Lucene example source code file (FileSwitchDirectory.java)

This example Lucene source code file (FileSwitchDirectory.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

arraylist, deprecated, directory, directory, fileswitchdirectory, hashset, io, ioexception, ioexception, list, override, override, set, string, string, util

The Lucene FileSwitchDirectory.java source code

package org.apache.lucene.store;

/**
 * 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.IOException;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.HashSet;

/**
 * Expert: A Directory instance that switches files between
 * two other Directory instances.

 * <p>Files with the specified extensions are placed in the
 * primary directory; others are placed in the secondary
 * directory.  The provided Set must not change once passed
 * to this class, and must allow multiple threads to call
 * contains at once.</p>
 *
 * @lucene.experimental
 */

public class FileSwitchDirectory extends Directory {
  private final Directory secondaryDir;
  private final Directory primaryDir;
  private final Set<String> primaryExtensions;
  private boolean doClose;

  public FileSwitchDirectory(Set<String> primaryExtensions, Directory primaryDir, Directory secondaryDir, boolean doClose) {
    this.primaryExtensions = primaryExtensions;
    this.primaryDir = primaryDir;
    this.secondaryDir = secondaryDir;
    this.doClose = doClose;
    this.lockFactory = primaryDir.getLockFactory();
  }

  /** Return the primary directory */
  public Directory getPrimaryDir() {
    return primaryDir;
  }
  
  /** Return the secondary directory */
  public Directory getSecondaryDir() {
    return secondaryDir;
  }
  
  @Override
  public void close() throws IOException {
    if (doClose) {
      try {
        secondaryDir.close();
      } finally { 
        primaryDir.close();
      }
      doClose = false;
    }
  }
  
  @Override
  public String[] listAll() throws IOException {
    Set<String> files = new HashSet();
    for(String f : primaryDir.listAll()) {
      files.add(f);
    }
    for(String f : secondaryDir.listAll()) {
      files.add(f);
    }
    return files.toArray(new String[files.size()]);
  }

  /** Utility method to return a file's extension. */
  public static String getExtension(String name) {
    int i = name.lastIndexOf('.');
    if (i == -1) {
      return "";
    }
    return name.substring(i+1, name.length());
  }

  private Directory getDirectory(String name) {
    String ext = getExtension(name);
    if (primaryExtensions.contains(ext)) {
      return primaryDir;
    } else {
      return secondaryDir;
    }
  }

  @Override
  public boolean fileExists(String name) throws IOException {
    return getDirectory(name).fileExists(name);
  }

  @Override
  public long fileModified(String name) throws IOException {
    return getDirectory(name).fileModified(name);
  }

  @Deprecated
  @Override
  /*  @deprecated Lucene never uses this API; it will be
   *  removed in 4.0. */
  public void touchFile(String name) throws IOException {
    getDirectory(name).touchFile(name);
  }

  @Override
  public void deleteFile(String name) throws IOException {
    getDirectory(name).deleteFile(name);
  }

  @Override
  public long fileLength(String name) throws IOException {
    return getDirectory(name).fileLength(name);
  }

  @Override
  public IndexOutput createOutput(String name) throws IOException {
    return getDirectory(name).createOutput(name);
  }

  @Deprecated
  @Override
  public void sync(String name) throws IOException {
    sync(Collections.singleton(name));
  }

  @Override
  public void sync(Collection<String> names) throws IOException {
    List<String> primaryNames = new ArrayList();
    List<String> secondaryNames = new ArrayList();

    for (String name : names)
      if (primaryExtensions.contains(getExtension(name)))
        primaryNames.add(name);
      else
        secondaryNames.add(name);

    primaryDir.sync(primaryNames);
    secondaryDir.sync(secondaryNames);
  }

  @Override
  public IndexInput openInput(String name) throws IOException {
    return getDirectory(name).openInput(name);
  }
}