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Java example source code file (MappedByteBufferDataSource.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

datasource, illegalargumentexception, ioexception, mappedbytebuffer, mappedbytebufferdatasource, nio

The MappedByteBufferDataSource.java Java example source code

/*
 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

package sun.jvm.hotspot.debugger;

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

/** Implementation of DataSource using MappedByteBuffer. This works
    around a performance problem in JDK 1.4 where ByteBuffer's
    operations always become virtual calls rather than being inlined.
    Need to fix this soon. */

public class MappedByteBufferDataSource implements DataSource {
  private MappedByteBuffer buf;

  public MappedByteBufferDataSource(MappedByteBuffer buf) {
    this.buf = buf;
  }

  public byte  readByte()       throws IOException { return buf.get();            }
  public short readShort()      throws IOException { return buf.getShort();       }
  public int   readInt()        throws IOException { return buf.getInt();         }
  public long  readLong()       throws IOException { return buf.getLong();        }
  public int   read(byte[] b)   throws IOException { buf.get(b); return b.length; }
  public void  seek(long pos)   throws IOException {
    try {
      buf.position((int) pos);
    } catch (IllegalArgumentException e) {
      System.err.println("Error seeking to file position 0x" + Long.toHexString(pos));
      throw(e);
    }
  }
  public long  getFilePointer() throws IOException { return buf.position();       }
  public void  close()          throws IOException { buf = null;                  }
}

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