lucene学习

发布时间：2023-09-06 02:04责任编辑：彭小芳关键词：暂无标签

一）回顾索引

定义：索引是对数据库表中一列或多列的值进行排序的一种结构

目的：加快对数据库表中记录的查询

特点：以空间换取时间，提高查询速度快

参见<<索引提高查询速度原理.JPG>>

二）体验百度搜索与原理图

参见<<在baidu中搜索Lucene关健字的结果.JPG>>

参见<<百度索搜宏观原理.JPG>>

参见<<百度索搜微观原理.JPG>>

三）什么是Lucene

Lucene是apache软件基金会发布的一个开放源代码的全文检索引擎工具包，由资深全文检索专家Doug Cutting所撰写,它是一个全文检索引擎的架构，提供了完整的创建索引和查询索引，以及部分文本分析的引擎，Lucene的目的是为软件开发人员提供一个简单易用的工具包，以方便在目标系统中实现全文检索的功能，或者是以此为基础建立起完整的全文检索引擎，Lucene在全文检索领域是一个经典的祖先，现在很多检索引擎都是在其基础上创建的，思想是相通的。

即：Lucene是根据关健字来搜索的文本搜索工具，只能在某个网站内部搜索文本内容，不能跨网站搜索

四） Lucene通常用在什么地方

Lucece不能用在互联网搜索（即像百度那样），只能用在网站内部的文本搜索（即只能在CRM，RAX，ERP内部使用），但思想是相通的。

参见<<Lucene用在什么地方.JPG>>

参见<<Lucene用在服务端三层结构中的哪一层.JPG>>

五） Lucene中存的什么内容

Lucene中存的就是一系列的二进制压缩文件和一些控制文件，它们位于计算机的硬盘上，

这些内容统称为索引库，索引库有二部份组成：

（1）原始记录

存入到索引库中的原始文本，例如：传智是一家IT培训机构

（2）词汇表

按照一定的拆分策略（即分词器）将原始记录中的每个字符拆开后，存入一个供将来搜索的表

参见<< Lucene索引库结构与原理图.JPG>>

六）为什么网站内部有些地方要用Lucene来索搜，而不全用SQL来搜索

（1）SQL只能针对数据库表搜索，不能直接针对硬盘上的文本搜索

（2）SQL没有相关度排名

（3）SQL搜索结果没有关健字高亮显示

（4）SQL需要数据库的支持，数据库本身需要内存开销较大，例如：Oracle

（5）SQL搜索有时较慢，尤其是数据库不在本地时，超慢，例如：Oracle

七）书写代码使用Lucene的流程图

参见<<Lucene程序宏观结构.JPG>>

参见<<Lucene索引库创建的过程.JPG>>

参见<<Lucene索引库查询的过程.JPG>>

创建索引库：

1）创建JavaBean对象

2）创建Docment对象

3）将JavaBean对象所有的属性值，均放到Document对象中去，属性名可以和JavaBean相同或不同

4）创建IndexWriter对象

5）将Document对象通过IndexWriter对象写入索引库中

6）关闭IndexWriter对象

根据关键字查询索引库中的内容：

1）创建IndexSearcher对象

2）创建QueryParser对象

3）创建Query对象来封装关键字

4）用IndexSearcher对象去索引库中查询符合条件的前100条记录，不足100条记录的以实际为准

5）获取符合条件的编号

6）用indexSearcher对象去索引库中查询编号对应的Document对象

7）将Document对象中的所有属性取出，再封装回JavaBean对象中去，并加入到集合中保存，以备将之用

八） Lucene快速入门

步一：创建javaweb工程，取名叫lucene-day01

步二：导入Lucene相关的jar包

lucene-core-3.0.2.jar【Lucene核心】

lucene-analyzers-3.0.2.jar【分词器】

lucene-highlighter-3.0.2.jar【Lucene会将搜索出来的字，高亮显示，提示用户】

lucene-memory-3.0.2.jar【索引库优化策略】

步三：创建包结构

cn.itcast.javaee.lucene.entity

cn.itcast.javaee.lucene.firstapp

cn.itcast.javaee.lucene.secondapp

cn.itcast.javaee.lucene.crud

cn.itcast.javaee.lucene.fy

cn.itcast.javaee.lucene.utils

。。。。。

步四：创建JavaBean类

public class Article {

private Integer id;//标题

private String title;//标题

private String content;//内容

public Article(){}

public Article(Integer id, String title, String content) {

this.id = id;

this.title = title;

this.content = content;

}

public Integer getId() {

return id;

}

public void setId(Integer id) {

this.id = id;

}

public String getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

public String getContent() {

return content;

}

public void setContent(String content) {

this.content = content;

}

步五：创建FirstLucene.java类，编写createIndexDB()和findIndexDB()二个业务方法

@Test

public void createIndexDB() throws Exception{

Article article = new Article(1,"培训","传智是一个Java培训机构");

Document document = new Document();

document.add(new Field("id",article.getId().toString(),Store.YES,Index.ANALYZED));

document.add(new Field("title",article.getTitle(),Store.YES,Index.ANALYZED));

document.add(new Field("content",article.getContent(),Store.YES,Index.ANALYZED));

Directory directory = FSDirectory.open(new File("E:/LuceneDBDBDBDBDBDBDBDBDB"));

Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_30);

MaxFieldLength maxFieldLength = MaxFieldLength.LIMITED;

IndexWriter indexWriter = new IndexWriter(directory,analyzer,maxFieldLength);

indexWriter.addDocument(document);

indexWriter.close();

}

@Test

public void findIndexDB() throws Exception{

List<Article> articleList = new ArrayList<Article>();

String keywords = "传";

Directory directory = FSDirectory.open(new File("E:/LuceneDBDBDBDBDBDBDBDBDB"));

Version version = Version.LUCENE_30;

Analyzer analyzer = new StandardAnalyzer(version);

QueryParser queryParser = new QueryParser(version,"content",analyzer);

Query query = queryParser.parse(keywords);

IndexSearcher indexSearcher = new IndexSearcher(directory);

TopDocs topDocs = indexSearcher.search(query,10);

for(int i=0;i<topDocs.scoreDocs.length;i++){

ScoreDoc scoreDoc = topDocs.scoreDocs[i];

int no = scoreDoc.doc;

Document document = indexSearcher.doc(no);

String id = document.get("id");

String title = document.get("title");

String content = document.get("content");

Article article = new Article(Integer.parseInt(id),title,content);

articleList.add(article);

}

for(Article article : articleList){

System.out.println(article.getId()+":"+article.getTitle()+":"+article.getContent());

}

九）创建LuceneUtil工具类，使用反射，封装通用的方法

public class LuceneUtil {

private static Directory directory ;

private static Analyzer analyzer ;

private static Version version;

private static MaxFieldLength maxFieldLength;

static{

try {

directory = FSDirectory.open(new File("E:/LuceneDBDBDBDBDBDBDBDBDB"));

version = Version.LUCENE_30;

analyzer = new StandardAnalyzer(version);

maxFieldLength = MaxFieldLength.LIMITED;

} catch (Exception e) {

throw new RuntimeException(e);

}

public static Directory getDirectory() {

return directory;

}

public static Analyzer getAnalyzer() {

return analyzer;

}

public static Version getVersion() {

return version;

}

public static MaxFieldLength getMaxFieldLength() {

return maxFieldLength;

}

public static Document javabean2documemt(Object obj) throws Exception{

Document document = new Document();

Class clazz = obj.getClass();

java.lang.reflect.Field[] reflectFields = clazz.getDeclaredFields();

for(java.lang.reflect.Field field : reflectFields){

field.setAccessible(true);

String fieldName = field.getName();

String init = fieldName.substring(0,1).toUpperCase();

String methodName = "get" + init + fieldName.substring(1);

Method method = clazz.getDeclaredMethod(methodName,null);

String returnValue = method.invoke(obj,null).toString();

document.add(new Field(fieldName,returnValue,Store.YES,Index.ANALYZED));

}

return document;

}

public static Object document2javabean(Document document,Class clazz) throws Exception{

Object obj = clazz.newInstance();

java.lang.reflect.Field[] reflectFields = clazz.getDeclaredFields();

for(java.lang.reflect.Field field : reflectFields){

field.setAccessible(true);

String fieldName = field.getName();

String fieldValue = document.get(fieldName);

BeanUtils.setProperty(obj,fieldName,fieldValue);

}

return obj;

}

十）使用LuceneUtil工具类，重构FirstLucene.java为SecondLucene.java

public class SecondLucene {

@Test

public void createIndexDB() throws Exception{

Article article = new Article(1,"Java培训","传智是一个Java培训机构");

Document document = LuceneUtil.javabean2documemt(article);

IndexWriter indexWriter = new IndexWriter(LuceneUtil.getDirectory(),LuceneUtil.getAnalyzer(),LuceneUtil.getMaxFieldLength());

indexWriter.addDocument(document);

indexWriter.close();

}

@Test

public void findIndexDB() throws Exception{

List<Article> articleList = new ArrayList<Article>();

String keywords = "传";

QueryParser queryParser = new QueryParser(LuceneUtil.getVersion(),"content",LuceneUtil.getAnalyzer());

Query query = queryParser.parse(keywords);

IndexSearcher indexSearcher = new IndexSearcher(LuceneUtil.getDirectory());

TopDocs topDocs = indexSearcher.search(query,10);

for(int i=0;i<topDocs.scoreDocs.length;i++){

ScoreDoc scoreDoc = topDocs.scoreDocs[i];

int no = scoreDoc.doc;

Document document = indexSearcher.doc(no);

Article article = (Article) LuceneUtil.document2javabean(document,Article.class);

articleList.add(article);

}

for(Article article : articleList){

System.out.println(article.getId()+":"+article.getTitle()+":"+article.getContent());

}

十一）使用LuceneUtil工具类，完成CURD操作

public class LuceneCURD {

@Test

public void addIndexDB() throws Exception{

Article article = new Article(1,"培训","传智是一个Java培训机构");

Document document = LuceneUtil.javabean2documemt(article);

IndexWriter indexWriter = new IndexWriter(LuceneUtil.getDirectory(),LuceneUtil.getAnalyzer(),LuceneUtil.getMaxFieldLength());

indexWriter.addDocument(document);

indexWriter.close();

}

@Test

public void updateIndexDB() throws Exception{

Integer id = 1;

Article article = new Article(1,"培训","广州传智是一个Java培训机构");

Document document = LuceneUtil.javabean2documemt(article);

Term term = new Term("id",id.toString());

IndexWriter indexWriter = new IndexWriter(LuceneUtil.getDirectory(),LuceneUtil.getAnalyzer(),LuceneUtil.getMaxFieldLength());

indexWriter.updateDocument(term,document);

indexWriter.close();

}

@Test

public void deleteIndexDB() throws Exception{

Integer id = 1;

Term term = new Term("id",id.toString());

IndexWriter indexWriter = new IndexWriter(LuceneUtil.getDirectory(),LuceneUtil.getAnalyzer(),LuceneUtil.getMaxFieldLength());

indexWriter.deleteDocuments(term);

indexWriter.close();

}

@Test

public void deleteAllIndexDB() throws Exception{

IndexWriter indexWriter = new IndexWriter(LuceneUtil.getDirectory(),LuceneUtil.getAnalyzer(),LuceneUtil.getMaxFieldLength());

indexWriter.deleteAll();

indexWriter.close();

}

@Test

public void searchIndexDB() throws Exception{

List<Article> articleList = new ArrayList<Article>();

String keywords = "传智";

QueryParser queryParser = new QueryParser(LuceneUtil.getVersion(),"content",LuceneUtil.getAnalyzer());

Query query = queryParser.parse(keywords);

IndexSearcher indexSearcher = new IndexSearcher(LuceneUtil.getDirectory());

TopDocs topDocs = indexSearcher.search(query,10);

for(int i = 0;i<topDocs.scoreDocs.length;i++){

ScoreDoc scoreDoc = topDocs.scoreDocs[i];

int no = scoreDoc.doc;

Document document = indexSearcher.doc(no);

Article article = (Article) LuceneUtil.document2javabean(document,Article.class);

articleList.add(article);

}

for(Article article : articleList){

System.out.println(article.getId()+":"+article.getTitle()+":"+article.getContent());

}

十二）使用Jsp +Js + Jquery + EasyUI + Servlet + Lucene，完成分页

步一：创建ArticleDao.java类

public class ArticleDao {

public Integer getAllObjectNum(String keywords) throws Exception{

QueryParser queryParser = new QueryParser(LuceneUtil.getVersion(),"content",LuceneUtil.getAnalyzer());

Query query = queryParser.parse(keywords);

IndexSearcher indexSearcher = new IndexSearcher(LuceneUtil.getDirectory());

TopDocs topDocs = indexSearcher.search(query,3);

return topDocs.totalHits;

}

public List<Article> findAllObjectWithFY(String keywords,Integer start,Integer size) throws Exception{

List<Article> articleList = new ArrayList<Article>();

QueryParser queryParser = new QueryParser(LuceneUtil.getVersion(),"content",LuceneUtil.getAnalyzer());

Query query = queryParser.parse(keywords);

IndexSearcher indexSearcher = new IndexSearcher(LuceneUtil.getDirectory());

TopDocs topDocs = indexSearcher.search(query,100000000);

int middle = Math.min(start+size,topDocs.totalHits);

for(int i=start;i<middle;i++){

ScoreDoc scoreDoc = topDocs.scoreDocs[i];

int no = scoreDoc.doc;

Document document = indexSearcher.doc(no);

Article article = (Article) LuceneUtil.document2javabean(document,Article.class);

articleList.add(article);

}

return articleList;

}

步二：创建PageBean.java类

public class PageBean {

private Integer allObjectNum;

private Integer allPageNum;

private Integer currPageNum;

private Integer perPageNum = 2;

private List<Article> articleList = new ArrayList<Article>();

public PageBean(){}

public Integer getAllObjectNum() {

return allObjectNum;

}

public void setAllObjectNum(Integer allObjectNum) {

this.allObjectNum = allObjectNum;

if(this.allObjectNum % this.perPageNum == 0){

this.allPageNum = this.allObjectNum / this.perPageNum;

}else{

this.allPageNum = this.allObjectNum / this.perPageNum + 1;

}

public Integer getAllPageNum() {

return allPageNum;

}

public void setAllPageNum(Integer allPageNum) {

this.allPageNum = allPageNum;

}

public Integer getCurrPageNum() {

return currPageNum;

}

public void setCurrPageNum(Integer currPageNum) {

this.currPageNum = currPageNum;

}

public Integer getPerPageNum() {

return perPageNum;

}

public void setPerPageNum(Integer perPageNum) {

this.perPageNum = perPageNum;

}

public List<Article> getArticleList() {

return articleList;

}

public void setArticleList(List<Article> articleList) {

this.articleList = articleList;

}

步三：创建ArticleService.java类

public class ArticleService {

private ArticleDao articleDao = new ArticleDao();

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