grails从数据库读取blob显示图片

来源：互联网发布：海康网络视频监控方案编辑：程序博客网时间：2024/05/27 20:59

前台：

后台：

def image = {
  if(params.id!=null){
   Connection conn = SqlCon.getCon();
   byte[] description = "";
   def query ="""select photo from photo_list where id = """+params.id+""" and record_state=0 """;
   def pstmt = conn.prepareStatement(query);
   ResultSet result = pstmt.executeQuery();
   StringBuffer myStringBuffer = new StringBuffer();
   if (result.next()) {
    java.sql.Blob blob = result.getBlob("photo");
    InputStream inStream = blob.getBinaryStream();
    long nLen = blob.length();
    int nSize = (int) nLen;
    description = new byte[nSize];
    inStream.read(description);
    inStream.close();

    description = ChangeImgSize(description, 200, 200);
    if(description!=null){
     OutputStream op = response.getOutputStream();
     op.write(description, 0, description.length);
     op.close();
     op = null;
    }
    response.flushBuffer();

   }
   result.close();
   pstmt.close();
   conn.close();
  }
}

private byte[] ChangeImgSize(byte[] data, int nw, int nh){
  byte[] newdata = null;
  try{
   BufferedImage bis = ImageIO.read(new ByteArrayInputStream(data));
   if(bis!=null){
    int w = bis.getWidth();
    int h = bis.getHeight();
    double sx = (double) nw / w;
    double sy = (double) nh / h;
    AffineTransform transform = new AffineTransform();
    transform.setToScale(sx, sy);
    //AffineTransformOp ato = new AffineTransformOp(transform, null);
    //原始颜色
    //BufferedImage bid = new BufferedImage(nw, nh, BufferedImage.TYPE_3BYTE_BGR);
    //ato.filter(bis, bid);
    //转换成byte字节
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageIO.write(bis, "jpeg", baos);
    newdata = baos.toByteArray();
   }
  }catch(IOException e){
   e.printStackTrace();
  }
  return newdata;
}