asp.net中ashx生成验证码代码放在Linux(centos)主机上访问时无法显示问题

浏览数：27 / 时间：2015年06月09日

最近有个项目加入了验证码功能，就从自己博客以前的代码中找到直接使用，直接访问验证码页面报错如下：

Application Exception
System.ArgumentException
The requested FontFamily could not be found [GDI+ status: FontFamilyNotFound]

Description: HTTP 500.Error processing request.
Details: Non-web exception. Exception origin (name of application or object): System.Drawing.
Exception stack trace:
  at System.Drawing.GDIPlus.CheckStatus (Status status) [0x00000] in <filename unknown>:0 
  at System.Drawing.FontFamily..ctor (GenericFontFamilies genericFamily) [0x00000] in <filename unknown>:0 
  at (wrapper remoting-invoke-with-check) System.Drawing.FontFamily:.ctor (System.Drawing.Text.GenericFontFamilies)
  at System.Drawing.FontFamily.get_GenericMonospace () [0x00000] in <filename unknown>:0 
  at EnterpriseShow.UI.Manager.AjaxHandle.ValidCode.ProcessRequest (System.Web.HttpContext context) [0x00000] in <filename unknown>:0 
  at System.Web.HttpApplication+<Pipeline>c__Iterator1.MoveNext () [0x00000] in <filename unknown>:0 
  at System.Web.HttpApplication.Tick () [0x00000] in <filename unknown>:0

1、首先从window上copy字体安装到centos中

安装字体方法如下：本段文字来自唧唧的博客

在CentOS中安装中文字体
作者：唧唧
1、先从你本机 C:\Windows\Fonts 拷贝或者网络上下载你想要安装的字体文件（*.ttf文件）到 /usr/share/fonts/chinese/TrueType 目录下（如果系统中没有此目录，则自行mkdir创建，亦可重命名为自己喜欢的文件夹名）
2、修改字体文件的权限，使root用户以外的用户也可以使用
# cd /usr/share/fonts/chinese/TrueType
# chmod 755 *.ttf
3、建立字体缓存
# mkfontscale （如果提示 mkfontscale: command not found，需自行安装 # yum install mkfontscale ）
# mkfontdir 
# fc-cache -fv （如果提示 fc-cache: command not found，则需要安装# yum install fontconfig ）
4、重启计算机
# reboot

2、安装完毕后，我们在代码中指定要使用的字体

context.Response.ContentType = "image/gif";
            Bitmap basemap = new Bitmap(200, 60);
            Graphics garph1 = Graphics.FromImage(basemap);

            garph1.FillRectangle(new SolidBrush(Color.White), 0, 0, 200, 60);
            Font font = new Font("consola.ttf", 48, FontStyle.Bold, GraphicsUnit.Pixel);

            Random r = new Random();
            string letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ";
            string letter;
            StringBuilder s = new StringBuilder();
            for (int i = 0; i < 5; i++)
            {
                letter = letters.Substring(r.Next(0, letters.Length - 1), 1);
                s.Append(letter);
                garph1.DrawString(letter, font, new SolidBrush(Color.Black), i * 38, r.Next(0, 15));

            }

            Pen linePen = new Pen(new SolidBrush(Color.Black), 2);
            for (int x = 0; x < 6; x++)
            {
                garph1.DrawLine(linePen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));
            }

            basemap.Save(context.Response.OutputStream, ImageFormat.Gif);
            context.Session["CheckCode"] = s.ToString();    //存入Session，用于对比验证
            context.Response.End();