使用Lucene實現全文檢索,主要有下面三個步驟:
1、建立索引庫:根據網站新聞信息庫中的已有的數據資料建立Lucene索引文件。
2、通過索引庫搜索:有了索引后,即可使用標準的詞法分析器或直接的詞法分析器實現進行全文檢索。
3、維護索引庫:網站新聞信息庫中的信息會不斷的變動,包括新增、修改及刪除等,這些信息的變動都需要進一步反映到Lucene索引文件中。
下面是myrss.easyjf.com相關代碼!
一、索引管理(建立及維護)
索引管理類MyRssIndexManage主要實現根據網站信息庫中的數據建立索引,維護索引等。由于索引的過程需要消耗一定的時間,因此,索引管理類實現Runnable接口,使得我們可以在程序中開新線程來運行。
package com.easyjf.lucene;
import java.util.Date;
import java.util.List;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.queryParser.MultiFieldQueryParser;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.Hits;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Searcher;
import com.easyjf.dbo.EasyJDB;
import com.easyjf.news.business.NewsDir;
import com.easyjf.news.business.NewsDoc;
import com.easyjf.news.business.NewsUtil;
import com.easyjf.web.tools.IPageList;
 public class MyRssIndexManage implements Runnable {
private String indexDir;
private String indexType="add";
 public void run() {
// TODO Auto-generated method stub
if("add".equals(indexType))
normalIndex();
else if ("init".equals(indexType)) reIndexAll();
}
public void normalIndex()
 {
 try {
Date start = new Date();
int num=0;
IndexWriter writer=new IndexWriter(indexDir,new StandardAnalyzer(),false);
//NewsDir dir=NewsDir.readBySn();
String scope="(needIndex<2) or(needIndex is null)";
IPageList pList=NewsUtil.pageList(scope,1,50);
for(int p=0;p<pList.getPages();p++)
 {
pList=NewsUtil.pageList(scope,p,100);
List list=pList.getResult();
for(int i=0;i<list.size();i++)
 {
NewsDoc doc=(NewsDoc)list.get(i);
writer.addDocument(newsdoc2lucenedoc(doc));
num++;
}
}
writer.optimize();
writer.close();
EasyJDB.getInstance().execute("update NewsDoc set needIndex=2 where "+scope);
Date end = new Date();
System.out.print("新增索引"+num+"條信息,一共花:"+(end.getTime() - start.getTime())/60000+"分鐘!");
}
catch(Exception e)
 {
e.printStackTrace();
}
}
public void reIndexAll()
 {
 try {
Date start = new Date();
int num=0;
IndexWriter writer=new IndexWriter(indexDir,new StandardAnalyzer(),true);
NewsDir dir=NewsDir.readBySn("easyjf");
IPageList pList=NewsUtil.pageList(dir,1,50);
for(int p=0;p<pList.getPages();p++)
 {
pList=NewsUtil.pageList(dir,p,100);
List list=pList.getResult();
for(int i=0;i<list.size();i++)
 {
NewsDoc doc=(NewsDoc)list.get(i);
writer.addDocument(newsdoc2lucenedoc(doc));
num++;
}
}
writer.optimize();
writer.close();
EasyJDB.getInstance().execute("update NewsDoc set needIndex=2 where dirPath like 'easyjf%'");
Date end = new Date();
System.out.print("全部重新做了一次索引,一共處理了"+num+"條信息,花:"+(end.getTime() - start.getTime())/60000+"分鐘!");
}
catch(Exception e)
 {
e.printStackTrace();
}
}
private Document newsdoc2lucenedoc(NewsDoc doc)
 {
Document lDoc=new Document();
lDoc.add(new Field("title",doc.getTitle(),Field.Store.YES,Field.Index.TOKENIZED));
lDoc.add(new Field("content",doc.getContent(),Field.Store.YES,Field.Index.TOKENIZED));
lDoc.add(new Field("url",doc.getRemark(),Field.Store.YES,Field.Index.NO));
lDoc.add(new Field("cid",doc.getCid(),Field.Store.YES,Field.Index.NO));
lDoc.add(new Field("source",doc.getSource(),Field.Store.YES,Field.Index.NO));
lDoc.add(new Field("inputTime",doc.getInputTime().toString(),Field.Store.YES,Field.Index.NO));
return lDoc;
}
 public String getIndexDir() {
return indexDir;
}
 public void setIndexDir(String indexDir) {
this.indexDir = indexDir;
}
 public String getIndexType() {
return indexType;
}
 public void setIndexType(String indexType) {
this.indexType = indexType;
}
}
二、使用Lucene實現全文搜索
下面是MyRssSearch類的源碼,該類主要實現使用Lucene中Searcher及QueryParser實現從索引庫中搜索關鍵詞。
package com.easyjf.lucene;
import java.util.List;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.queryParser.MultiFieldQueryParser;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.Hits;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Searcher;
import com.easyjf.search.MyRssUtil;
import com.easyjf.search.SearchContent;
import com.easyjf.web.tools.IPageList;
import com.easyjf.web.tools.PageList;
 public class MyRssSearch {
private String indexDir;
IndexReader ir;
Searcher search;
public IPageList search(String key,int pageSize,int currentPage)
 {
IPageList pList=new PageList(new HitsQuery(doSearch(key)));
pList.doList(pageSize,currentPage,"","",null);
if(pList!=null)
 {
List list=pList.getResult();
 if(list!=null) {
for(int i=0;i<list.size();i++)
 {
list.set(i,lucene2searchObj((Document)list.get(i),key));
}
}
}
 try {
if(search!=null)search.close();
if(ir!=null)ir.close();
}
catch(Exception e)
 {
e.printStackTrace();
}
return pList;
}
private SearchContent lucene2searchObj(Document doc,String key)
 {
SearchContent searchObj=new SearchContent();
String title=doc.getField("title").stringValue();
searchObj.setTitle(title.replaceAll(key,"<font color=red>"+key+"</font>"));
searchObj.setTvalue(doc.getField("cid").stringValue());
searchObj.setUrl(doc.getField("url").stringValue());
searchObj.setSource(doc.getField("source").stringValue());
searchObj.setLastUpdated(doc.getField("inputTime").stringValue());
searchObj.setIntro(MyRssUtil.content2intro(doc.getField("content").stringValue(),key));
return searchObj;
}
public Hits doSearch(String key)
 {
Hits hits=null;
 try {
ir=IndexReader.open(indexDir);
search=new IndexSearcher(ir);
 String fields[]= {"title","content"};
QueryParser parser=new MultiFieldQueryParser(fields,new StandardAnalyzer());
Query query=parser.parse(key);
hits=search.search(query);
}
catch(Exception e)
 {
e.printStackTrace();
}
//System.out.println("搜索結果:"+hits.length());
return hits;
}
 public String getIndexDir() {
return indexDir;
}
 public void setIndexDir(String indexDir) {
this.indexDir = indexDir;
}
}

在上面的代碼中,search方法返回一個封裝了分頁查詢結果的IPageList,IPageList是EasyJWeb Tools業務引擎中的分頁引擎,對于IPageList的使用,請看本人寫的這篇文章《EasyJWeb Tools中業務引擎分頁的設計實現》:
我們針對Lucene的的查詢結果Hits結構,寫了一個查詢器HitsQuery。代碼如下所示:
package com.easyjf.lucene;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.apache.lucene.search.Hits;
import com.easyjf.web.tools.IQuery;
 public class HitsQuery implements IQuery {
private int begin=0;
private int max=0;
private Hits hits;
public HitsQuery()
 {
}
public HitsQuery(Hits hits)
 {
if(hits!=null)
 {
this.hits=hits;
this.max=hits.length();
}
}
 public int getRows(String arg0) {
// TODO Auto-generated method stub
return (hits==null?0:hits.length());
}
 public List getResult(String arg0) {
// TODO Auto-generated method stub
List list=new ArrayList();
for(int i=begin;i<(begin+max)&&(i<hits.length());i++)
 {
 try {
list.add(hits.doc(i));
}
catch(Exception e)
 {
e.printStackTrace();
}
}
return list;
}
 public void setFirstResult(int begin) {
// TODO Auto-generated method stub
this.begin=begin;
}
 public void setMaxResults(int max) {
// TODO Auto-generated method stub
this.max=max;
}
 public void setParaValues(Collection arg0) {
// TODO Auto-generated method stub
}
 public List getResult(String condition, int begin, int max) {
// TODO Auto-generated method stub
if((begin>=0)&&(begin<max))this.begin=begin;
if(!(max>hits.length()))this.max=max;
return getResult(condition);
}
}
三、Web調用
下面我們來看看在Web中如果調用商業邏輯層的全文檢索功能。下面是處理用戶請請的Action中關于搜索部分的源碼:
package com.easyjf.news.action;
 public class SearchAction implements IWebAction {
public Page doSearch(WebForm form,Module module)throws Exception
  {
String key=CommUtil.null2String(form.get("v"));
key=URLDecoder.decode(URLEncoder.encode(key,"ISO8859_1"),"utf-8");
form.set("v",key);
form.addResult("v2",URLEncoder.encode(key,"utf-8"));
 if(key.getBytes().length>2) {
String orderBy=CommUtil.null2String(form.get("order"));
int currentPage=CommUtil.null2Int(form.get("page"));
int pageSize=CommUtil.null2Int(form.get("pageSize"));
if(currentPage<1)currentPage=1;
if(pageSize<1)pageSize=15;
SearchEngine search=new SearchEngine(key,orderBy,pageSize,currentPage);
search.getLuceneSearch().setIndexDir(Globals.APP_BASE_DIR+"/WEB-INF/index");
search.doSearchByLucene();
IPageList pList=search.getResult();
 if(pList!=null && pList.getRowCount()>0) {
form.addResult("list",pList.getResult());
form.addResult("pages",new Integer(pList.getPages()));
form.addResult("rows",new Integer(pList.getRowCount()));
form.addResult("page",new Integer(pList.getCurrentPage()));
form.addResult("gotoPageHTML",CommUtil.showPageHtml(pList.getCurrentPage(),pList.getPages()));
}
else
 {
form.addResult("notFound","true");//找不到數據
}
}
else
form.addResult("errMsg","您輸入的關鍵字太短!");
form.addResult("hotSearch",SearchEngine.getHotSearch(20));
return null;
}
}
其中調用的SearchEngine類中有關Lucene部分的源碼:
public class SearchEngine {
private MyRssSearch luceneSearch=new MyRssSearch();
public void doSearchByLucene()
{
SearchKey keyObj=readCache();
if(keyObj!=null){
result=luceneSearch.search(key,pageSize,currentPage);
if(updateStatus){
keyObj.setReadTimes(new Integer(keyObj.getReadTimes().intValue()+1));
keyObj.update();
}
}
else//緩存中沒有該關鍵字信息,生成關鍵字搜索結果
{
keyObj=new SearchKey();
keyObj.setTitle(key);
keyObj.setLastUpdated(new Date());
keyObj.setReadTimes(new Integer(1));
keyObj.setStatus(new Integer(0));
keyObj.setSequence(new Integer(1));
keyObj.setVdate(new Date());
keyObj.save();
result=luceneSearch.search(key,pageSize,currentPage);;
}
}
}
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