lucene3.0学习笔记3-(IndexWriter的一些方法和属性)

2.3 Basic index operations
2.3.1 Adding documents to an index
IndexWriter有两个方法可以加入Document的方法

addDocument(Document)和addDocument(Document, Analyzer)

第一个是加Document使用默认的分词器，第二个是加入的时候使用指定的分词器

2.3.2 Deleting documents from an index
IndexWriter提供四个方法删除Document

deleteDocuments(Term);
deleteDocuments(Term[]);
deleteDocuments(Query);
deleteDocuments(Query[]);

一般最好有个唯一索引，这样才好删,不然的话有可以会一删一大堆
如：

writer.deleteDocument(new Term(“ID”, documentID));

package com.langhua;

import java.io.File;
import java.io.IOException;

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.Term;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.SimpleFSDirectory;
import org.apache.lucene.util.Version;
/**
 * Lucene 3.0+ 删除索引
 * @author Administrator
 *
 */

public class DeleteIndex {

	public static void main(String[] args) throws CorruptIndexException, IOException {
		//索引所放目录
		String indexDir = "F:\\indexDir";
		//创建Directory
		Directory dir =  new SimpleFSDirectory(new File(indexDir));		
		IndexWriter indexWriter = new IndexWriter(dir,new StandardAnalyzer(Version.LUCENE_30),false,IndexWriter.MaxFieldLength.UNLIMITED);
		//删除filename为time.txt的Document
		indexWriter.deleteDocuments(new Term("filename","time.txt"));
		//优化
		indexWriter.optimize();
		//提交事务
		indexWriter.commit();
		System.out.println("是否有删除="+indexWriter.hasDeletions());
		//如果不indexWriter.optimize()以下两个会有区别
		System.out.println("一共有"+indexWriter.maxDoc()+"索引");
		System.out.println("还剩"+indexWriter.numDocs()+"索引");
		indexWriter.close();
	}

}

2.3.3 Updating documents in the index
更新索引也提供两个方法，其实Lucene是没有办法更新的，只有先删除了再更新，方法如下

updateDocument(Term, Document) 
//first deletes all documents containing the provided term and then adds the new document using the writer’s default analyzer.
updateDocument(Term, Document, Analyzer) 
//does the same, but uses the provided analyzer instead of the writer’s default analyzer.

可以这样使用

writer.updateDocument(new Term(“ID”, documenteId), newDocument);

例子如下:

package com.langhua;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.Term;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.SimpleFSDirectory;
import org.apache.lucene.util.Version;

/**
 * Lucene 3.0 更新索引
 * 
 * @author Administrator
 * 
 */
public class updateIndex {
	public static void main(String[] args) throws IOException {
		String indexDir = "F:\\indexDir";
		String dateDir = "F:\\dateDir";
		Directory dir = new SimpleFSDirectory(new File(indexDir));
		IndexWriter indexWriter = new IndexWriter(dir, new StandardAnalyzer(
				Version.LUCENE_30), false, IndexWriter.MaxFieldLength.UNLIMITED);
		File[] files = new File(dateDir).listFiles();
		Document doc = new Document();
		for (int i = 0; i < files.length; i++) {
			if (files[i].getName().equals("time.txt")) {
				doc.add(new Field("contents", new FileReader(files[i])));
				doc.add(new Field("filename", files[i].getName(),
						Field.Store.YES, Field.Index.NOT_ANALYZED));
			}
		}
		// 更新索引使用默认分词器
		indexWriter.updateDocument(new Term("filename", "time.txt"), doc);
		indexWriter.close();
	}
}

2.4 Field options
2.4.1 Field options for indexing

在创建Field的时候一般常用的要指定两个参数
Field.Index.*
需要分词，并建立索引
Index.ANALYZED – use the analyzer to break the Field’s value into a stream of separate tokens
and make each token searchable. This is useful for normal text fields (body, title, abstract, etc.).

不分词，直接建立索引
Index.NOT_ANALYZED – do index the field, but do not analyze the String.

不用建立索引
Index.NO – don’t make this field’s value available for searching at all.

后面两个没有看懂。。
Index.ANALYZED_NO_NORMS
Index.NOT_ANALYZED_NO_NORMS

2.4.2 Field options for storing fields
要指定的另一个参数是:Field.Store.*

要保存在Document里面
Store.YES — store the value.

不要保存到Document里面,一般用于建立索引
Store.NO – do not store the value.

2.4.3 Field options for term vectors
在建立Field还有一个不常用的参数TermVector
http://callan.iteye.com/blog/155602参考一下
因为我也没有怎么看懂，书上说在后面有高亮作用。。。后面书上应该会介绍的

2.4.4 Other Field values
其它的创建Field方法

//uses a Reader instead of a String to represent the value. In this 
//case the value cannot be stored (hardwired to Store.NO)
//and is always analyzed and indexed (Index.ANALYZED).
//这个方法是用来分词的，不能保存
Field(String name, Reader value, TermVector vector)
//这个不懂
Field(String name, TokenStream tokenStream, TermVector TermVector)
//这个是图片的吧，只能保存，不能建立索引
//never indexed /no term vectors  /must be Store.YES
Field(String name, byte[] value, Store store)

2.4.5 Field option combinations
最后给出了一张图,说明在什么情况下用什么



2.5 Multi-valued Fields
创建多个值，例子:

Document doc = new Document();
for (int i = 0; i < authors.length; i++) {
    //多次加入同一个author
    doc.add(new Field("author", authors[i],
    Field.Store.YES,
    Field.Index.ANALYZED));
}

2.6 Boosting Documents and Fields
设置Boosting值，Boosting值在0.1到1.5之间，越大就越排在前面（或者是说越重要，就先搜到他），如果不设的话就没有
如:

Document doc = new Document();
doc..setBoost(0.1F); OR .setBoost(1.5);

Field senderNameField = new Field("senderName", senderName,
Field.Store.YES,
Field.Index.ANALYZED);
Field subjectField = new Field("subject", subject,
Field.Store.YES,
Field.Index.ANALYZED);
subjectField.setBoost(1.2F);

2.6.1 Norms
不明白，没看懂

2.7 Indexing dates & times
Lucene提供了一个工具类DateTools
可以这样来保存时间

Document doc = new Document();
doc.add(new Field("indexDate",
DateTools.dateToString(new Date(), DateTools.Resolution.DAY),
Field.Store.YES,
Field.Index.NOT_ANALYZED);

2.11 Optimizing an index
WriteIndex的优化索引方法

//优化索引，使多个Segments变成一个Segments
optimize()
//指定最大Segments的数量
optimize(int maxNumSegments)
//前面的方面都是优化完成之后再返回，这个方法的参数如果是FALSE的话，就直接返回，再开一个线程来优化
optimize(boolean doWait)
//前面两个参数的组合哈
optimize(int maxNumSegments, boolean doWait)

我对Segments还是不太明白，能不能有人出来解释一下啥

2.12 Other Directory Implementations
截了一张图



这一章后面基本上就晕了，完全不懂。。。