Lucene example source code file (WindowsDirectory.java)

This example Lucene source code file (WindowsDirectory.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

bufferedindexinput, default_buffersize, eof, file, io, ioexception, ioexception, lockfactory, object, override, override, windowsdirectory, windowsdirectory, windowsindexinput, windowsindexinput

The Lucene WindowsDirectory.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.File;
import java.io.IOException;
import org.apache.lucene.store.Directory; // javadoc
import org.apache.lucene.store.NativeFSLockFactory; // javadoc

/**
 * Native {@link Directory} implementation for Microsoft Windows.
 * <p>
 * Steps:
 * <ol> 
 *   <li>Compile the source code to create WindowsDirectory.dll:
 *       <blockquote>
 * c:\mingw\bin\g++ -Wall -D_JNI_IMPLEMENTATION_ -Wl,--kill-at 
 * -I"%JAVA_HOME%\include" -I"%JAVA_HOME%\include\win32" -static-libgcc 
 * -static-libstdc++ -shared WindowsDirectory.cpp -o WindowsDirectory.dll
 *       </blockquote> 
 *       For 64-bit JREs, use mingw64, with the -m64 option. 
 *   <li>Put WindowsDirectory.dll into some directory in your windows PATH
 *   <li>Open indexes with WindowsDirectory and use it.
 * </p>
 * @lucene.experimental
 */
public class WindowsDirectory extends FSDirectory {
  private static final int DEFAULT_BUFFERSIZE = 4096; /* default pgsize on ia32/amd64 */
  
  static {
    System.loadLibrary("WindowsDirectory");
  }
  
  /** Create a new WindowsDirectory for the named location.
   * 
   * @param path the path of the directory
   * @param lockFactory the lock factory to use, or null for the default
   * ({@link NativeFSLockFactory});
   * @throws IOException
   */
  public WindowsDirectory(File path, LockFactory lockFactory) throws IOException {
    super(path, lockFactory);
  }

  /** Create a new WindowsDirectory for the named location and {@link NativeFSLockFactory}.
   *
   * @param path the path of the directory
   * @throws IOException
   */
  public WindowsDirectory(File path) throws IOException {
    super(path, null);
  }

  @Override
  public IndexInput openInput(String name, int bufferSize) throws IOException {
    ensureOpen();
    return new WindowsIndexInput(new File(getDirectory(), name), Math.max(bufferSize, DEFAULT_BUFFERSIZE));
  }
  
  protected static class WindowsIndexInput extends BufferedIndexInput {
    private final long fd;
    private final long length;
    boolean isClone;
    boolean isOpen;
    
    public WindowsIndexInput(File file, int bufferSize) throws IOException {
      super(bufferSize);
      fd = WindowsDirectory.open(file.getPath());
      length = WindowsDirectory.length(fd);
      isOpen = true;
    }
    
    @Override
    protected void readInternal(byte[] b, int offset, int length) throws IOException {
      if (WindowsDirectory.read(fd, b, offset, length, getFilePointer()) != length)
        throw new IOException("Read past EOF");
    }

    @Override
    protected void seekInternal(long pos) throws IOException {
    }

    @Override
    public synchronized void close() throws IOException {
      // NOTE: we synchronize and track "isOpen" because Lucene sometimes closes IIs twice!
      if (!isClone && isOpen) {
        WindowsDirectory.close(fd);
        isOpen = false;
      }
    }

    @Override
    public long length() {
      return length;
    }
    
    @Override
    public Object clone() {
      WindowsIndexInput clone = (WindowsIndexInput)super.clone();
      clone.isClone = true;
      return clone;
    }
  }
  
  /** Opens a handle to a file. */
  private static native long open(String filename) throws IOException;
  
  /** Reads data from a file at pos into bytes */
  private static native int read(long fd, byte bytes[], int offset, int length, long pos) throws IOException;
  
  /** Closes a handle to a file */
  private static native void close(long fd) throws IOException;
  
  /** Returns the length of a file */
  private static native long length(long fd) throws IOException;
}