lucene3.0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。
本人从头开始学习lucene，现在用的是《lucene in action中文版》，结合lucene3.0文档写了个入门实例，可供像我一样直接从lucene3.0开始学习的新手参考！

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;
	String filename = "output";

	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);//有变化的地方
    
    indexDirectory(writer, dataDir);
    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)));//有变化的地方
    doc.add(new Field("filename",f.getCanonicalPath(),Field.Store.YES, Field.Index.ANALYZED));//有变化的地方
 
    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));//有变化的地方
    Query query = parser.parse(q);

    TopScoreDocCollector collector = TopScoreDocCollector.create(TOP_NUM , false);//有变化的地方
    
    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 + "':");
  }
}

4.结果就不贴啦，反正能运行就是啦