fsdirectory.java

中文分词,中科院分词的改装版。使用java调用dll来实现的。

package org.apache.lucene.store;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed 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.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Hashtable;

import org.apache.lucene.index.IndexFileNameFilter;

/**
 * Straightforward implementation of {@link Directory} as a directory of files.
 *
 * @see Directory
 * @author Doug Cutting
 */
public class FSDirectory extends Directory {
    
  /** This cache of directories ensures that there is a unique Directory
   * instance per path, so that synchronization on the Directory can be used to
   * synchronize access between readers and writers.
   *
   * This should be a WeakHashMap, so that entries can be GC'd, but that would
   * require Java 1.2.  Instead we use refcounts...
   */
  private static final Hashtable DIRECTORIES = new Hashtable();

  private static boolean disableLocks = false;

  /**
   * Set whether Lucene's use of lock files is disabled. By default, 
   * lock files are enabled. They should only be disabled if the index
   * is on a read-only medium like a CD-ROM.
   */
  public static void setDisableLocks(boolean doDisableLocks) {
    FSDirectory.disableLocks = doDisableLocks;
  }

  /**
   * Returns whether Lucene's use of lock files is disabled.
   * @return true if locks are disabled, false if locks are enabled.
   */
  public static boolean getDisableLocks() {
    return FSDirectory.disableLocks;
  }

  /**
   * Directory specified by <code>org.apache.lucene.lockDir</code>
   * or <code>java.io.tmpdir</code> system property
   */
  public static final String LOCK_DIR =
    System.getProperty("org.apache.lucene.lockDir",
      System.getProperty("java.io.tmpdir"));

  /** The default class which implements filesystem-based directories. */
  private static Class IMPL;
  static {
    try {
      String name =
        System.getProperty("org.apache.lucene.FSDirectory.class",
                           FSDirectory.class.getName());
      IMPL = Class.forName(name);
    } catch (ClassNotFoundException e) {
      throw new RuntimeException("cannot load FSDirectory class: " + e.toString(), e);
    } catch (SecurityException se) {
      try {
        IMPL = Class.forName(FSDirectory.class.getName());
      } catch (ClassNotFoundException e) {
        throw new RuntimeException("cannot load default FSDirectory class: " + e.toString(), e);
      }
    }
  }

  private static MessageDigest DIGESTER;

  static {
    try {
      DIGESTER = MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException e) {
        throw new RuntimeException(e.toString(), e);
    }
  }

  /** A buffer optionally used in renameTo method */
  private byte[] buffer = null;

  /** Returns the directory instance for the named location.
   *
   * <p>Directories are cached, so that, for a given canonical path, the same
   * FSDirectory instance will always be returned.  This permits
   * synchronization on directories.
   *
   * @param path the path to the directory.
   * @param create if true, create, or erase any existing contents.
   * @return the FSDirectory for the named file.  */
  public static FSDirectory getDirectory(String path, boolean create)
      throws IOException {
    return getDirectory(new File(path), create);
  }

  /** Returns the directory instance for the named location.
   *
   * <p>Directories are cached, so that, for a given canonical path, the same
   * FSDirectory instance will always be returned.  This permits
   * synchronization on directories.
   *
   * @param file the path to the directory.
   * @param create if true, create, or erase any existing contents.
   * @return the FSDirectory for the named file.  */
  public static FSDirectory getDirectory(File file, boolean create)
    throws IOException {
    file = new File(file.getCanonicalPath());
    FSDirectory dir;
    synchronized (DIRECTORIES) {
      dir = (FSDirectory)DIRECTORIES.get(file);
      if (dir == null) {
        try {
          dir = (FSDirectory)IMPL.newInstance();
        } catch (Exception e) {
          throw new RuntimeException("cannot load FSDirectory class: " + e.toString(), e);
        }
        dir.init(file, create);
        DIRECTORIES.put(file, dir);
      } else if (create) {
        dir.create();
      }
    }
    synchronized (dir) {
      dir.refCount++;
    }
    return dir;
  }

  private File directory = null;
  private int refCount;
  private File lockDir;

  protected FSDirectory() {};                     // permit subclassing

  private void init(File path, boolean create) throws IOException {
    directory = path;

    if (LOCK_DIR == null) {
      lockDir = directory;
    }
    else {
      lockDir = new File(LOCK_DIR);
    }
    // Ensure that lockDir exists and is a directory.
    if (!lockDir.exists()) {
      if (!lockDir.mkdirs())
        throw new IOException("Cannot create directory: " + lockDir.getAbsolutePath());
    } else if (!lockDir.isDirectory()) {
      throw new IOException("Found regular file where directory expected: " + 
          lockDir.getAbsolutePath());
    }
    if (create) {
      create();
    }

    if (!directory.isDirectory())
      throw new IOException(path + " not a directory");
  }

  private synchronized void create() throws IOException {
    if (!directory.exists())
      if (!directory.mkdirs())
        throw new IOException("Cannot create directory: " + directory);

    if (!directory.isDirectory())
      throw new IOException(directory + " not a directory");

    String[] files = directory.list(new IndexFileNameFilter());            // clear old files
    if (files == null)
      throw new IOException("Cannot read directory " + directory.getAbsolutePath());
    for (int i = 0; i < files.length; i++) {
      File file = new File(directory, files[i]);
      if (!file.delete())
        throw new IOException("Cannot delete " + file);
    }

    String lockPrefix = getLockPrefix().toString(); // clear old locks
    files = lockDir.list();
    if (files == null)
      throw new IOException("Cannot read lock directory " + lockDir.getAbsolutePath());
    for (int i = 0; i < files.length; i++) {
      if (!files[i].startsWith(lockPrefix))
        continue;
      File lockFile = new File(lockDir, files[i]);
      if (!lockFile.delete())
        throw new IOException("Cannot delete " + lockFile);
    }
  }

  /** Returns an array of strings, one for each file in the directory. */
  public String[] list() {
    return directory.list();
  }

  /** Returns true iff a file with the given name exists. */
  public boolean fileExists(String name) {
    File file = new File(directory, name);
    return file.exists();
  }

  /** Returns the time the named file was last modified. */
  public long fileModified(String name) {
    File file = new File(directory, name);
    return file.lastModified();
  }

  /** Returns the time the named file was last modified. */
  public static long fileModified(File directory, String name) {
    File file = new File(directory, name);
    return file.lastModified();
  }

  /** Set the modified time of an existing file to now. */
  public void touchFile(String name) {
    File file = new File(directory, name);
    file.setLastModified(System.currentTimeMillis());
  }

  /** Returns the length in bytes of a file in the directory. */
  public long fileLength(String name) {
    File file = new File(directory, name);
    return file.length();
  }

  /** Removes an existing file in the directory. */
  public void deleteFile(String name) throws IOException {
    File file = new File(directory, name);
    if (!file.delete())
      throw new IOException("Cannot delete " + file);
  }

  /** Renames an existing file in the directory. */
  public synchronized void renameFile(String from, String to)
      throws IOException {
    File old = new File(directory, from);
    File nu = new File(directory, to);

    /* This is not atomic.  If the program crashes between the call to