邊學邊記（二） 索引查詢

lucene 索引查詢 步驟 首選我們要打開 索引的所在目錄 索引目錄可以是物理磁盤目錄也可以是RAM 內存中的索引目錄

Eclipse的全文檢索好像也是lucene做的 具體的沒去看過代碼

Ecilpse中的Maven的插件頁使用了lucene對依賴庫做了索引。

根據定位的索引目錄 創建IndexReader 來讀取index了，具體方法：

 

IndexReader open(final Directory directory, boolean readOnly)

參數一就是第一步當中我們打開的索引目錄了，第二個參數也很明白了 一般爲true吧 單純的讀取器一般也不會來修改index信息吧

 

第三部就是創建索引檢索器了IndexSearcher

lucene提供了三個構造方法來實例化檢索器

/** Creates a searcher searching the index in the named * directory, with readOnly=true * @throws CorruptIndexException if the index is corrupt * @throws IOException if there is a low-level IO error * @param path directory where IndexReader will be opened */ public IndexSearcher(Directory path) throws CorruptIndexException, IOException { this(IndexReader.open(path, true), true); } /** Creates a searcher searching the index in the named * directory. You should pass readOnly=true, since it * gives much better concurrent performance, unless you * intend to do write operations (delete documents or * change norms) with the underlying IndexReader. * @throws CorruptIndexException if the index is corrupt * @throws IOException if there is a low-level IO error * @param path directory where IndexReader will be opened * @param readOnly if true, the underlying IndexReader * will be opened readOnly */ public IndexSearcher(Directory path, boolean readOnly) throws CorruptIndexException, IOException { this(IndexReader.open(path, readOnly), true); } /** Creates a searcher searching the provided index. */ public IndexSearcher(IndexReader r) { this(r, false); } /** Expert: directly specify the reader, subReaders and * their docID starts. * * <p><b>NOTE:</b> This API is experimental and * might change in incompatible ways in the next * release.</font></p> */ public IndexSearcher(IndexReader reader, IndexReader[] subReaders, int[] docStarts) { this.reader = reader; this.subReaders = subReaders; this.docStarts = docStarts; closeReader = false; }

 

看這幾個公開的構造方法最終都是用的其私有構造方法

private IndexSearcher(IndexReader r, boolean closeReader)

從代碼中得知 closeReader 在外部引入reader的時候是false 其他的指明瞭directory的都是爲true以便由searcher來管理reader

 

編寫檢索的基類Searcher

 

/**************** * *Create Class:Searcher.java *Author:a276202460 *Create at:2010-5-25 */ package com.rich.lucene.searcher; import java.io.File; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Calendar; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.standard.StandardAnalyzer; import org.apache.lucene.document.Document; import org.apache.lucene.index.IndexReader; import org.apache.lucene.search.IndexSearcher; import org.apache.lucene.search.Query; import org.apache.lucene.search.ScoreDoc; import org.apache.lucene.search.TopDocs; import org.apache.lucene.search.TopScoreDocCollector; import org.apache.lucene.store.Directory; import org.apache.lucene.store.FSDirectory; import org.apache.lucene.util.Version; import com.rich.lucene.util.IndexKeys; public class Searcher { private DateFormat df = new SimpleDateFormat("MM/dd/yyyy"); public Directory getDirectory() throws Exception { Directory directory = null; directory = FSDirectory.open(new File(IndexKeys.TXT_INDEX_BASE_DIR + "//index2")); return directory; } public IndexReader getReader(Directory directory) throws Exception { return IndexReader.open(directory, true); } public Analyzer getAnalyzer() throws Exception { return new StandardAnalyzer(Version.LUCENE_CURRENT); } public void Close(Directory directory, IndexReader reader) throws Exception { if (reader != null) reader.close(); if (directory != null) directory.close(); } public void Search(Query query) throws Exception { Directory directory = null; IndexReader reader = null; try { //獲得索引目錄 directory = this.getDirectory(); //創建索引的讀取器 reader = this.getReader(directory); //根據讀取器創建查詢器 IndexSearcher searcher = new IndexSearcher(reader); /* 結果集合容器 一般必須將所有的查詢結果都查詢出來,如果期望的查詢容器設置爲 * 10000 甚至更多那麼你就該想想內存的使用了 單純的定義一個幾萬的空數組內存的 * 分配也不可小看。 * * TopScoreDocCollector .create(int numHits, boolean docsScoredInOrder) 第一個就是期望的最多查詢結果數 第二個參數：是否按照doc的得分對結果排序 */ TopScoreDocCollector results = TopScoreDocCollector .create(10, true); long starttime = System.currentTimeMillis(); /* * 根據Query將查詢結果放入到results集合中，results集合查詢出來的信息 * 有總的結果數 TotalHits 和score 得分的前N個結果的doc的索引 N即爲results * 集合中執行的結果數和真實結果數種的Max值 */ searcher.search(query, results); System.out.println(">>>>>>>>>>>> User Query:" + query); System.out.println(">>>>>>>>>>>> Query Use:" + (System.currentTimeMillis() - starttime) + "ms"); System.out.println(">>>>>>>>>>>> Total Result:" + results.getTotalHits()); TopDocs topdocs = results.topDocs(); ScoreDoc[] docs = topdocs.scoreDocs; Document doc = null; for (int i = 0; i < docs.length; i++) { doc = searcher.doc(docs[i].doc); System.out.println("************************************"); System.out.println("Result Score:" + docs[i].score +"Result Type:" + doc.get(IndexKeys.TEST_TYPE) + " Result Biz:" + doc.get(IndexKeys.TEST_BIZ) + "/nResult No:" + doc.get(IndexKeys.TEST_NUMBERIC) + " Result StartDate:" + getDate(doc.get(IndexKeys.TEST_STARTDATE)) + " Result EndDate:" + getDate(doc.get(IndexKeys.TEST_ENDDATE))); System.out.println("----Result Content:" + doc.get(IndexKeys.TEST_CONTENT) + "---"); System.out.println("************************************"); } } finally { this.Close(directory, reader); } } private String getDate(String longstr) { long time = Long.parseLong(longstr); Calendar c = Calendar.getInstance(); c.setTimeInMillis(time); return df.format(c.getTime()); } }

 

好了有了基類中的Search(Query query) 方法我們就可以測試各種的query 規則了

lucene的所有Query

 

 

 

 

 

API裏兩處subclass list 慢慢看吧 好些單詞都不知道 還得查字典 那是以後的事了