Java 使用 NIO 方式读文件，javanio,FileHole.jav

Java 使用 NIO 方式读文件，javanio,FileHole.jav

FileHole.java

package com.ronsoft.books.nio.channels;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;import java.io.File;import java.io.RandomAccessFile;import java.io.IOException;/** * Create a file with holes in it. * * Created April 2002 * @author Ron Hitchens (ron@ronsoft.com) * @version $Id: FileHole.java,v 1.2 2002/05/19 04:55:45 ron Exp $ */public class FileHole{   public static void main (String [] argv)      throws IOException   {      // create a temp file, open for writing and get a FileChannel      File temp = File.createTempFile ("holy", null);      RandomAccessFile file = new RandomAccessFile (temp, "rw");      FileChannel channel = file.getChannel();      // create a working buffer      ByteBuffer byteBuffer = ByteBuffer.allocateDirect (100);      putData (0, byteBuffer, channel);      putData (5000000, byteBuffer, channel);      putData (50000, byteBuffer, channel);      // Size will report the largest position written, but      // there are two holes in this file.  This file will      // not consume 5MB on disk (unless the filesystem is      // extremely brain-damaged).      System.out.println ("Wrote temp file '" + temp.getPath()         + "', size=" + channel.size());      channel.close();      file.close();   }   private static void putData (int position, ByteBuffer buffer,      FileChannel channel)      throws IOException   {      String string = "*<-- location " + position;      buffer.clear();      buffer.put (string.getBytes ("US-ASCII"));      buffer.flip();      channel.position (position);      channel.write (buffer);   }}