gov/nasa/worldwind/formats/nitfs/NitfsUtil.java

   1 package gov.nasa.worldwind.formats.nitfs;
   2
   3 import gov.nasa.worldwind.*;
   4
   5 import java.io.*;
   6 import java.nio.channels.*;
   7 import java.nio.*;
   8 /*
   9 Copyright (C) 2001, 2007 United States Government
  10 as represented by the Administrator of the
  11 National Aeronautics and Space Administration.
  12 All Rights Reserved.
  13 */
  14
  15 /**
  16  * @author Lado Garakanidze
  17  * @version $Id: NitfsUtil Mar 30, 2007 12:43:29 PM lado
  18  */
  19 public class NitfsUtil
  20 {
  21     public static String getString(java.nio.ByteBuffer buffer, int offset, int len)
  22     {
  23         String s = StringUtil.EMPTY;
  24         if (null != buffer && buffer.capacity() >= offset + len)
  25         {
  26             byte[] dest = new byte[len];
  27             buffer.position(offset);
  28             buffer.get(dest, 0, len);
  29             s = new String(dest).trim();
  30         }
  31         return s;
  32     }
  33
  34     public static String getString(java.nio.ByteBuffer buffer, int len)
  35     {
  36         String s = StringUtil.EMPTY;
  37         if (null != buffer && buffer.remaining() >= len)
  38         {
  39             byte[] dest = new byte[len];
  40             buffer.get(dest, 0, len);
  41             s = new String(dest).trim();
  42         }
  43         return s;
  44     }
  45
  46     public static int getNumeric(java.nio.ByteBuffer buffer, int len)
  47     {
  48         String s = StringUtil.EMPTY;
  49         if (null != buffer && buffer.remaining() >= len)
  50         {
  51             byte[] dest = new byte[len];
  52             buffer.get(dest, 0, len);
  53             s = new String(dest);
  54         }
  55         return Integer.parseInt(s);
  56     }
  57
  58     public static short getShortNumeric(java.nio.ByteBuffer buffer, int len)
  59     {
  60         String s = StringUtil.EMPTY;
  61         if (null != buffer && buffer.remaining() >= len)
  62         {
  63             byte[] dest = new byte[len];
  64             buffer.get(dest, 0, len);
  65             s = new String(dest);
  66         }
  67         return (short) (0xFFFF & Integer.parseInt(s));
  68     }
  69
  70     public static boolean getBoolean(java.nio.ByteBuffer buffer)
  71     {
  72         return !((byte) 0 == buffer.get()); // 0 = false, non-zero = true
  73     }
  74
  75     public static short getByteAsShort(java.nio.ByteBuffer buffer)
  76     {
  77         return (short) (0xFF & buffer.get());
  78     }
  79
  80     public static int getUShort(java.nio.ByteBuffer buffer)
  81     {
  82         return 0xFFFF & buffer.getShort();
  83     }
  84
  85     public static long getUInt(java.nio.ByteBuffer buffer)
  86     {
  87         return 0xFFFFFFFFL & (long) buffer.getInt();
  88     }
  89
  90     private static final int PAGE_SIZE = 4096;
  91
  92
  93     public static java.nio.ByteBuffer readEntireFile(java.io.File file) throws java.io.IOException
  94     {
  95         return NitfsUtil.memoryMapFile(file);
  96         // return NitfsUtil.readFile(file);
  97     }
  98
  99     private static java.nio.ByteBuffer readFile(java.io.File file) throws java.io.IOException
 100     {
 101         java.io.FileInputStream fis = new java.io.FileInputStream(file);
 102         java.nio.ByteBuffer buffer = java.nio.ByteBuffer.allocate(PAGE_SIZE);
 103         java.nio.channels.ReadableByteChannel channel = java.nio.channels.Channels.newChannel(fis);
 104
 105         int count = 0;
 106         while (count >= 0)
 107         {
 108             count = channel.read(buffer);
 109             if (count > 0 && !buffer.hasRemaining())
 110             {
 111                 java.nio.ByteBuffer biggerBuffer = java.nio.ByteBuffer.allocate(buffer.limit() + PAGE_SIZE);
 112                 biggerBuffer.put((java.nio.ByteBuffer) buffer.rewind());
 113                 buffer = biggerBuffer;
 114             }
 115         }
 116
 117         if (buffer != null)
 118             buffer.flip();
 119
 120         return buffer;
 121     }
 122
 123     private static java.nio.ByteBuffer memoryMapFile(java.io.File file) throws IOException
 124     {
 125         FileChannel roChannel = new RandomAccessFile(file, "r").getChannel();
 126         long fileSize = roChannel.size();
 127         MappedByteBuffer mapFile = roChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileSize);
 128         if (!mapFile.isLoaded())
 129             mapFile.load();
 130         roChannel.close();
 131         return mapFile;
 132     }
 133 }