Lucene索引的【增、删、改、查】
前言
搞检索的，应该多少都会了解Lucene一些，它开源而且简单上手，官方API足够编写些小DEMO。并且根据倒排索引，实现快速检索。本文就简单的实现增量添加索引，删除索引，通过关键字查询，以及更新索引等操作。
目前博猪使用的不爽的地方就是，读取文件内容进行全文检索时，需要自己编写读取过程（这个solr免费帮我们实现）。而且创建索引的过程比较慢，还有很大的优化空间，这个就要细心下来研究了。
创建索引
Lucene在进行创建索引时，根据前面一篇博客，已经讲完了大体的流程，这里再简单说下：
1 Directory directory = FSDirectory.open("/tmp/testindex");
2 IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_CURRENT, analyzer);
3 IndexWriter iwriter = new IndexWriter(directory, config);
4 Document doc = new Document();
5 String text = "This is the text to be indexed.";
6 doc.add(new Field("fieldname", text, TextField.TYPE_STORED)); iwriter.close();
1 创建Directory，获取索引目录
2 创建词法分析器，创建IndexWriter对象
3 创建document对象，存储数据
4 关闭IndexWriter，提交
1 创建Directory，获取索引目录 2 创建词法分析器，创建IndexWriter对象 3 创建document对象，存储数据 4 关闭IndexWriter，提交
增量添加索引
Lucene拥有增量添加索引的功能，在不会影响之前的索引情况下，添加索引，它会在何时的时机，自动合并索引文件。
/**
* 增加索引
*
* @throws Exception
*/
public static void insert() throws Exception {
String text5 = "hello,goodbye,man,woman";
Date date1 = new Date();
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
directory = FSDirectory.open(new File(INDEX_DIR));
IndexWriterConfig config = new IndexWriterConfig(
Version.LUCENE_CURRENT, analyzer);
indexWriter = new IndexWriter(directory, config);
Document doc1 = new Document();
doc1.add(new TextField("filename", "text5", Store.YES));
doc1.add(new TextField("content", text5, Store.YES));
indexWriter.addDocument(doc1);
indexWriter.commit();
indexWriter.close();
Date date2 = new Date();
System.out.println("增加索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
}
删除索引
Lucene也是通过IndexWriter调用它的delete方法，来删除索引。我们可以通过关键字，删除与这个关键字有关的所有内容。如果仅仅是想要删除一个文档，那么最好就顶一个唯一的ID域，通过这个ID域，来进行删除操作。
/**
* 删除索引
*
* @param str 删除的关键字
* @throws Exception
*/
public static void delete(String str) throws Exception {
Date date1 = new Date();
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
directory = FSDirectory.open(new File(INDEX_DIR));
IndexWriterConfig config = new IndexWriterConfig(
Version.LUCENE_CURRENT, analyzer);
indexWriter = new IndexWriter(directory, config);
indexWriter.deleteDocuments(new Term("filename",str));
indexWriter.close();
Date date2 = new Date();
System.out.println("删除索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
}
更新索引
Lucene没有真正的更新操作，通过某个fieldname，可以更新这个域对应的索引，但是实质上，它是先删除索引，再重新建立的。
/**
* 更新索引
*
* @throws Exception
*/
public static void update() throws Exception {
String text1 = "update,hello,man!";
Date date1 = new Date();
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
directory = FSDirectory.open(new File(INDEX_DIR));
IndexWriterConfig config = new IndexWriterConfig(
Version.LUCENE_CURRENT, analyzer);
indexWriter = new IndexWriter(directory, config);
Document doc1 = new Document();
doc1.add(new TextField("filename", "text1", Store.YES));
doc1.add(new TextField("content", text1, Store.YES));
indexWriter.updateDocument(new Term("filename","text1"), doc1);
indexWriter.close();
Date date2 = new Date();
System.out.println("更新索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
}
通过索引查询关键字
Lucene的查询方式有很多种，这里就不做详细介绍了。它会返回一个ScoreDoc的集合，类似ResultSet的集合，我们可以通过域名获取想要获取的内容。
/**
* 关键字查询
*
* @param str
* @throws Exception
*/
public static void search(String str) throws Exception {
directory = FSDirectory.open(new File(INDEX_DIR));
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
DirectoryReader ireader = DirectoryReader.open(directory);
IndexSearcher isearcher = new IndexSearcher(ireader);
QueryParser parser = new QueryParser(Version.LUCENE_CURRENT, "content",analyzer);
Query query = parser.parse(str);
ScoreDoc[] hits = isearcher.search(query, null, 1000).scoreDocs;
for (int i = 0; i < hits.length; i++) {
Document hitDoc = isearcher.doc(hits[i].doc);
System.out.println(hitDoc.get("filename"));
System.out.println(hitDoc.get("content"));
}
ireader.close();
directory.close();
}
全部代码
package test;
import java.io.File;
import java.util.Date;
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.document.LongField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.document.Field.Store;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.Term;
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.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;
public class TestLucene {
// 保存路径
private static String INDEX_DIR = "D:\\luceneIndex";
private static Analyzer analyzer = null;
private static Directory directory = null;
private static IndexWriter indexWriter = null;
public static void main(String[] args) {
try {
// index();
search("man");
// insert();
// delete("text5");
// update();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 更新索引
*
* @throws Exception
*/
public static void update() throws Exception {
String text1 = "update,hello,man!";
Date date1 = new Date();
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
directory = FSDirectory.open(new File(INDEX_DIR));
IndexWriterConfig config = new IndexWriterConfig(
Version.LUCENE_CURRENT, analyzer);
indexWriter = new IndexWriter(directory, config);
Document doc1 = new Document();
doc1.add(new TextField("filename", "text1", Store.YES));
doc1.add(new TextField("content", text1, Store.YES));
indexWriter.updateDocument(new Term("filename","text1"), doc1);
indexWriter.close();
Date date2 = new Date();
System.out.println("更新索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
}
/**
* 删除索引
*
* @param str 删除的关键字
* @throws Exception
*/
public static void delete(String str) throws Exception {
Date date1 = new Date();
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
directory = FSDirectory.open(new File(INDEX_DIR));
IndexWriterConfig config = new IndexWriterConfig(
Version.LUCENE_CURRENT, analyzer);
indexWriter = new IndexWriter(directory, config);
indexWriter.deleteDocuments(new Term("filename",str));
indexWriter.close();
Date date2 = new Date();
System.out.println("删除索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
}
/**
* 增加索引
*
* @throws Exception
*/
public static void insert() throws Exception {
String text5 = "hello,goodbye,man,woman";
Date date1 = new Date();
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
directory = FSDirectory.open(new File(INDEX_DIR));
IndexWriterConfig config = new IndexWriterConfig(
Version.LUCENE_CURRENT, analyzer);
indexWriter = new IndexWriter(directory, config);
Document doc1 = new Document();
doc1.add(new TextField("filename", "text5", Store.YES));
doc1.add(new TextField("content", text5, Store.YES));
indexWriter.addDocument(doc1);
indexWriter.commit();
indexWriter.close();
Date date2 = new Date();
System.out.println("增加索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
}
/**
* 建立索引
*
* @param args
*/
public static void index() throws Exception {
String text1 = "hello,man!";
String text2 = "goodbye,man!";
String text3 = "hello,woman!";
String text4 = "goodbye,woman!";
Date date1 = new Date();
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
directory = FSDirectory.open(new File(INDEX_DIR));
IndexWriterConfig config = new IndexWriterConfig(
Version.LUCENE_CURRENT, analyzer);
indexWriter = new IndexWriter(directory, config);
Document doc1 = new Document();
doc1.add(new TextField("filename", "text1", Store.YES));
doc1.add(new TextField("content", text1, Store.YES));
indexWriter.addDocument(doc1);
Document doc2 = new Document();
doc2.add(new TextField("filename", "text2", Store.YES));
doc2.add(new TextField("content", text2, Store.YES));
indexWriter.addDocument(doc2);
Document doc3 = new Document();
doc3.add(new TextField("filename", "text3", Store.YES));
doc3.add(new TextField("content", text3, Store.YES));
indexWriter.addDocument(doc3);
Document doc4 = new Document();
doc4.add(new TextField("filename", "text4", Store.YES));
doc4.add(new TextField("content", text4, Store.YES));
indexWriter.addDocument(doc4);
indexWriter.commit();
indexWriter.close();
Date date2 = new Date();
System.out.println("创建索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
}
/**
* 关键字查询
*
* @param str
* @throws Exception
*/
public static void search(String str) throws Exception {
directory = FSDirectory.open(new File(INDEX_DIR));
analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
DirectoryReader ireader = DirectoryReader.open(directory);
IndexSearcher isearcher = new IndexSearcher(ireader);
QueryParser parser = new QueryParser(Version.LUCENE_CURRENT, "content",analyzer);
Query query = parser.parse(str);
ScoreDoc[] hits = isearcher.search(query, null, 1000).scoreDocs;
for (int i = 0; i < hits.length; i++) {
Document hitDoc = isearcher.doc(hits[i].doc);
System.out.println(hitDoc.get("filename"));
System.out.println(hitDoc.get("content"));
}
ireader.close();
directory.close();
}
}
