Sometimes we may want to boost queries on specific fields. For example, I want to rank more to the documents that are written by the author ‘Ram’.
Example
Query authorBoostQuery = new BoostQuery(authorQuery, 3f);
Query authorBoostQuery = new BoostQuery(authorQuery, 3f);
Now, you can combine multiple queries using BooleanQuery like below.
BooleanQuery boolQuery = BooleanQuery.Builder.class.newInstance() .add(authorBoostQuery, BooleanClause.Occur.SHOULD).add(titleQuery, BooleanClause.Occur.SHOULD) .build();
Find the below working application.
DocumentUtil.java
package com.sample.app.util;
import java.util.Arrays;
import java.util.List;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.StringField;
import org.apache.lucene.document.TextField;
public class DocumentUtil {
public static Document getDocument(String id, String title, String description, String blog, List<String> authors) {
Document doc = new Document();
doc.add(new StringField("id", id, Field.Store.YES));
doc.add(new TextField("title", title, Field.Store.YES));
doc.add(new TextField("description", description, Field.Store.NO));
doc.add(new TextField("blog", blog, Field.Store.YES));
for (String author : authors) {
doc.add(new StringField("author", author, Field.Store.YES));
}
return doc;
}
public static List<Document> getDocuments() {
Document doc1 = getDocument("1", "Java World",
"The original independent resource for Java developers, architects, and managers.", " javaworld.com",
Arrays.asList("Ram"));
Document doc2 = getDocument("2", "Oracle Blogs | The Java Source",
" Java powers more than 4.5 billion devices including 800 million computers and 1.5 billion cell phones. If you love Java, this is the blog you must follow.",
"blogs.oracle.com/java", Arrays.asList("Ram"));
Document doc3 = getDocument("3", "A Java geek Professionals and experts",
"Nicolas Fränkel's blog. IT architect focusing on Java, Java EE, and their surrounding ecosystems. He is a trainer, book writer, speaker & blogger.",
"blog.frankel.ch", Arrays.asList("John"));
Document doc4 = getDocument("4", "Self Learning for Java Developers By Krishna (Java)", "Learn Java fundamentals and other java libraries",
"self-learning-java-tutorial.blogspot.com", Arrays.asList("Krishna"));
return Arrays.asList(doc1, doc2, doc3, doc4);
}
}
App.java
package com.sample.app;
import java.io.File;
import java.io.IOException;
import java.util.List;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.BooleanClause;
import org.apache.lucene.search.BooleanQuery;
import org.apache.lucene.search.BoostQuery;
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.MMapDirectory;
import org.apache.lucene.store.NoLockFactory;
import org.apache.lucene.util.QueryBuilder;
import com.sample.app.util.DocumentUtil;
public class App {
private static void printQueryResults(Query query, Directory directory) throws IOException {
try (IndexReader indexReader = DirectoryReader.open(directory)) {
IndexSearcher indexSearcher = new IndexSearcher(indexReader);
TopDocs docs = indexSearcher.search(query, 10);
ScoreDoc[] hits = docs.scoreDocs;
System.out.print("Total Hits: " + docs.totalHits);
System.out.print("Results: ");
for (int i = 0; i < hits.length; i++) {
Document d = indexSearcher.doc(hits[i].doc);
System.out.println("\nTitle: " + d.get("title"));
System.out.println("Score : " + hits[i].score);
IndexableField[] fields = d.getFields("author");
for (IndexableField field : fields) {
System.out.println("Author: " + field.stringValue());
}
System.out.println();
}
System.out.println("**************************************\n");
}
}
public static void main(String args[]) throws IOException, InstantiationException, IllegalAccessException {
Analyzer analyzer = new StandardAnalyzer();
IndexWriterConfig indexWriterConfig1 = new IndexWriterConfig(analyzer);
Directory directory = new MMapDirectory(new File("/Users/Shared/lucene").toPath(), NoLockFactory.INSTANCE);
try (IndexWriter indexWriter = new IndexWriter(directory, indexWriterConfig1)) {
List<Document> documents = DocumentUtil.getDocuments();
indexWriter.addDocuments(documents);
indexWriter.commit();
QueryBuilder queryBuilder = new QueryBuilder(analyzer);
Query authorQuery = new TermQuery(new Term("author", "Ram"));
Query titleQuery = queryBuilder.createPhraseQuery("title", "Java");
Query authorBoostQuery = new BoostQuery(authorQuery, 3f);
Query titleBoostQuery = new BoostQuery(titleQuery, 123.5f);
System.out.println("\nBoosting based on author");
BooleanQuery boolQuery = BooleanQuery.Builder.class.newInstance()
.add(authorBoostQuery, BooleanClause.Occur.SHOULD).add(titleQuery, BooleanClause.Occur.SHOULD)
.build();
printQueryResults(boolQuery, directory);
System.out.println("\nBoosting based on title");
boolQuery = BooleanQuery.Builder.class.newInstance().add(authorQuery, BooleanClause.Occur.SHOULD)
.add(titleBoostQuery, BooleanClause.Occur.SHOULD).build();
printQueryResults(boolQuery, directory);
}
}
}
Output
Boosting based on author Total Hits: 4 hitsResults: Title: Java World Score : 1.0093331 Author: Ram Title: Oracle Blogs | The Java Source Score : 0.9940433 Author: Ram Title: Self Learning for Java Developers By Krishna (Java) Score : 0.057394832 Author: Krishna Title: A Java geek Professionals and experts Score : 0.045246847 Author: John ************************************** Boosting based on title Total Hits: 4 hitsResults: Title: Java World Score : 8.23543 Author: Ram Title: Self Learning for Java Developers By Krishna (Java) Score : 7.088262 Author: Krishna Title: Oracle Blogs | The Java Source Score : 6.347131 Author: Ram Title: A Java geek Professionals and experts Score : 5.5879855 Author: John **************************************
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