【手把手教你全文檢索】Lucene索引的【增、刪、改、查】

時間 2019-11-26

原文原文鏈接

前言html

　　搞檢索的，應該多少都會了解Lucene一些，它開源並且簡單上手，官方API足夠編寫些小DEMO。而且根據倒排索引，實現快速檢索。本文就簡單的實現增量添加索引，刪除索引，經過關鍵字查詢，以及更新索引等操做。java

　　目前博豬使用的不爽的地方就是，讀取文件內容進行全文檢索時，須要本身編寫讀取過程（這個solr免費幫咱們實現）。並且建立索引的過程比較慢，還有很大的優化空間，這個就要細心下來研究了。apache

　　建立索引

　　Lucene在進行建立索引時，根據前面一篇博客，已經講完了大致的流程，這裏再簡單說下：ide

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 建立Directory，獲取索引目錄優化

　　2 建立詞法分析器，建立IndexWriter對象spa

　　3 建立document對象，存儲數據code

　　4 關閉IndexWriter，提交htm

 1 /**
 2      * 創建索引
 3      * 
 4      * @param args
 5      */
 6     public static void index() throws Exception {
 7         
 8         String text1 = "hello,man!";
 9         String text2 = "goodbye,man!";
10         String text3 = "hello,woman!";
11         String text4 = "goodbye,woman!";
12         
13         Date date1 = new Date();
14         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
15         directory = FSDirectory.open(new File(INDEX_DIR));
16 
17         IndexWriterConfig config = new IndexWriterConfig(
18                 Version.LUCENE_CURRENT, analyzer);
19         indexWriter = new IndexWriter(directory, config);
20 
21         Document doc1 = new Document();
22         doc1.add(new TextField("filename", "text1", Store.YES));
23         doc1.add(new TextField("content", text1, Store.YES));
24         indexWriter.addDocument(doc1);
25         
26         Document doc2 = new Document();
27         doc2.add(new TextField("filename", "text2", Store.YES));
28         doc2.add(new TextField("content", text2, Store.YES));
29         indexWriter.addDocument(doc2);
30         
31         Document doc3 = new Document();
32         doc3.add(new TextField("filename", "text3", Store.YES));
33         doc3.add(new TextField("content", text3, Store.YES));
34         indexWriter.addDocument(doc3);
35         
36         Document doc4 = new Document();
37         doc4.add(new TextField("filename", "text4", Store.YES));
38         doc4.add(new TextField("content", text4, Store.YES));
39         indexWriter.addDocument(doc4);
40         
41         indexWriter.commit();
42         indexWriter.close();
43 
44         Date date2 = new Date();
45         System.out.println("建立索引耗時：" + (date2.getTime() - date1.getTime()) + "ms\n");
46     }

　　增量添加索引

　　Lucene擁有增量添加索引的功能，在不會影響以前的索引狀況下，添加索引，它會在什麼時候的時機，自動合併索引文件。對象

 1 /**
 2      * 增長索引
 3      * 
 4      * @throws Exception
 5      */
 6     public static void insert() throws Exception {
 7         String text5 = "hello,goodbye,man,woman";
 8         Date date1 = new Date();
 9         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
10         directory = FSDirectory.open(new File(INDEX_DIR));
11 
12         IndexWriterConfig config = new IndexWriterConfig(
13                 Version.LUCENE_CURRENT, analyzer);
14         indexWriter = new IndexWriter(directory, config);
15 
16         Document doc1 = new Document();
17         doc1.add(new TextField("filename", "text5", Store.YES));
18         doc1.add(new TextField("content", text5, Store.YES));
19         indexWriter.addDocument(doc1);
20 
21         indexWriter.commit();
22         indexWriter.close();
23 
24         Date date2 = new Date();
25         System.out.println("增長索引耗時：" + (date2.getTime() - date1.getTime()) + "ms\n");
26     }

　　刪除索引

　　Lucene也是經過IndexWriter調用它的delete方法，來刪除索引。咱們能夠經過關鍵字，刪除與這個關鍵字有關的全部內容。若是僅僅是想要刪除一個文檔，那麼最好就頂一個惟一的ID域，經過這個ID域，來進行刪除操做。blog

 1 /**
 2      * 刪除索引
 3      * 
 4      * @param str 刪除的關鍵字
 5      * @throws Exception
 6      */
 7     public static void delete(String str) throws Exception {
 8         Date date1 = new Date();
 9         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
10         directory = FSDirectory.open(new File(INDEX_DIR));
11 
12         IndexWriterConfig config = new IndexWriterConfig(
13                 Version.LUCENE_CURRENT, analyzer);
14         indexWriter = new IndexWriter(directory, config);
15         
16         indexWriter.deleteDocuments(new Term("filename",str));  
17         
18         indexWriter.close();
19         
20         Date date2 = new Date();
21         System.out.println("刪除索引耗時：" + (date2.getTime() - date1.getTime()) + "ms\n");
22     }

　　更新索引

　　Lucene沒有真正的更新操做，經過某個fieldname，能夠更新這個域對應的索引，可是實質上，它是先刪除索引，再從新創建的。

 1 /**
 2      * 更新索引
 3      * 
 4      * @throws Exception
 5      */
 6     public static void update() throws Exception {
 7         String text1 = "update,hello,man!";
 8         Date date1 = new Date();
 9          analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
10          directory = FSDirectory.open(new File(INDEX_DIR));
11 
12          IndexWriterConfig config = new IndexWriterConfig(
13                  Version.LUCENE_CURRENT, analyzer);
14          indexWriter = new IndexWriter(directory, config);
15          
16          Document doc1 = new Document();
17         doc1.add(new TextField("filename", "text1", Store.YES));
18         doc1.add(new TextField("content", text1, Store.YES));
19         
20         indexWriter.updateDocument(new Term("filename","text1"), doc1);
21         
22          indexWriter.close();
23          
24          Date date2 = new Date();
25          System.out.println("更新索引耗時：" + (date2.getTime() - date1.getTime()) + "ms\n");
26     }

　　經過索引查詢關鍵字

　　Lucene的查詢方式有不少種，這裏就不作詳細介紹了。它會返回一個ScoreDoc的集合，相似ResultSet的集合，咱們能夠經過域名獲取想要獲取的內容。

 1 /**
 2      * 關鍵字查詢
 3      * 
 4      * @param str
 5      * @throws Exception
 6      */
 7     public static void search(String str) throws Exception {
 8         directory = FSDirectory.open(new File(INDEX_DIR));
 9         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
10         DirectoryReader ireader = DirectoryReader.open(directory);
11         IndexSearcher isearcher = new IndexSearcher(ireader);
12 
13         QueryParser parser = new QueryParser(Version.LUCENE_CURRENT, "content",analyzer);
14         Query query = parser.parse(str);
15 
16         ScoreDoc[] hits = isearcher.search(query, null, 1000).scoreDocs;
17         for (int i = 0; i < hits.length; i++) {
18             Document hitDoc = isearcher.doc(hits[i].doc);
19             System.out.println(hitDoc.get("filename"));
20             System.out.println(hitDoc.get("content"));
21         }
22         ireader.close();
23         directory.close();
24     }

　　所有代碼

  1 package test;
  2 
  3 import java.io.File;
  4 import java.util.Date;
  5 import java.util.List;
  6 
  7 import org.apache.lucene.analysis.Analyzer;
  8 import org.apache.lucene.analysis.standard.StandardAnalyzer;
  9 import org.apache.lucene.document.Document;
 10 import org.apache.lucene.document.LongField;
 11 import org.apache.lucene.document.TextField;
 12 import org.apache.lucene.document.Field.Store;
 13 import org.apache.lucene.index.DirectoryReader;
 14 import org.apache.lucene.index.IndexWriter;
 15 import org.apache.lucene.index.IndexWriterConfig;
 16 import org.apache.lucene.index.Term;
 17 import org.apache.lucene.queryparser.classic.QueryParser;
 18 import org.apache.lucene.search.IndexSearcher;
 19 import org.apache.lucene.search.Query;
 20 import org.apache.lucene.search.ScoreDoc;
 21 import org.apache.lucene.store.Directory;
 22 import org.apache.lucene.store.FSDirectory;
 23 import org.apache.lucene.util.Version;
 24 
 25 public class TestLucene {
 26     // 保存路徑
 27     private static String INDEX_DIR = "D:\\luceneIndex";
 28     private static Analyzer analyzer = null;
 29     private static Directory directory = null;
 30     private static IndexWriter indexWriter = null;
 31 
 32     public static void main(String[] args) {
 33         try {
 34 //            index();
 35             search("man");
 36 //            insert();
 37 //            delete("text5");
 38 //            update();
 39         } catch (Exception e) {
 40             e.printStackTrace();
 41         }
 42     }
 43     /**
 44      * 更新索引
 45      * 
 46      * @throws Exception
 47      */
 48     public static void update() throws Exception {
 49         String text1 = "update,hello,man!";
 50         Date date1 = new Date();
 51          analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
 52          directory = FSDirectory.open(new File(INDEX_DIR));
 53 
 54          IndexWriterConfig config = new IndexWriterConfig(
 55                  Version.LUCENE_CURRENT, analyzer);
 56          indexWriter = new IndexWriter(directory, config);
 57          
 58          Document doc1 = new Document();
 59         doc1.add(new TextField("filename", "text1", Store.YES));
 60         doc1.add(new TextField("content", text1, Store.YES));
 61         
 62         indexWriter.updateDocument(new Term("filename","text1"), doc1);
 63         
 64          indexWriter.close();
 65          
 66          Date date2 = new Date();
 67          System.out.println("更新索引耗時：" + (date2.getTime() - date1.getTime()) + "ms\n");
 68     }
 69     /**
 70      * 刪除索引
 71      * 
 72      * @param str 刪除的關鍵字
 73      * @throws Exception
 74      */
 75     public static void delete(String str) throws Exception {
 76         Date date1 = new Date();
 77         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
 78         directory = FSDirectory.open(new File(INDEX_DIR));
 79 
 80         IndexWriterConfig config = new IndexWriterConfig(
 81                 Version.LUCENE_CURRENT, analyzer);
 82         indexWriter = new IndexWriter(directory, config);
 83         
 84         indexWriter.deleteDocuments(new Term("filename",str));  
 85         
 86         indexWriter.close();
 87         
 88         Date date2 = new Date();
 89         System.out.println("刪除索引耗時：" + (date2.getTime() - date1.getTime()) + "ms\n");
 90     }
 91     /**
 92      * 增長索引
 93      * 
 94      * @throws Exception
 95      */
 96     public static void insert() throws Exception {
 97         String text5 = "hello,goodbye,man,woman";
 98         Date date1 = new Date();
 99         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
100         directory = FSDirectory.open(new File(INDEX_DIR));
101 
102         IndexWriterConfig config = new IndexWriterConfig(
103                 Version.LUCENE_CURRENT, analyzer);
104         indexWriter = new IndexWriter(directory, config);
105 
106         Document doc1 = new Document();
107         doc1.add(new TextField("filename", "text5", Store.YES));
108         doc1.add(new TextField("content", text5, Store.YES));
109         indexWriter.addDocument(doc1);
110 
111         indexWriter.commit();
112         indexWriter.close();
113 
114         Date date2 = new Date();
115         System.out.println("增長索引耗時：" + (date2.getTime() - date1.getTime()) + "ms\n");
116     }
117     /**
118      * 創建索引
119      * 
120      * @param args
121      */
122     public static void index() throws Exception {
123         
124         String text1 = "hello,man!";
125         String text2 = "goodbye,man!";
126         String text3 = "hello,woman!";
127         String text4 = "goodbye,woman!";
128         
129         Date date1 = new Date();
130         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
131         directory = FSDirectory.open(new File(INDEX_DIR));
132 
133         IndexWriterConfig config = new IndexWriterConfig(
134                 Version.LUCENE_CURRENT, analyzer);
135         indexWriter = new IndexWriter(directory, config);
136 
137         Document doc1 = new Document();
138         doc1.add(new TextField("filename", "text1", Store.YES));
139         doc1.add(new TextField("content", text1, Store.YES));
140         indexWriter.addDocument(doc1);
141         
142         Document doc2 = new Document();
143         doc2.add(new TextField("filename", "text2", Store.YES));
144         doc2.add(new TextField("content", text2, Store.YES));
145         indexWriter.addDocument(doc2);
146         
147         Document doc3 = new Document();
148         doc3.add(new TextField("filename", "text3", Store.YES));
149         doc3.add(new TextField("content", text3, Store.YES));
150         indexWriter.addDocument(doc3);
151         
152         Document doc4 = new Document();
153         doc4.add(new TextField("filename", "text4", Store.YES));
154         doc4.add(new TextField("content", text4, Store.YES));
155         indexWriter.addDocument(doc4);
156         
157         indexWriter.commit();
158         indexWriter.close();
159 
160         Date date2 = new Date();
161         System.out.println("建立索引耗時：" + (date2.getTime() - date1.getTime()) + "ms\n");
162     }
163 
164     /**
165      * 關鍵字查詢
166      * 
167      * @param str
168      * @throws Exception
169      */
170     public static void search(String str) throws Exception {
171         directory = FSDirectory.open(new File(INDEX_DIR));
172         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
173         DirectoryReader ireader = DirectoryReader.open(directory);
174         IndexSearcher isearcher = new IndexSearcher(ireader);
175 
176         QueryParser parser = new QueryParser(Version.LUCENE_CURRENT, "content",analyzer);
177         Query query = parser.parse(str);
178 
179         ScoreDoc[] hits = isearcher.search(query, null, 1000).scoreDocs;
180         for (int i = 0; i < hits.length; i++) {
181             Document hitDoc = isearcher.doc(hits[i].doc);
182             System.out.println(hitDoc.get("filename"));
183             System.out.println(hitDoc.get("content"));
184         }
185         ireader.close();
186         directory.close();
187     }
188 }