JAVA读取BMP图片_以字节流读取BMP图像_从数据库读取图片

最近一直在搞图片上传这些问题、今天又找到一种新方法、记下来、方便以后使用

用字节流而不是用JAVA的API函数read()有助于大家理解理解BMP的存储方式哈

同时，如果是从数据库中读取图片的话，也是用字节流读取，需要自己进行转换的

所以这种方式更利于我们的使用、话不多说、直接为大家献上代码

public Image myRead(String path) throws java.io.IOException {
    Image image = null;  
    int biWidth,biHeight,bicount,biSizeImage,
	npad,head,information,size;
    try {
      FileInputStream fs = new FileInputStream(path);
      head = 14;
      /** 
       * head is 14bytes; 
       */
      byte header[] = new byte[head];
      fs.read(header, 0, head);
      information = 40;   
      /**
       * information is 40bytes;  
       */
      byte info[] = new byte[information];
      fs.read(info, 0, information);
       
      /**
       * get the wideth of the bmp 
       */
      biWidth = ((int)(info[7]&toDec))<<24 
          | ((int)(info[6]&toDec))<<16 
          | ((int)(info[5]&toDec)) << 8
          | ((int)(info[4]&toDec));
       
      /**
       *   get the heigth of the bmp
       */
      biHeight = ((int)(info[11]&toDec))<<24 
          | ((int)(info[10]&toDec))<<16 
          | ((int)(info[9]&toDec)) << 8
          | ((int)(info[8]&toDec));     
      bicount = (((int)info[15] & toDec) << 8) 
          | (int)info[14] & toDec; 
       
      /**
       * get the size of the image
       */
      biSizeImage = ((int)(info[23]&toDec))<<24 
          | ((int)(info[22]&toDec))<<16 
          | ((int)(info[21]&toDec)) << 8
          | ((int)(info[20]&toDec));
       
 
 
      if (bicount == 24) {
        /**
         *   compute the empty byte 
         */
        npad = (biSizeImage / biHeight) - biWidth*3;
        /**  
         * if the BitCount is 24, every pixel has 3  
         */
        if (npad ==4 ) {
          npad = 0;
        }
        /*  compute the size of pixel  */
        size = (biWidth + npad) * 3 *biHeight;
        byte alRgb[];
        if (npad != 0) {
          /**
           * creat a array to save RGB data
           */
          alRgb = new byte[(biWidth + npad) * 3 *biHeight];
        } else {
          /**
           * creat a array to save RGB data
           */
          alRgb = new byte[biSizeImage];
        }
         
        /*   read all rgb data  */
        fs.read(alRgb, 0 , size);
        int rgbData[] = new int[biHeight*biWidth];
         
        /*   translate hexadecimal data to decimal data   */
        int nindex = 0;
        for(int j = 0; j < biHeight; j++){  
          for(int i = 0; i < biWidth; i++){  
            rgbData[biWidth * (biHeight - j - 1) + i] =  
                (255 & 0xff) << 24  
                | (((int)alRgb[nindex + 2] & 0xff) << 16)  
                | (((int)alRgb[nindex + 1] & 0xff) << 8)  
                | (int)alRgb[nindex] & 0xff;  
            nindex += 3;  
          }  
          nindex += npad;  
        } 
        /*  creat image object */
        image = Toolkit.getDefaultToolkit().createImage(new MemoryImageSource(  
            biWidth, biHeight, rgbData, 0, biWidth));  
      }
      fs.close();  
    } catch (IOException e) {
      return null;
    }
    return image;  
  }
   
  public Image myWrite(Image image, String file ) 
				throws java.io.IOException {
    try {
      int w = image.getHeight(null);
      int h = image.getWidth(null);
      /**
       * ceate graphic
       */
      BufferedImage bi = new BufferedImage(w,h,BufferedImage.TYPE_3BYTE_BGR);
      Graphics g = bi.getGraphics();
      g.drawImage(image, 0, 0, null);
      /*  open file */
      File iFile= new File(file+".bmp");
      ImageIO.write(bi, "bmp", iFile);
      } catch (IOException e) {
        return null;
      }
     return image;
  }