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;
     }