Asp.net 绘图“参数无效”的错误

 下面的代码第二次运行报错

 public void ProcessRequest(HttpContext context)
{
        Bitmap nbitmap = new Bitmap(1000, 1000);
        Graphics g = Graphics.FromImage(nbitmap);
 
        Font font = new Font(FontFamily.GenericSansSerif, 10, FontStyle.Italic);
        Brush brush = Brushes.Black;
        g.DrawString("测试字符串", font, brush, 10, 10);/////运行到这句报参数无效
        g.Dispose();
        font.Dispose();
        brush.Dispose();
        nbitmap.Save(context.Server.MapPath("~/upload/cert" + DateTime.Now.ToString("yyyyMMddHHmmssfff") + ".jpg"));
        nbitmap.Dispose();
}

brush.Dispose();去掉这句，因为你引用的是Brushes.Black静态变量，Dispose后再次调用brush就null会出错