documentiterator.java

这是一个用于测试用的搜索引擎的案例

package ir.vsr;

import java.io.*;
import java.util.*;
import java.lang.*;

/** An object for iterating over a set of documents in a directory.
 * Produces DocumentFile objects that are either TextFileDocuments
 * or HTMFileDocuments depending on wether docType is TYPE_TEXT
 * or TYPE_HTML
 *
 * @author Ray Mooney
*/

public class DocumentIterator {

    /** docType for ASCII text files */
    public static final short TYPE_TEXT = 0;
    /** docType for HTML files */
    public static final short TYPE_HTML = 1;

    /** An array of files in the directory */
    protected File[] files = null;
    /** The current position of the iterator in this array */
    protected int position = 0;
    /** The type of documents to be created */
    protected short docType = TYPE_TEXT;
    /** Whether tokens should be stemmed with Porter stemmer */
    protected boolean stem = false;
    
    /** Create an iterator with these attributes
     * @param dirFile The directory to use as a source of documents.
     * @param docType The type of Document to create. e.g. TYPE_TEXT or TYPE_HTML
     * @param stem Whether tokens should be stemmed with Porter stemmer.
     * @param filter  A filter to select a subset of the docs in the directory
     */
    public DocumentIterator(File dirFile, short docType, boolean stem, FilenameFilter filter) {
	// Get the files in this directory 
	if (filter != null)
	    files = dirFile.listFiles(filter);
	else 
	    files = dirFile.listFiles();
	// Initialize the position and docType
	position = 0;
	this.docType = docType;
	this.stem = stem;
    }

    /** Create an iterator with these attributes
     * @param dirFile The directory to use as a source of documents.
     * @param docType The type of Document to create. e.g. TYPE_TEXT or TYPE_HTML
     * @param stem Whether tokens should be stemmed with Porter stemmer.
     */
    public DocumentIterator(File dirFile, short docType, boolean stem) {
	this(dirFile, docType, stem, null);
    }

    /** Create an iterator for TexFileDocuments 
     * @param dirFile The directory to use as a source of documents.
     */
    public DocumentIterator(File dirFile) {
	this(dirFile, TYPE_TEXT, false);
    }

    /** Get the next document */
    public FileDocument nextDocument() {
	if (position >= files.length)
	    return null;
	FileDocument doc = null;
	// Create the correct type of FileDocument based on docType
	switch(docType) {
	case TYPE_TEXT:
	    doc = new TextFileDocument(files[position], stem);
	    break;
	case TYPE_HTML:
	    doc = new HTMLFileDocument(files[position], stem);
	    break;
	}
	// Reset position to the next file
	position++;
	return doc;
    }

    /** Returns true iff there are more documents in this directory */
    public boolean hasMoreDocuments() {
	if (files != null && position < files.length)
	    return true;
	else
	    return false;
    }

    /** Test by printing the bag-of-words for each file in the given directory */
    public static void main(String[] args) {
	String dirName = args[0];
	DocumentIterator docIter = new DocumentIterator(new File(dirName));
	while(docIter.hasMoreDocuments()) {
	    FileDocument doc = docIter.nextDocument();
	    System.out.println("\n" + doc.file);
	    doc.printVector();
	}
    }

}