Lucene example source code file (IndexFileNameFilter.java)

This example Lucene source code file (IndexFileNameFilter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lucene tags/keywords

filenamefilter, filenamefilter, hashset, hashset, indexfilenamefilter, indexfilenamefilter, io, string, string, util

The Lucene IndexFileNameFilter.java source code

package org.apache.lucene.index;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.File;
import java.io.FilenameFilter;
import java.util.HashSet;

/**
 * Filename filter that accept filenames and extensions only created by Lucene.
 *
 * @lucene.internal
 */
public class IndexFileNameFilter implements FilenameFilter {

  private static IndexFileNameFilter singleton = new IndexFileNameFilter();
  private HashSet<String> extensions;
  private HashSet<String> extensionsInCFS;

  // Prevent instantiation.
  private IndexFileNameFilter() {
    extensions = new HashSet<String>();
    for (String ext : IndexFileNames.INDEX_EXTENSIONS) {
      extensions.add(ext);
    }
    extensionsInCFS = new HashSet<String>();
    for (String ext : IndexFileNames.INDEX_EXTENSIONS_IN_COMPOUND_FILE) {
      extensionsInCFS.add(ext);
    }
  }

  /* (non-Javadoc)
   * @see java.io.FilenameFilter#accept(java.io.File, java.lang.String)
   */
  public boolean accept(File dir, String name) {
    int i = name.lastIndexOf('.');
    if (i != -1) {
      String extension = name.substring(1+i);
      if (extensions.contains(extension)) {
        return true;
      } else if (extension.startsWith("f") &&
                 extension.matches("f\\d+")) {
        return true;
      } else if (extension.startsWith("s") &&
                 extension.matches("s\\d+")) {
        return true;
      }
    } else {
      if (name.equals(IndexFileNames.DELETABLE)) return true;
      else if (name.startsWith(IndexFileNames.SEGMENTS)) return true;
    }
    return false;
  }

  /**
   * Returns true if this is a file that would be contained
   * in a CFS file.  This function should only be called on
   * files that pass the above "accept" (ie, are already
   * known to be a Lucene index file).
   */
  public boolean isCFSFile(String name) {
    int i = name.lastIndexOf('.');
    if (i != -1) {
      String extension = name.substring(1+i);
      if (extensionsInCFS.contains(extension)) {
        return true;
      }
      if (extension.startsWith("f") &&
          extension.matches("f\\d+")) {
        return true;
      }
    }
    return false;
  }

  public static IndexFileNameFilter getFilter() {
    return singleton;
  }
}