C#发送带图片邮件

C#有专门用于邮件发送的类MailMessage，在设置邮件正文为html类型后可以发送带图片的邮件
图片有两种附带方式

1. 使用base64编码
   将图片转化为base64的形式放在img标签的src里，这种方式有一个弊端，正文数据量太大，字符串太长了，如果有多张图片，正文长度会让人崩溃的，速度也会特别慢，因为我的服务器特别烂，不知道是电脑原因还是自己代码原因，在代码生成base64然后替换图片路径的时候，会卡好久

2. 附件图片，然后通过设置ID引用
   MailMessage自带了添加附件的类LinkedResource，在设置AlternateView为MediaTypeNames.Text.Html后，添加LinkedResource实例，然后正文图片的src设置地址为cid:ID即可引用附件里的图片，下面为代码

    /// 
   
    /// C#发送邮件函数
    /// 
    /// 发送者邮箱
    /// 发送人
    /// 接受者邮箱
    /// 收件人
    /// 主题
    /// 内容
    /// 附件
    /// smtp服务器
    /// 邮箱
    /// 密码
    /// 
    public bool ExecSend(string sfrom, string sfromer, string password, string sto, string stoer, string sSubject, string sBody, string sfile)
    {
        MailMessage oMail = new MailMessage();
        oMail.From = new MailAddress(sfrom, sfromer);
        string[] list = sto.Split(','); //多个收件人 ,隔开
        list = RemoveDuplicateString(list); //去除重复的收件人
        foreach (var item in list)
        {
            oMail.To.Add(item);
        }
        //// 添加附件
        if (sfile != "")
        {
            string[] Files = sfile.Split(new char[] { '$' }, StringSplitOptions.RemoveEmptyEntries);
            for (int i = 0; i < Files.Length; i++)
            {
                oMail.Attachments.Add(new Attachment(Files[i]));
            }
        }
        sBody = ReplaceImg(sBody, oMail);  // 处理图片
        oMail.Subject = sSubject;  //邮件标题
        oMail.Body = sBody;   //邮件内容
        oMail.IsBodyHtml = true;  //邮件格式
        oMail.BodyEncoding = Encoding.GetEncoding("GB2312");  //邮件采用的编码
        oMail.Priority = MailPriority.High;  //设置邮件的优先级为高
        SmtpClient client = new SmtpClient();  //发送邮件
        client.Host = "10.236.254.15";
        client.Credentials = new NetworkCredential(sfrom, password);
        client.DeliveryMethod = SmtpDeliveryMethod.Network;
        client.Port = 25;
        try
        {
            client.Send(oMail);
            return true;
        }
        catch (Exception e)
        {
            ILogs il = new LogsEx();
            il.AddLog("发送邮件失败:" + e.Message.ToString());
            return false;
        }
        finally
        {
            oMail.Dispose();  //释放资源
        }
    }
   
    /// 
   
    /// 去除重复项
    /// 
    /// 
    /// 
    private string[] RemoveDuplicateString(string[] items)
    {
        List ret = new List();
        for (int i = 0; i < items.Length; i++)
        {
            if (!ret.Contains(items[i]))
                ret.Add(items[i]);
        }
        return ret.ToArray();
    }
   
    /// 
   
    /// 处理邮件内容中的图片
    /// 将图片改为附件形式在body中显示
    /// 
    /// 
    /// 
    private string ReplaceImg(string body, MailMessage m)
    {
        try
        {
            Dictionary imgDic = new Dictionary();
            body = GetImgStrem(body, imgDic);
            AlternateView avHtml = AlternateView.CreateAlternateViewFromString(body, null, MediaTypeNames.Text.Html);
            if (imgDic.Count != 0) // 内容添加图片
            {
                foreach (var dic in imgDic)
                {
                    LinkedResource lrImage = new LinkedResource(dic.Value, "image/gif");
                    lrImage.ContentId = dic.Key;
                    avHtml.LinkedResources.Add(lrImage);
                }
            }
            m.AlternateViews.Add(avHtml);
            return body;
        }
        catch(Exception)
        {
            return body;
        }
    }
   
    private string GetImgStrem(string body, Dictionary imgDic)
    {
        string mactch;
        Regex reg = new Regex(@"(?i)]*?\ssrc\s*=\s*(['""]?)(?[^'""\s>]+)\1[^>]*>");
        MatchCollection mc = reg.Matches(body);
        for(int i = 0;i < mc.Count;i++)
        {
            string key = "pic" + i;
            mactch = mc[i].Groups["src"].Value;
            body = body.Replace(mactch, "cid:" + key);
            FileStream fs = new FileStream(mactch, FileMode.Open);
            imgDic.Add(key, fs);
        }
        return body;
    }