C# 发送电子邮件mvc 5时奇怪的异步或非异步控制器操作行为

我在控制器中有一个异步操作，如下所示

public async Task<ActionResult> Register(MerchantRegistrationViewModel merchantRegistrationViewModel)
{
    if (ModelState.IsValid)
    {
        //Some code

        //SendMail
        EmailManager em = new EmailManager("MerchantVerify.htm",merchant,"Verify Email");
        await em.SendEmailAsync();


        db.Merchants.Add(merchant);
        await db.SaveChangesAsync();
        return RedirectToAction("Success");

    }          
}

我注意到的问题是包含此代码块的方法

GetEmailTemplate（）

private void GetEmailTemplate()
{
    //Tried Option 1
    //mailBody = System.IO.File.ReadAllText(HostingEnvironment.MapPath("/Content/MailText/" + mailTemplate));

    //Tried Option 2 
    using (FileStream fs = new FileStream(HostingEnvironment.MapPath("/Content/MailText/" + mailTemplate), FileMode.Open))
    using (StreamReader sr = new StreamReader(fs))
    {
        mailBody = sr.ReadToEnd(); 
    }

}

如果我对此代码块进行注释，并将操作更改为异步或非异步，则会发送电子邮件。如果我取消注释任何选项，邮件将永远不会收到。我没有发现任何错误

我怀疑这与我读取模板文件的方式有关

public class EmailManager
{
    private string mailTemplate;
    private Merchant merchant;
    private string mailBody = string.Empty;
    private string subject;

    public EmailManager()
    {

    }

    public EmailManager(string mailTemplate, Merchant merchant, string subject)
    {
        this.mailTemplate = mailTemplate;
        this.merchant = merchant;
        this.subject = subject;
    }

    private void GetEmailTemplate()
    {
        //Get Mail Text Path
        //mailBody = System.IO.File.ReadAllText(HostingEnvironment.MapPath("/Content/MailText/" + mailTemplate));
        using (FileStream fs = new FileStream(HostingEnvironment.MapPath("/Content/MailText/" + mailTemplate),FileMode.Open ,FileAccess.Read, FileShare.Read))
        using (StreamReader sr = new StreamReader(fs))
        {
            mailBody = sr.ReadToEnd(); // 1
        }           
    }


    private string BuildEmailBodyForVerifyMerchant()
    {
        //Replace Custom Variables for Email Body
        Uri url = System.Web.HttpContext.Current.Request.Url;
        string UrlLink = url.OriginalString.Replace(url.PathAndQuery, "");
        merchant.ProviderUserKey = Guid.NewGuid().ToString();
        UrlLink = String.Concat(UrlLink, "/");
        var verifyUrl = UrlLink + "business/verify/" + merchant.ProviderUserKey.ToString();

        //replace variables 
        mailBody = mailBody.Replace("~userLastName~", merchant.Name);
        mailBody = mailBody.Replace("~name~", String.Format("{0} {1}", merchant.FirstName, merchant.LastName));
        mailBody = mailBody.Replace("~companyName~", merchant.Name);
        mailBody = mailBody.Replace("~dateOfRegistration~", merchant.DateOfRegistration.Value.ToShortDateString());
        mailBody = mailBody.Replace("~verifyUrl~", verifyUrl);
        mailBody = mailBody.Replace("~email~", merchant.Email);

        return mailBody;
    }

    private MailMessage BuildEmailMessage(string body, string subject)
    {
        MailMessage msg = new MailMessage();

        msg.From = new MailAddress("no-reply@mydomain.com");
        msg.To.Add(new MailAddress(merchant.Email.ToString()));           
        msg.Subject = subject;
        msg.Body = body;

        return msg;
    }


    public async Task SendEmailAsync()
    {
        GetEmailTemplate();

        var emailBody = BuildEmailBodyForVerifyMerchant();

        var emailToSend = BuildEmailMessage(emailBody, subject);

        var client = new SmtpClient();
        await client.SendMailAsync(emailToSend);
    }


}

---

下面是一个重构的

EmailManager

，给出了OP中提供的示例。 对这些方法进行了重构，以更好地表达它们的依赖关系，并希望有助于隔离

GetEmailTemplate

方法中可能导致问题的原因

public interface IEmailManager {
    Task SendEmailAsync();
}

public class EmailManager : IEmailManager {
    private string mailTemplate;
    private Merchant merchant;
    private string subject;

    public EmailManager(string mailTemplate, Merchant merchant, string subject) {
        this.mailTemplate = mailTemplate;
        this.merchant = merchant;
        this.subject = subject;
    }

    private async Task<string> GetEmailTemplateAsync(string mailTemplate) {
        var mailBody = String.Empty;
        //Get Mail Text Path
        var path = HostingEnvironment.MapPath("/Content/MailText/" + mailTemplate);

        //mailBody = System.IO.File.ReadAllText(HostingEnvironment.MapPath("/Content/MailText/" + mailTemplate));
        using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
        using (var sr = new StreamReader(fs)) {
            mailBody = await sr.ReadToEndAsync();
        }

        return mailBody;
    }


    private string BuildVerifyEmailBodyForMerchant(string mailBody, Merchant merchant) {
        //Replace Custom Variables for Email Body
        var url = System.Web.HttpContext.Current.Request.Url;
        var urlLink = url.OriginalString.Replace(url.PathAndQuery, "");
        merchant.ProviderUserKey = Guid.NewGuid().ToString();
        urlLink = String.Concat(urlLink, "/");
        var verifyUrl = urlLink + "business/verify/" + merchant.ProviderUserKey.ToString();

        //replace variables 
        mailBody = mailBody.Replace("~userLastName~", merchant.Name);
        mailBody = mailBody.Replace("~name~", String.Format("{0} {1}", merchant.FirstName, merchant.LastName));
        mailBody = mailBody.Replace("~companyName~", merchant.Name);
        mailBody = mailBody.Replace("~dateOfRegistration~", merchant.DateOfRegistration.Value.ToShortDateString());
        mailBody = mailBody.Replace("~verifyUrl~", verifyUrl);
        mailBody = mailBody.Replace("~email~", merchant.Email);

        return mailBody;
    }

    private MailMessage BuildEmailMessage(string body, string subject, Merchant merchant) {
        var msg = new MailMessage();

        msg.From = new MailAddress("no-reply@mydomain.com");
        msg.To.Add(merchant.Email.ToString());
        msg.Subject = subject;
        msg.Body = body;

        return msg;
    }

    public async Task SendEmailAsync() {
        var emailTemplate = await GetEmailTemplateAsync(mailTemplate);

        var emailBody = BuildVerifyEmailBodyForMerchant(emailTemplate, merchant);

        var emailToSend = BuildEmailMessage(emailBody, subject, merchant);

        using (var client = new SmtpClient()) {
            await client.SendMailAsync(emailToSend);
        }
    }
}

公共接口IEmailManager{
任务SendEmailAsync（）；
}
公共类EmailManager:IEmailManager{
私有字符串邮件模板；
私人商人；
私有字符串主题；
public EmailManager（字符串邮件模板、商户、字符串主题）{
this.mailTemplate=mailTemplate；
this.merchant=商户；
this.subject=主语；
}
专用异步任务GetEmailTemplateAsync（字符串mailTemplate）{
var mailBody=String.Empty；
//获取邮件文本路径
var path=HostingEnvironment.MapPath（“/Content/MailText/”+mailTemplate）；
//mailBody=System.IO.File.ReadAllText（HostingEnvironment.MapPath（“/Content/MailText/”+mailTemplate））；
使用（var fs=new FileStream（路径，FileMode.Open，FileAccess.Read，FileShare.Read））
使用（var sr=新的StreamReader（fs））{
mailBody=wait sr.ReadToEndAsync（）；
}
返回邮件体；
}
私有字符串BuildVerifyEmailBodyForMerchant（字符串邮箱，商户）{
//替换电子邮件正文的自定义变量
var url=System.Web.HttpContext.Current.Request.url；
var urlink=url.OriginalString.Replace（url.PathAndQuery，“”）；
merchant.ProviderUserKey=Guid.NewGuid（）.ToString（）；
urlink=String.Concat（urlink，“/”）；
var verifyUrl=urlink+“business/verify/”+merchant.ProviderUserKey.ToString（）；
//替换变量
mailBody=mailBody.Replace（“~userLastName~”，merchant.Name）；
mailBody=mailBody.Replace（“~name~”，String.Format（“{0}{1}”，merchant.FirstName，merchant.LastName））；
mailBody=mailBody.Replace（“~companyName~”，merchant.Name）；
mailBody=mailBody.Replace（“~dateOfRegistration~”，merchant.dateOfRegistration.Value.ToShortDateString（））；
mailBody=mailBody.Replace（“~verifyUrl~”，verifyUrl）；
mailBody=mailBody.Replace（“~email~”，merchant.email）；
返回邮件体；
}
private MailMessage BuildEmailMessage（字符串正文、字符串主题、商户）{
var msg=new MailMessage（）；
msg.From=新邮件地址（“否-reply@mydomain.com");
msg.To.Add（merchant.Email.ToString（））；
msg.Subject=主语；
msg.Body=Body；
返回味精；
}
公共异步任务SendEmailAsync（）{
var emailTemplate=await GetEmailTemplateAsync（mailTemplate）；
var emailBody=BuildVerifyEmailBodyForMerchant（emailTemplate，商户）；
var emailToSend=BuildEmailMessage（emailBody、主题、商户）；
使用（var client=new SmtpClient（））{
等待client.SendMailAsync（emailToSend）；
}
}
}

有什么变化吗？你的措辞有点混乱（无论如何对我来说），所以我要说清楚-你是说如果你注释掉

GetEmailTemplate（）行，邮件发送，如果不发送，则不发送？@sellotape该行或该方法中的代码。@GSerg正在尝试建议的链接。@GSerg未更改任何内容：(
public interface IEmailManager {
    Task SendEmailAsync();
}

public class EmailManager : IEmailManager {
    private string mailTemplate;
    private Merchant merchant;
    private string subject;

    public EmailManager(string mailTemplate, Merchant merchant, string subject) {
        this.mailTemplate = mailTemplate;
        this.merchant = merchant;
        this.subject = subject;
    }

    private async Task<string> GetEmailTemplateAsync(string mailTemplate) {
        var mailBody = String.Empty;
        //Get Mail Text Path
        var path = HostingEnvironment.MapPath("/Content/MailText/" + mailTemplate);

        //mailBody = System.IO.File.ReadAllText(HostingEnvironment.MapPath("/Content/MailText/" + mailTemplate));
        using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
        using (var sr = new StreamReader(fs)) {
            mailBody = await sr.ReadToEndAsync();
        }

        return mailBody;
    }


    private string BuildVerifyEmailBodyForMerchant(string mailBody, Merchant merchant) {
        //Replace Custom Variables for Email Body
        var url = System.Web.HttpContext.Current.Request.Url;
        var urlLink = url.OriginalString.Replace(url.PathAndQuery, "");
        merchant.ProviderUserKey = Guid.NewGuid().ToString();
        urlLink = String.Concat(urlLink, "/");
        var verifyUrl = urlLink + "business/verify/" + merchant.ProviderUserKey.ToString();

        //replace variables 
        mailBody = mailBody.Replace("~userLastName~", merchant.Name);
        mailBody = mailBody.Replace("~name~", String.Format("{0} {1}", merchant.FirstName, merchant.LastName));
        mailBody = mailBody.Replace("~companyName~", merchant.Name);
        mailBody = mailBody.Replace("~dateOfRegistration~", merchant.DateOfRegistration.Value.ToShortDateString());
        mailBody = mailBody.Replace("~verifyUrl~", verifyUrl);
        mailBody = mailBody.Replace("~email~", merchant.Email);

        return mailBody;
    }

    private MailMessage BuildEmailMessage(string body, string subject, Merchant merchant) {
        var msg = new MailMessage();

        msg.From = new MailAddress("no-reply@mydomain.com");
        msg.To.Add(merchant.Email.ToString());
        msg.Subject = subject;
        msg.Body = body;

        return msg;
    }

    public async Task SendEmailAsync() {
        var emailTemplate = await GetEmailTemplateAsync(mailTemplate);

        var emailBody = BuildVerifyEmailBodyForMerchant(emailTemplate, merchant);

        var emailToSend = BuildEmailMessage(emailBody, subject, merchant);

        using (var client = new SmtpClient()) {
            await client.SendMailAsync(emailToSend);
        }
    }
}