Lucene 3.0 入门实例

lucene3.0已于2009-11-25发布啦，但网上的入门实例都是针对lucene3.0以前的，相对于以前的版本，貌似改动不小。

本人从零开始学习《lucene in action中文版》，并结合lucene3.0文档写了个入门实例，可供像我一样直接从lucene3.0开始学习的初学者参考！（变化大的地方用蓝字标出来了）

入门实例：

1.预处理：先把网上下载的一个《三国演义》电子书“三国演义.txt”（可用其他代替，呵呵）切割成多个小文件。
/**
* @author ht
* 预处理
*
*/
public class FilePreprocess {
public static void main(String[] arg){
String outputpath = "D:\\test\\small\\";//小文件存放路径
String filename = "D:\\test\\三国演义.txt";//原文件存放路径
if(!new File(outputpath).exists()){
new File(outputpath).mkdirs();
}

splitToSmallFiles(new File(filename), outputpath);
}
/**大文件切割为小的
* @param file
* @param outputpath
*/
public static void splitToSmallFiles(File file ,String outputpath){
int filePointer = 0;
int MAX_SIZE = 10240;//小文件大小
String filename = "output";//小文件的文件名前缀

BufferedWriter writer = null;
try {
BufferedReader reader = new BufferedReader(new FileReader(file));
StringBuffer buffer = new StringBuffer();
String line = reader.readLine();
while(line != null){
buffer.append(line).append("\r\n");
if(buffer.toString().getBytes().length>=MAX_SIZE){
writer = new BufferedWriter(new FileWriter(outputpath+filename+filePointer+".txt"));
writer.write(buffer.toString());
writer.close();
filePointer++;
buffer=new StringBuffer();
}
line = reader.readLine();              
}
writer = new BufferedWriter(new FileWriter(outputpath+filename+filePointer+".txt"));
writer.write(buffer.toString());
writer.close();
System.out.println("The file hava splited to small files !");
} catch (FileNotFoundException e) {
System.out.println("file not found !");
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}      
}

2.用lucene3.0生成索引类:用lencene3.0对生成的多个小文件进行索引，中文分词用的是lucene3.0自带的StandardAnalyzer.
/**
* @author ht
* 索引生成
*
*/
public class Indexer {
private static String INDEX_DIR = "D:\\test\\index";//索引存放目录
private static String DATA_DIR = "D:\\test\\small\\";//小文件存放的目录

public static void main(String[] args) throws Exception {

long start = new Date().getTime();
int numIndexed = index(new File(INDEX_DIR), new File(DATA_DIR));//调用index方法
long end = new Date().getTime();
System.out.println("Indexing " + numIndexed + " files took " + (end - start) + " milliseconds");
}

/**索引dataDir下的.txt文件，并储存在indexDir下，返回索引的文件数量
* @param indexDir
* @param dataDir
* @return int
* @throws IOException
*/
public static int index(File indexDir, File dataDir) throws IOException {

if (!dataDir.exists() || !dataDir.isDirectory()) {
throw new IOException(dataDir + " does not exist or is not a directory");
}

IndexWriter writer = new IndexWriter(FSDirectory.open(indexDir), new StandardAnalyzer(Version.LUCENE_CURRENT), true,   
IndexWriter.MaxFieldLength.LIMITED);

indexDirectory(writer, dataDir);//调用indexDirectory方法
int numIndexed = writer.numDocs();
writer.optimize();
writer.close();
return numIndexed;
}

/**循环遍历目录下的所有.txt文件并进行索引
* @param writer
* @param dir
* @throws IOException
*/
private static void indexDirectory(IndexWriter writer, File dir)
throws IOException {

File[] files = dir.listFiles();

for (int i = 0; i < files.length; i++) {
File f = files[i];
if (f.isDirectory()) {
indexDirectory(writer, f); // recurse
} else if (f.getName().endsWith(".txt")) {
indexFile(writer, f);
}
}
}

/**对单个txt文件进行索引
* @param writer
* @param f
* @throws IOException
*/
private static void indexFile(IndexWriter writer, File f)
throws IOException {

if (f.isHidden() || !f.exists() || !f.canRead()) {
return;
}

System.out.println("Indexing " + f.getCanonicalPath());
Document doc = new Document();
doc.add(new Field("contents",new FileReader(f)));
doc.add(new Field("filename",f.getCanonicalPath(),Field.Store.YES, Field.Index.ANALYZED));

writer.addDocument(doc);
}
}


3.查询类：查询“玄德”！
/**
* @author ht
* 查询
*
*/
public class Searcher {
private static String INDEX_DIR = "D:\\test\\index\\";//索引所在的路径
private static String KEYWORD = "玄德";//关键词
private static int TOP_NUM = 100;//显示前100条结果

public static void main(String[] args) throws Exception {
File indexDir = new File(INDEX_DIR);
if (!indexDir.exists() || !indexDir.isDirectory()) {
throw new Exception(indexDir +
" does not exist or is not a directory.");
}
search(indexDir, KEYWORD);//调用search方法进行查询
}
/**查询
* @param indexDir
* @param q
* @throws Exception
*/
public static void search(File indexDir, String q) throws Exception {
IndexSearcher is = new IndexSearcher(FSDirectory.open(indexDir),true);//read-only
String field = "contents";

QueryParser parser = new QueryParser(Version.LUCENE_CURRENT, field, new StandardAnalyzer(Version.LUCENE_CURRENT));
Query query = parser.parse(q);

TopScoreDocCollector collector = TopScoreDocCollector.create(TOP_NUM , false);

long start = new Date().getTime();// start time

is.search(query, collector);
ScoreDoc[] hits = collector.topDocs().scoreDocs;

System.out.println(hits.length);
for (int i = 0; i < hits.length; i++) {
Document doc = is.doc(hits[i].doc);//new method is.doc()
System.out.println(doc.getField("filename")+"   "+hits[i].toString()+" ");
}
long end = new Date().getTime();//end time

System.out.println("Found " + collector.getTotalHits() +
" document(s) (in " + (end - start) +
" milliseconds) that matched query '" +
q + "':");
}
}