很不幸，Java中没有类似struct的东西。
但是可以解析二进制格式，方法是将数据读进byte array然后手工计算。
样例：
/**
loadbitmap() method converted from Windows C code.
Reads only uncompressed 24- and 8-bit images. Tested with
images saved using Microsoft Paint in Windows 95. If the image
is not a 24- or 8-bit image, the program refuses to even try.
I guess one could include 4-bit images by masking the byte
by first 1100 and then 0011. I am not really
interested in such images. If a compressed image is attempted,
the routine will probably fail by generating an IOException.
Look for variable ncompression to be different from 0 to indicate
compression is present.
Arguments:
sdir and sfile are the result of the FileDialog()
getDirectory() and getFile() methods.
Returns:
Image Object, be sure to check for (Image)null !!!!
*/
public Image loadbitmap (String sdir, String sfile)
{
Image image;
System.out.println("loading:"+sdir+sfile);
try
{
FileInputStream fs=new FileInputStream(sdir+sfile);
int bflen=14; // 14 byte BITMAPFILEHEADER
byte bf[]=new byte[bflen];
fs.read(bf,0,bflen);
int bilen=40; // 40-byte BITMAPINFOHEADER
byte bi[]=new byte[bilen];
fs.read(bi,0,bilen);
// Interperet data.
int nsize = (((int)bf[5]&0xff)<<24)
| (((int)bf[4]&0xff)<<16)
| (((int)bf[3]&0xff)<<8)
| (int)bf[2]&0xff;
System.out.println("File type is :"+(char)bf[0]+(char)bf[1]);
System.out.println("Size of file is :"+nsize);
int nbisize = (((int)bi[3]&0xff)<<24)
| (((int)bi[2]&0xff)<<16)
| (((int)bi[1]&0xff)<<8)
| (int)bi[0]&0xff;
System.out.println("Size of bitmapinfoheader is :"+nbisize);
int nwidth = (((int)bi[7]&0xff)<<24)
| (((int)bi[6]&0xff)<<16)
| (((int)bi[5]&0xff)<<8)
| (int)bi[4]&0xff;
System.out.println("Width is :"+nwidth);
int nheight = (((int)bi[11]&0xff)<<24)
| (((int)bi[10]&0xff)<<16)
| (((int)bi[9]&0xff)<<8)
| (int)bi[8]&0xff;
System.out.println("Height is :"+nheight);
int nplanes = (((int)bi[13]&0xff)<<8) | (int)bi[12]&0xff;
System.out.println("Planes is :"+nplanes);
int nbitcount = (((int)bi[15]&0xff)<<8) | (int)bi[14]&0xff;
System.out.println("BitCount is :"+nbitcount);
// Look for non-zero values to indicate compression
int ncompression = (((int)bi[19])<<24)
| (((int)bi[18])<<16)
| (((int)bi[17])<<8)
| (int)bi[16];
System.out.println("Compression is :"+ncompression);
int nsizeimage = (((int)bi[23]&0xff)<<24)
| (((int)bi[22]&0xff)<<16)
| (((int)bi[21]&0xff)<<8)
| (int)bi[20]&0xff;
System.out.println("SizeImage is :"+nsizeimage);
int nxpm = (((int)bi[27]&0xff)<<24)
| (((int)bi[26]&0xff)<<16)
| (((int)bi[25]&0xff)<<8)
| (int)bi[24]&0xff;
System.out.println("X-Pixels per meter is :"+nxpm);
int nypm = (((int)bi[31]&0xff)<<24)
| (((int)bi[30]&0xff)<<16)
| (((int)bi[29]&0xff)<<8)
| (int)bi[28]&0xff;
System.out.println("Y-Pixels per meter is :"+nypm);
int nclrused = (((int)bi[35]&0xff)<<24)
| (((int)bi[34]&0xff)<<16)
| (((int)bi[33]&0xff)<<8)
| (int)bi[32]&0xff;
System.out.println("Colors used are :"+nclrused);
int nclrimp = (((int)bi[39]&0xff)<<24)
| (((int)bi[38]&0xff)<<16)
| (((int)bi[37]&0xff)<<8)
| (int)bi[36]&0xff;
System.out.println("Colors important are :"+nclrimp);
if (nbitcount==24)
{
// No Palatte data for 24-bit format but scan lines are
// padded out to even 4-byte boundaries.
int npad = (nsizeimage / nheight) - nwidth * 3;
int ndata[] = new int [nheight * nwidth];
byte brgb[] = new byte [( nwidth + npad) * 3 * nheight];
fs.read (brgb, 0, (nwidth + npad) * 3 * nheight);
int nindex = 0;
for (int j = 0; j < nheight; j++)
{
for (int i = 0; i < nwidth; i++)
{
ndata [nwidth * (nheight - j - 1) + i] =
(255&0xff)<<24
| (((int)brgb[nindex+2]&0xff)<<16)
| (((int)brgb[nindex+1]&0xff)<<8)
| (int)brgb[nindex]&0xff;
// System.out.println("Encoded Color at ("
+i+","+j+")is:"+nrgb+" (R,G,B)= ("
+((int)(brgb[2]) & 0xff)+","
+((int)brgb[1]&0xff)+","
+((int)brgb[0]&0xff)+")");
nindex += 3;
}
nindex += npad;
}
image = createImage
( new MemoryImageSource (nwidth, nheight,
ndata, 0, nwidth));
}
else if (nbitcount == 8)
{
// Have to determine the number of colors, the clrsused
// parameter is dominant if it is greater than zero. If
// zero, calculate colors based on bitsperpixel.
int nNumColors = 0;
if (nclrused > 0)
{
nNumColors = nclrused;
}
else
{
nNumColors = (1&0xff)<<nbitcount;
}
System.out.println("The number of Colors is"+nNumColors);
// Some bitmaps do not have the sizeimage field calculated
// Ferret out these cases and fix 'em.
if (nsizeimage == 0)
{
nsizeimage = ((((nwidth*nbitcount)+31) & 31 ) >> 3);
nsizeimage *= nheight;
System.out.println("nsizeimage (backup) is"+nsizeimage);
}
// Read the palatte colors.
int npalette[] = new int [nNumColors];
byte bpalette[] = new byte [nNumColors*4];
fs.read (bpalette, 0, nNumColors*4);
int nindex8 = 0;
for (int n = 0; n < nNumColors; n++)
{
npalette[n] = (255&0xff)<<24
| (((int)bpalette[nindex8+2]&0xff)<<16)
| (((int)bpalette[nindex8+1]&0xff)<<8)
| (int)bpalette[nindex8]&0xff;
// System.out.println ("Palette Color "+n
+" is:"+npalette[n]+" (res,R,G,B)= ("
+((int)(bpalette[nindex8+3]) & 0xff)+","
+((int)(bpalette[nindex8+2]) & 0xff)+","
+((int)bpalette[nindex8+1]&0xff)+","
+((int)bpalette[nindex8]&0xff)+")");
nindex8 += 4;
}
// Read the image data (actually indices into the palette)
// Scan lines are still padded out to even 4-byte
// boundaries.
int npad8 = (nsizeimage / nheight) - nwidth;
System.out.println("nPad is:"+npad8);
int ndata8[] = new int [nwidth*nheight];
byte bdata[] = new byte [(nwidth+npad8)*nheight];
fs.read (bdata, 0, (nwidth+npad8)*nheight);
nindex8 = 0;
for (int j8 = 0; j8 < nheight; j8++)
{
for (int i8 = 0; i8 < nwidth; i8++)
{
ndata8 [nwidth*(nheight-j8-1)+i8] =
npalette [((int)bdata[nindex8]&0xff)];
nindex8++;
}
nindex8 += npad8;
}
image = createImage
( new MemoryImageSource (nwidth, nheight,
ndata8, 0, nwidth));
}
else
{
System.out.println ("Not a 24-bit or 8-bit Windows Bitmap, aborting...");
image = (Image)null;
}
fs.close();
return image;
}
catch (Exception e)
{
System.out.println("Caught exception in loadbitmap!");
}
return (Image) null;
}
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