Lucene In Action ch2 系统的讲解了 indexing,下面就来看看吧.
1,indexing的处理过程.
首先要把indexing的数据转换为text,因为Lucene只能索引text,然后由Analysis来过虑text,把一些ch1中提到的所谓的stop words 过滤掉, 然后建立index.建立的index为inverted index 也就是所谓的倒排索引.
2,基本的ingex操作
基本的操作 包括 :添加 删除 更新.
I . 添加
下面我们看个例子代码 BaseIndexingTestCase.class
01 package lia.indexing;
02
03 import org.apache.lucene.store.Directory;
04 import org.apache.lucene.store.FSDirectory;
05 import org.apache.lucene.document.Document;
06 import org.apache.lucene.document.Field;
07 import org.apache.lucene.index.IndexWriter;
08 import org.apache.lucene.index.IndexReader;
09 import org.apache.lucene.analysis.Analyzer;
10 import org.apache.lucene.analysis.SimpleAnalyzer;
11
12 import junit.framework.TestCase;
13 import java.io.IOException;
14
15 /**
16 *
17 */
18 public abstract class BaseIndexingTestCase extends TestCase {
19 protected String[] keywords = {"1", "2"};
20 protected String[] unindexed = {"Netherlands", "Italy"};
21 protected String[] unstored = {"Amsterdam has lots of bridges",
22 "Venice has lots of canals"};
23 protected String[] text = {"Amsterdam", "Venice"};
24 protected Directory dir;
25 // setUp 方法
26 protected void setUp() throws IOException {
27 String indexDir =
28 System.getProperty("java.io.tmpdir", "tmp") +
29 System.getProperty("file.separator") + "index-dir";
30 dir = FSDirectory.getDirectory(indexDir, true);
31 addDocuments(dir);
32 }
33
34 protected void addDocuments(Directory dir)
35 throws IOException {
36 IndexWriter writer = new IndexWriter(dir, getAnalyzer(),
37 true); // 得到indexWriter 实例
38 writer.setUseCompoundFile(isCompound());
39 for (int i = 0; i < keywords.length; i++) {
40 Document doc = new Document(); // 添加文档
41 doc.add(Field.Keyword("id", keywords[i]));
42 doc.add(Field.UnIndexed("country", unindexed[i]));
43 doc.add(Field.UnStored("contents", unstored[i]));
44 doc.add(Field.Text("city", text[i]));
45 writer.addDocument(doc);
46 }
47 writer.optimize(); // 优化index
48 writer.close();
49 }
50 // 可以覆盖该方法提供不同的Analyzer
51 protected Analyzer getAnalyzer() {
52 return new SimpleAnalyzer();
53 }
54 // 也可以覆盖该方法 指出Compound属性 是否是 Heterogeneous Documents
55 protected boolean isCompound() {
56 return true;
57 }
58 // 测试添加文档
59 public void testIndexWriter() throws IOException {
60 IndexWriter writer = new IndexWriter(dir, getAnalyzer(),
61 false);
62 assertEquals(keywords.length, writer.docCount());
63 writer.close();
64 }
65 // 测试IndexReader
66 public void testIndexReader() throws IOException {
67 IndexReader reader = IndexReader.open(dir);
68 assertEquals(keywords.length, reader.maxDoc());
69 assertEquals(keywords.length, reader.numDocs());
70 reader.close();
71 }
72 } |
这是一个测试超类 可以被其他的测试用例继承 来测试不同的功能.上面带有详细的注释.
在添加Field时, 会遇到同义词的情况,添加同义词由两种方式:
a.创建一个同义词词组,循环添加到Single Strng的不同Field中.
b.把同义词添加到一个Base word的field中.如下:
String baseWord = "fast";
String synonyms[] = String {"quick", "rapid", "speedy"};
Document doc = new Document();
doc.add(Field.Text("word", baseWord));
for (int i = 0; i < synonyms.length; i++) {
doc.add(Field.Text("word", synonyms[i]));
}
这样 在Lucene内部把每个词都添加的一个名为word的Field中,在搜索时 你可以使用任何一个给定的词语.