读取bmp图片数据

public  void getBMPImage(String source) throws Exception {

         clearNData();                        //清除数据保存区
         FileInputStream fs = null;

        try {
            fs = new FileInputStream(source);
            int bfLen = 14;
            byte bf[] = new byte[bfLen];
            fs.read(bf, 0, bfLen); // 读取14字节BMP文件头
            int biLen = 40;
            byte bi[] = new byte[biLen];
            fs.read(bi, 0, biLen); // 读取40字节BMP信息头
            // 源图宽度
            nWidth = (((int) bi[7] & 0xff) << 24)
                    | (((int) bi[6] & 0xff) << 16)
                    | (((int) bi[5] & 0xff) << 8) | (int) bi[4] & 0xff;
            // 源图高度
            nHeight = (((int) bi[11] & 0xff) << 24)
                    | (((int) bi[10] & 0xff) << 16)
                    | (((int) bi[9] & 0xff) << 8) | (int) bi[8] & 0xff;
            // 位数
            nBitCount = (((int) bi[15] & 0xff) << 8) | (int) bi[14] & 0xff;
            // 源图大小
            int nSizeImage = (((int) bi[23] & 0xff) << 24)
                    | (((int) bi[22] & 0xff) << 16)
                    | (((int) bi[21] & 0xff) << 8) | (int) bi[20] & 0xff;
            // 对24位BMP进行解析
            if (nBitCount == 24){
                int nPad = (nSizeImage / nHeight) - nWidth * 3;
                nData = new int[nHeight * nWidth];
                nB=new int[nHeight * nWidth];
                nR=new int[nHeight * nWidth];
                nG=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;                      
                        nB[nWidth * (nHeight - j - 1) + i]=(int) bRGB[nIndex]& 0xff;
                        nG[nWidth * (nHeight - j - 1) + i]=(int) bRGB[nIndex+1]& 0xff;
                        nR[nWidth * (nHeight - j - 1) + i]=(int) bRGB[nIndex+2]& 0xff;
                        nIndex += 3;
                    }
                    nIndex += nPad;
                }
 //               Toolkit kit = Toolkit.getDefaultToolkit();
 //               image = kit.createImage(new MemoryImageSource(nWidth, nHeight,
 //                       nData, 0, nWidth));
/*               
//调试数据的读取
                FileWriter fw = new FileWriter("C:\Documents and Settings\Administrator\My Documents\nDataRaw.txt");//创建新文件
                PrintWriter out = new PrintWriter(fw);
                for(int j=0;j<nHeight;j++){
                 for(int i=0;i<nWidth;i++){
                  out.print((65536*256+nData[nWidth * (nHeight - j - 1) + i])+"_"
                    +nR[nWidth * (nHeight - j - 1) + i]+"_"
                    +nG[nWidth * (nHeight - j - 1) + i]+"_"
                    +nB[nWidth * (nHeight - j - 1) + i]+" ");

                 }
                 out.println("");
                }
                out.close();
*/          
            }
        }
        catch (Exception e) {
            e.printStackTrace();
            throw new Exception(e);
        } 
        finally {
            if (fs != null) {
                fs.close();
            }
        }
     //   return image;
    }