storableinputstream.java

实现数据库的storage manager 功能

/*
 * Copyright (c) 2000-2004, Rickard C鰏ter, Martin Svensson
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice, 
 * this list of conditions and the following disclaimer. 
 * Redistributions in binary form must reproduce the above copyright notice, 
 * this list of conditions and the following disclaimer in the documentation 
 * and/or other materials provided with the distribution. 
 * Neither the name of SICS nor the names of its contributors 
 * may be used to endorse or promote products derived from this software 
 * without specific prior written permission. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 *
 *
 */

package com.mellowtech.disc;

import java.io.*;
import java.nio.channels.*;

/**
* Reads ByteStorables from a given input stream. Iternally it uses
* a StorableReadChannel
*
* @author Martin Svensson
* @version 1.0
* @see StorableReadChannel
*/
public class StorableInputStream {

  private StorableReadChannel mChannel;
      
  /**
   * Initialize to read ByteStorables from a given input stream using
   * the specified template.
   *
   * @param is stream to read from
   * @param template a ByteStorable template
   * @exception IOException if an error occurs
   */
  public StorableInputStream(InputStream is, ByteStorable template) throws IOException{
    mChannel = new StorableReadChannel(Channels.newChannel(is),
				       template);
  }
  
  /**
   * Retrieve the next ByteStorable in the stream.
   *
   * @return the next object or null if there are no more to read.
   * @exception IOException if an error occurs
   */
  public ByteStorable next() throws IOException{
    return mChannel.next();
  }
  
}