Merge pull request #2999 from dhruba619/master

BAEL-1160 Introduction to Apache Lucene

lucene/pom.xml

@@ -0,0 +1,37 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>com.baeldung</groupId>
+		<artifactId>parent-modules</artifactId>
+		<version>1.0.0-SNAPSHOT</version>
+	</parent>
+	<artifactId>lucene</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>lucene</name>
+	<description>An Apache Lucene demo application</description>
+
+	<dependencies>
+
+		<dependency>
+			<groupId>org.apache.lucene</groupId>
+			<artifactId>lucene-core</artifactId>
+			<version>7.1.0</version>
+		</dependency>
+
+		<dependency>
+			<groupId>org.apache.lucene</groupId>
+			<artifactId>lucene-queryparser</artifactId>
+			<version>7.1.0</version>
+		</dependency>
+		<!-- https://mvnrepository.com/artifact/junit/junit -->
+		<dependency>
+			<groupId>junit</groupId>
+			<artifactId>junit</artifactId>
+			<version>4.12</version>
+			<scope>test</scope>
+		</dependency>
+
+	</dependencies>
+
+</project>

lucene/src/main/java/com/baeldung/lucene/InMemoryLuceneIndex.java

@@ -0,0 +1,78 @@
+package com.baeldung.lucene;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.lucene.analysis.standard.StandardAnalyzer;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.TextField;
+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.queryparser.classic.ParseException;
+import org.apache.lucene.queryparser.classic.QueryParser;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.Query;
+import org.apache.lucene.search.ScoreDoc;
+import org.apache.lucene.search.TopDocs;
+import org.apache.lucene.store.Directory;
+
+public class InMemoryLuceneIndex {
+
+    private Directory memoryIndex;
+    private StandardAnalyzer analyzer;
+
+    public InMemoryLuceneIndex(Directory memoryIndex, StandardAnalyzer analyzer) {
+        super();
+        this.memoryIndex = memoryIndex;
+        this.analyzer = analyzer;
+    }
+
+    /**
+     * 
+     * @param title
+     * @param body
+     */
+    public void indexDocument(String title, String body) {
+
+        IndexWriterConfig indexWriterConfig = new IndexWriterConfig(analyzer);
+        try {
+            IndexWriter writter = new IndexWriter(memoryIndex, indexWriterConfig);
+            Document document = new Document();
+
+            document.add(new TextField("title", title, Field.Store.YES));
+            document.add(new TextField("body", body, Field.Store.YES));
+
+            writter.addDocument(document);
+            writter.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public List<Document> searchIndex(String inField, String queryString) {
+        try {
+            Query query = new QueryParser(inField, analyzer).parse(queryString);
+
+            IndexReader indexReader = DirectoryReader.open(memoryIndex);
+            IndexSearcher searcher = new IndexSearcher(indexReader);
+            TopDocs topDocs = searcher.search(query, 10);
+            List<Document> documents = new ArrayList<>();
+            for (ScoreDoc scoreDoc : topDocs.scoreDocs) {
+                documents.add(searcher.doc(scoreDoc.doc));
+            }
+
+            return documents;
+        } catch (IOException | ParseException e) {
+            e.printStackTrace();
+        }
+        return null;
+
+    }
+
+}
+
+

lucene/src/test/java/com/baeldung/lucene/LuceneInMemorySearchTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.lucene;
+
+import java.util.List;
+
+import org.apache.lucene.analysis.standard.StandardAnalyzer;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.store.RAMDirectory;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class LuceneInMemorySearchTest {
+
+    @Test
+    public void givenSearchQueryWhenFetchedDocumentThenCorrect() {
+        InMemoryLuceneIndex inMemoryLuceneIndex = new InMemoryLuceneIndex(new RAMDirectory(), new StandardAnalyzer());
+        inMemoryLuceneIndex.indexDocument("Hello world", "Some hello world ");
+
+        List<Document> documents = inMemoryLuceneIndex.searchIndex("body", "world");
+
+        Assert.assertEquals("Hello world", documents.get(0).get("title"));
+    }
+
+}

pom.xml

@@ -261,6 +261,7 @@
         <module>saas</module>
         <module>deeplearning4j</module>
         <module>spring-boot-admin</module>
+        <module>lucene</module>
     </modules>
 
     <dependencies>