocs = indexSearcher.search(query, 10);
- System.out.println(“it has “+topDocs.totalHits+” “+txt+” in “+item);
- ScoreDoc [] scoreDoc = topDocs.scoreDocs;
- for(int i=0;i<scoreDoc.length;i++){
- Document d = indexSearcher.doc(scoreDoc[i].doc);
- System.out.println(“city:”+d.get(“city”));
- System.out.println(“contents:”+d.get(“contents”));
- }
- }
- }
运行结果为:
total:5
it has 5 city in contents
province:shanghai city:shanghai
contents:shanghai is a city
province:beijing city:beijing
contents:beijing is a city
province:liaoning city:jinzhou
contents:jinzhou is a city
province:liaoning city:shenyang
contents:shenyang is a city
province:zhejiang city:hangzhou
contents:hangzhou is a city
示例2,增加了boost,代码为
- package com.cn;
- import org.apache.lucene.analysis.standard.StandardAnalyzer;
- import org.apache.lucene.document.Document;
- import org.apache.lucene.document.Field;
- import org.apache.lucene.index.IndexWriter;
- import org.apache.lucene.index.IndexWriterConfig;
- import org.apache.lucene.index.Term;
- import org.apache.lucene.search.IndexSearcher;
- import org.apache.lucene.search.Query;
- import org.apache.lucene.search.ScoreDoc;
- import org.apache.lucene.search.TermQuery;
- import org.apache.lucene.search.TopDocs;
- import org.apache.lucene.store.Directory;
- import org.apache.lucene.store.RAMDirectory;
- import org.apache.lucene.util.Version;
- public class TT {
- public static void main(String []args) throws Exception {
- String [] ids = {“1″,”2″,”3″,”4″,”5″};
- String [] province = {“shanghai”,”beijing”,”liaoning”,”liaoning”,”zhejiang”};
- String [] contents = {“shanghai is a city”,”beijing is a city”,”jinzhou is a city”,”shenyang is a city”,”hangzhou is a city”};
- String [] city = {“shanghai”,”beijing”,”jinzhou”,”shenyang”,”hangzhou”};
- Directory directory = new RAMDirectory();
- IndexWriter indexWriter = new IndexWriter(directory,new IndexWriterConfig(Version.LUCENE_34, new StandardAnalyzer(Version.LUCENE_34)));
- for(int i = 0;i < ids.length;i++){
- Document doc = new Document();
- doc.add(new Field(“id”,ids[i],Field.Store.YES,Field.Index.NOT_ANALYZED));
- doc.add(new Field(“province”,province[i],Field.Store.YES,Field.Index.ANALYZED));
- doc.add(new Field(“contents”,contents[i],Field.Store.YES,Field.Index.ANALYZED));
- doc.add(new Field(“city”,city[i],Field.Store.YES,Field.Index.ANALYZED));
- if(province[i].equals(“liaoning”)){
- if(city[i].equals(“shenyang”)){
- doc.setBoost(5.0f);
- }else{
- doc.setBoost(2.0f);
- }
- }
- indexWriter.addDocument(doc);
- }
- System.out.println(“total:”+indexWriter.numDocs());
- indexWriter.close();
- queryMethod(directory,”contents”,”city”);
- }
- public static void queryMethod(Directory directory,String item,String txt)throws Exception {
- Term term = new Term(item,txt);
- Query query = new TermQuery(term);
- IndexSearcher indexSearcher = new IndexSearcher(directory);
- TopDocs topDocs = indexSearcher.search(query, 10);
- System.out.println(“it has “+topDocs.totalHits+” “+txt+” in “+item);
- ScoreDoc [] scoreDoc = topDocs.scoreDocs;
- for(int i=0;i<scoreDoc.length;i++){
- Document d = indexSearcher.doc(scoreDoc[i].doc);
- System.out.println(“city:”+d.get(“city”));
- System.out.println(“contents:”+d.get(“contents”));
- }
- }
- }
运行结果为: total:5
it has 5 city in contents
city:shenyang
contents:shenyang is a city
city:jinzhou
contents:jinzhou is a city
city:shanghai
contents:shanghai is a city
city:beijing
contents:beijing is a city
city:hangzhou
contents:hangzhou is a city
从两个例子中看出属于辽宁省的结果在靠前位置了,而且shenyang比jinzhou还要靠前。