bmploader.java

java程序

// 
// This code was taken and cleaned up from a 
// Javaworld tips and tricks column 
// 
import java.awt.image.*; 
import java.awt.*; 
import java.io.*; 
import javax.swing.*; 

// 
// really just a collection of methods to read a BMP file 
// 
public class BMPLoader 
{ 

    // build an int from a byte array - convert little to big endian 
    public static int constructInt(byte[] in,int offset) { 
        int ret =          ((int)in[offset + 3] & 0xff); 
        ret = (ret << 8) | ((int)in[offset + 2] & 0xff); 
        ret = (ret << 8) | ((int)in[offset + 1] & 0xff); 
        ret = (ret << 8) | ((int)in[offset + 0] & 0xff); 
        return(ret); 
    } 
    // build an int from a byte array - convert little to big endian 
    // set high order bytes to 0xfff 
    public static int constructInt3(byte[] in,int offset) { 
        int ret =            0xff; 
        ret = (ret << 8) | ((int)in[offset + 2] & 0xff); 
        ret = (ret << 8) | ((int)in[offset + 1] & 0xff); 
        ret = (ret << 8) | ((int)in[offset + 0] & 0xff); 
        return(ret); 
    } 

    // build an int from a byte array - convert little to big endian 
    public static long constructLong(byte[] in,int offset) { 
        long ret =          ((long)in[offset + 7] & 0xff); 
        ret |= (ret << 8) | ((long)in[offset + 6] & 0xff); 
        ret |= (ret << 8) | ((long)in[offset + 5] & 0xff); 
        ret |= (ret << 8) | ((long)in[offset + 4] & 0xff); 
        ret |= (ret << 8) | ((long)in[offset + 3] & 0xff); 
        ret |= (ret << 8) | ((long)in[offset + 2] & 0xff); 
        ret |= (ret << 8) | ((long)in[offset + 1] & 0xff); 
        ret |= (ret << 8) | ((long)in[offset + 0] & 0xff); 
        return(ret); 
    } 
  

    // build an double from a byte array - convert little to big endian 
    public static double constructDouble(byte[] in,int offset) { 
        long ret = constructLong(in,offset); 
        return(Double.longBitsToDouble(ret)); 
    } 

    // build an short from a byte array - convert little to big endian 
    public static short constructShort(byte[] in,int offset) { 
        short ret =        (short)((short)in[offset + 1] & 0xff); 
        ret = (short)((ret << 8) | (short)((short)in[offset + 0] & 0xff)); 
        return(ret); 
    } 

    // 
    // internal class representing a bitmap header structure 
    // with code to read it from a file 
    static class BitmapHeader { 
        public int nsize; 
        public int nbisize; 
        public int nwidth; 
        public int nheight; 
        public int nplanes; 
        public int nbitcount; 
        public int ncompression; 
        public int nsizeimage; 
        public int nxpm; 
        public int nypm; 
        public int nclrused; 
        public int nclrimp; 

        // read in the bitmap header 
        public void read(FileInputStream fs) throws IOException 
        { 
            final int bflen=14;  // 14 byte BITMAPFILEHEADER 
            byte bf[]=new byte[bflen]; 
            fs.read(bf,0,bflen); 
            final int bilen=40; // 40-byte BITMAPINFOHEADER 
            byte bi[]=new byte[bilen]; 
            fs.read(bi,0,bilen); 

            // Interperet data. 
            nsize = constructInt(bf,2); 
           //  System.out.println("File type is :"+(char)bf[0]+(char)bf[1]); 
          //  System.out.println("Size of file is :"+nsize); 

            nbisize = constructInt(bi,2); 
         //   System.out.println("Size of bitmapinfoheader is :"+nbisize); 

            nwidth = constructInt(bi,4); 
         //   System.out.println("Width is :"+nwidth); 

            nheight = constructInt(bi,8); 
          //  System.out.println("Height is :"+nheight); 

             nplanes = constructShort(bi,12); //(((int)bi[13]&0xff)<<8) | (int)bi[12]&0xff; 
          //  System.out.println("Planes is :"+nplanes); 

             nbitcount = constructShort(bi,14); //(((int)bi[15]&0xff)<<8) | (int)bi[14]&0xff; 
          //  System.out.println("BitCount is :"+nbitcount); 

            // Look for non-zero values to indicate compression 
             ncompression = constructInt(bi,16); 
          //  System.out.println("Compression is :"+ncompression); 

             nsizeimage = constructInt(bi,20); 
          //  System.out.println("SizeImage is :"+nsizeimage); 

             nxpm = constructInt(bi,24); 
           // System.out.println("X-Pixels per meter is :"+nxpm); 

             nypm = constructInt(bi,28); 
           // System.out.println("Y-Pixels per meter is :"+nypm); 

             nclrused = constructInt(bi,32); 
          //  System.out.println("Colors used are :"+nclrused); 

             nclrimp = constructInt(bi,36); 
          //  System.out.println("Colors important are :"+nclrimp); 
        } 
    } 

  public static Image read(FileInputStream fs) 
  { 
         try { 
            BitmapHeader bh = new BitmapHeader(); 
            bh.read(fs); 

            if (bh.nbitcount==24) 
                return(readMap24(fs,bh)); 

            if (bh.nbitcount==32) 
                return(readMap32(fs,bh)); 

            if (bh.nbitcount==8) 
                return(readMap8(fs,bh)); 

            fs.close(); 
        } 
        catch (IOException e) 
        { 
          // System.out.println("Caught exception in loadbitmap!"); 
        } 
        return(null); 
    } 
    /** 
        readMap24 internal routine to read the bytes in a 24 bit bitmap 

        Arguments: 
           fs - file stream 
           bh - header struct 
        Returns: 
            Image Object, be sure to check for (Image)null !!!! 

    */ 

  protected static Image readMap32(FileInputStream fs,BitmapHeader bh) throws IOException 
  { 
        Image image; 
          // No Palatte data for 24-bit format but scan lines are 
        // padded out to even 4-byte boundaries. 
        int xwidth = bh.nsizeimage / bh.nheight;
        int ndata[] = new int [bh.nheight * bh.nwidth]; 
        byte brgb[] = new byte [ bh.nwidth * 4 * bh.nheight]; 
        fs.read (brgb, 0, bh.nwidth  * 4 * bh.nheight); 
        int nindex = 0; 
        for (int j = 0; j < bh.nheight; j++) 
            { 
            for (int i = 0; i < bh.nwidth; i++) 
                { 
                ndata [bh.nwidth * (bh.nheight - j - 1) + i] = constructInt3(brgb,nindex); 
                 nindex += 4; 
                } 
            } 

        image = Toolkit.getDefaultToolkit().createImage 
            ( new MemoryImageSource (bh.nwidth, bh.nheight, 
                                     ndata, 0, bh.nwidth)); 
        fs.close(); 
        return(image); 
    } 

    /** 
        readMap24 internal routine to read the bytes in a 24 bit bitmap 

        Arguments: 
           fs - file stream 
           bh - header struct 
        Returns: 
            Image Object, be sure to check for (Image)null !!!! 

    */ 

  protected static Image readMap24(FileInputStream fs,BitmapHeader bh) throws IOException 
  { 
        Image image; 
          // No Palatte data for 24-bit format but scan lines are 
        // padded out to even 4-byte boundaries. 
        int npad = (bh.nsizeimage / bh.nheight) - bh.nwidth * 3; 
        int ndata[] = new int [bh.nheight * bh.nwidth]; 
        byte brgb[] = new byte [( bh.nwidth + npad) * 3 * bh.nheight]; 
        fs.read (brgb, 0, (bh.nwidth + npad) * 3 * bh.nheight); 
        int nindex = 0; 
        for (int j = 0; j < bh.nheight; j++) 
            { 
            for (int i = 0; i < bh.nwidth; i++) 
                { 
                ndata [bh.nwidth * (bh.nheight - j - 1) + i] = constructInt3(brgb,nindex); 
                nindex += 3; 
                } 
            nindex += npad; 
            } 

        image = Toolkit.getDefaultToolkit().createImage 
            ( new MemoryImageSource (bh.nwidth, bh.nheight, 
                                     ndata, 0, bh.nwidth)); 
        fs.close(); 
        return(image); 
    } 
      /** 
        readMap8 internal routine to read the bytes in a 8 bit bitmap 

        Arguments: 
           fs - file stream 
           bh - header struct 
        Returns: 
            Image Object, be sure to check for (Image)null !!!! 

    */ 
    protected static Image readMap8(FileInputStream fs,BitmapHeader bh) throws IOException 
      { 
        Image image; 

                // 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 (bh.nclrused > 0) 
                    { 
                    nNumColors = bh.nclrused; 
                    } 
                else 
                    { 
                    nNumColors = (1&0xff)<< bh.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 (bh.nsizeimage == 0) 
                    { 
                    bh.nsizeimage = ((((bh.nwidth* bh.nbitcount)+31) & ~31 ) >> 3); 
                    bh.nsizeimage *= bh.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] = constructInt3(bpalette,nindex8); 
                    nindex8 += 4; 
                    } 

                // Read the image data (actually indices into the palette) 
                // Scan lines are still padded out to even 4-byte 
                // boundaries. 
                int npad8 = (bh.nsizeimage / bh.nheight) - bh.nwidth; 
            //    System.out.println("nPad is:"+npad8); 

                int  ndata8[] = new int [bh.nwidth * bh.nheight]; 
                byte bdata[] = new byte [(bh.nwidth+npad8)* bh.nheight]; 
                fs.read (bdata, 0, (bh.nwidth+npad8)*bh.nheight); 
                nindex8 = 0; 
                for (int j8 = 0; j8 < bh.nheight; j8++) 
                    { 
                    for (int i8 = 0; i8 < bh.nwidth; i8++) 
                        { 
                        ndata8 [bh.nwidth*(bh.nheight-j8-1)+i8] = 
                            npalette [((int)bdata[nindex8]&0xff)]; 
                        nindex8++; 
                        } 
                    nindex8 += npad8; 
                    } 

                image = Toolkit.getDefaultToolkit().createImage 
                    ( new MemoryImageSource (bh.nwidth, bh.nheight, 
                                             ndata8, 0, bh.nwidth)); 

            return(image); 
         } 

    /** 
        load method - see read for details 

        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 static Image  load(String sdir, String sfile) { 
  return(load(sdir + sfile)); 
 } 
  

     /** 
        load method - see read for details 

        Arguments: 
            sdir - full path name 

        Returns: 
            Image Object, be sure to check for (Image)null !!!! 

    */ 
    public static Image  load(String sdir) 
 { 
        try 
        { 
            FileInputStream fs=new FileInputStream(sdir); 
            return(read(fs)); 
  } 
  catch(IOException ex) { 
   return(null); 
  } 
 } 

public static void main(String[] args) throws IOException
{
    if(args.length == 0){
        System.out.println("Usage >java BMPLoader ImageFile.bmp");
        System.exit(0);
    }
    FileInputStream in = new FileInputStream(args[0]);
    Image TheImage = read(in);
    JFrame TheFrame = new JFrame(args[0]);
    JLabel TheLabel = new JLabel(new ImageIcon(TheImage));
    TheFrame.getContentPane().add(new JScrollPane(TheLabel));
    TheFrame.setSize(300,300);
    TheFrame.setVisible(true);
}
        
// end class BMPLoader 
}