发送邮件几乎是软件系统中必不可少的功能,在Asp.Net Core 中我们可以使用MailKit发送邮件,MailKit发送邮件比较简单,网上有许多可以参考的文章,但是应该注意附件名长度,和附件名不能出现中文的问题,如果你遇到了这样的问题可以参考我之前写的这篇博客Asp.Net Core MailKit 完美附件(中文名、长文件名)。
在我们简单搜索网络,并成功解决了附件的问题之后,我们已经能够发送邮件啦!不过另一个问题显现出来——发送邮件太慢了,没错,在我使用QQ邮箱发送时,单封邮件发送大概要用1.5秒左右,用户可能难以忍受请求发生1.5秒的延迟。
所以,我们必须解决这个问题,我们的解决办法就是使用邮件队列来发送邮件
设计邮件队列
Ok, 第一步就是规划我们的邮件队列有什么
EmailOptions
我们得有一个邮件Options类,来存储邮件相关的选项
/// <summary>
/// 邮件选项
/// </summary>
public class EmailOptions{
public bool DisableOAuth { get; set; }
public string DisplayName { get; set; }
public string Host { get; set; } // 邮件主机地址public string Password { get; set; }
public int Port { get; set; }
public string UserName { get; set; }
public int SleepInterval { get; set; } = 3000;...
SleepInterval
是睡眠间隔,因为目前我们实现的队列是进程内的独立线程,发送器会循环读取队列,当队列是空的时候,我们应该让线程休息一会,不然无限循环会消耗大量CPU资源
然后我们还需要的就是 一个用于存储邮件的队列,或者叫队列提供器,总之我们要将邮件存储起来。以及一个发送器,发送器不断的从队列中读取邮件并发送。还需要一个邮件写入工具,想要发送邮件的代码使用写入工具将邮件转储到队列中。
那么我们设计的邮件队列事实上就有了三个部分:
队列存储提供器(邮件的事实存储)
邮件发送机 (不断读取队列中的邮件,并发送)
邮件服务 (想法送邮件时,调用邮件服务,邮件服务会将邮件写入队列)
队列存储提供器设计
那么我们设计的邮件队列提供器接口如下:
public interface IMailQueueProvider{
void Enqueue(MailBox mailBox);
bool TryDequeue(out MailBox mailBox);
int Count { get; }
bool IsEmpty { get; }...
四个方法,入队、出队、队列剩余邮件数量、队列是否是空,我们对队列的基本需求就是这样。
MailBox是对邮件的封装,并不复杂,稍后会介绍到
邮件服务设计
public interface IMailQueueService{
void Enqueue(MailBox box);
对于想要发送邮件的组件或者代码部分来讲,只需要将邮件入队,这就足够了
邮件发送机(兼邮件队列管理器)设计
public interface IMailQueueManager{
void Run();
void Stop();
bool IsRunning { get; }
int Count { get; }
启动队列,停止队列,队列运行中状态,邮件计数
现在,三个主要部分就设计好了,我们先看下MailBox
,接下来就去实现这三个接口
MailBox
MailBox 如下:
public class MailBox{
public IEnumerable<IAttachment> Attachments { get; set; }
public string Body { get; set; }
public IEnumerable<string> Cc { get; set; }
public bool IsHtml { get; set; }
public string Subject { get; set; }
public IEnumerable<string> To { get; set; }...
这里面没什么特殊的,大家一看便能理解,除了IEnumerable<IAttachment> Attachments { get; set; }
。
附件的处理
在发送邮件中最复杂的就是附件了,因为附件体积大,往往还涉及非托管资源(例如:文件),所以附件处理一定要小心,避免留下漏洞和bug。
在MailKit中附件实际上是流Stream
,例如下面的代码:
attachment = new MimePart(contentType)
{Content = new MimeContent(fs),ContentDisposition = new ContentDisposition(ContentDisposition.Attachment),ContentTransferEncoding = ContentEncoding.Base64,
};
其中new MimeContent(fs)
是创建的Content,fs是Stream
,MimeContent的构造函数如下:
public MimeContent(Stream stream, ContentEncoding encoding = ContentEncoding.Default)
所以我们的设计的附件是基于Stream
的。
一般情况附件是磁盘上的文件,或者内存流MemoryStream
或者 byte[]数据。附件需要实际的文件的流Stream
和一个附件名,所以附件接口设计如下:
public interface IAttachment : IDisposable{ Stream GetFileStream(); string GetName();
那么我们默认实现了两中附件类型 物理文件附件和内存文件附件,byte[]数据可以轻松的转换成 内存流,所以没有写这种
MemoryStreamAttechment
public class MemoryStreamAttechment : IAttachment{
private readonly MemoryStream _stream;
private readonly string _fileName;
public MemoryStreamAttechment(MemoryStream stream, string fileName) {_stream = stream;_fileName = fileName;}
public void Dispose() => _stream.Dispose();
public Stream GetFileStream() => _stream;
public string GetName() => _fileName;
内存流附件实现要求在创建时传递一个 MemoryStream和附件名称,比较简单
物理文件附件
public class PhysicalFileAttachment : IAttachment{
public PhysicalFileAttachment(string absolutePath) {
if (!File.Exists(absolutePath)){
throw new FileNotFoundException("文件未找到", absolutePath);}AbsolutePath = absolutePath;}
private FileStream _stream;
public string AbsolutePath { get; }
public void Dispose() {_stream.Dispose();}
public Stream GetFileStream() {
if (_stream == null){_stream = new FileStream(AbsolutePath, FileMode.Open);} return _stream;} public string GetName() {
return System.IO.Path.GetFileName(AbsolutePath);...
这里,我们要注意的是创建FileStream的时机,是在请求GetFileStream
方法时,而不是构造函数中,因为创建FileStream
FileStream会占用文件,如果我们发两封邮件使用了同一个附件,那么会抛出异常。而写在GetFileStream
方法中相对比较安全(除非发送器是并行的)
实现邮件队列
在我们这篇文章中,我们实现的队列提供器是基于内存的,日后呢我们还可以实现其它的基于其它存储模式的,比如数据库,外部持久性队列等等,另外基于内存的实现不是持久的,一旦程序崩溃。未发出的邮件就会boom然后消失 XD...
邮件队列提供器IMailQueueProvider
实现
代码如下:
public class MailQueueProvider : IMailQueueProvider{
private static readonly ConcurrentQueue<MailBox> _mailQueue = new ConcurrentQueue<MailBox>(); public int Count => _mailQueue.Count; public bool IsEmpty => _mailQueue.IsEmpty; public void Enqueue(MailBox mailBox) {_mailQueue.Enqueue(mailBox);} public bool TryDequeue(out MailBox mailBox) { return _mailQueue.TryDequeue(out mailBox);}
本文的实现是一个 ConcurrentQueue
邮件服务IMailQueueService
实现
代码如下:
public class MailQueueService : IMailQueueService{ private readonly IMailQueueProvider _provider; /// <summary>/// 初始化实例/// </summary>/// <param name="provider"></param>public MailQueueService(IMailQueueProvider provider) {_provider = provider;} /// <summary>/// 入队/// </summary>/// <param name="box"></param>public void Enqueue(MailBox box) {_provider.Enqueue(box);}
这里,我们的服务依赖于IMailQueueProvider
,使用了其入队功能
邮件发送机IMailQueueManager
实现
这个相对比较复杂,我们先看下完整的类,再逐步解释:
public class MailQueueManager : IMailQueueManager{ private readonly SmtpClient _client; private readonly IMailQueueProvider _provider; private readonly ILogger<MailQueueManager> _logger; private readonly EmailOptions _options; private bool _isRunning = false; private bool _tryStop = false; private Thread _thread; /// <summary>/// 初始化实例/// </summary>/// <param name="provider"></param>/// <param name="options"></param>/// <param name="logger"></param>public MailQueueManager(IMailQueueProvider provider, IOptions<EmailOptions> options, ILogger<MailQueueManager> logger) {_options = options.Value;_client = new SmtpClient{ // For demo-purposes, accept all SSL certificates (in case the server supports STARTTLS)ServerCertificateValidationCallback = (s, c, h, e) => true}; // Note: since we don't have an OAuth2 token, disable// the XOAUTH2 authentication mechanism.if (_options.DisableOAuth){_client.AuthenticationMechanisms.Remove("XOAUTH2");}_provider = provider;_logger = logger;} /// <summary>/// 正在运行/// </summary>public bool IsRunning => _isRunning; /// <summary>/// 计数/// </summary>public int Count => _provider.Count; /// <summary>/// 启动队列/// </summary>public void Run() { if (_isRunning || (_thread != null && _thread.IsAlive)){_logger.LogWarning("已经运行,又被启动了,新线程启动已经取消"); return;}_isRunning = true;_thread = new Thread(StartSendMail){Name = "PmpEmailQueue",IsBackground = true,};_logger.LogInformation("线程即将启动");_thread.Start();_logger.LogInformation("线程已经启动,线程Id是:{0}", _thread.ManagedThreadId);} /// <summary>/// 停止队列/// </summary>public void Stop() { if (_tryStop){ return;}_tryStop = true;} private void StartSendMail() { var sw = new Stopwatch(); try{ while (true){ if (_tryStop){ break;} if (_provider.IsEmpty){_logger.LogTrace("队列是空,开始睡眠");Thread.Sleep(_options.SleepInterval); continue;} if (_provider.TryDequeue(out MailBox box)){_logger.LogInformation("开始发送邮件 标题:{0},收件人 {1}", box.Subject, box.To.First());sw.Restart();SendMail(box);sw.Stop();_logger.LogInformation("发送邮件结束标题:{0},收件人 {1},耗时{2}", box.Subject, box.To.First(), sw.Elapsed.TotalSeconds);}}} catch (Exception ex){_logger.LogError(ex, "循环中出错,线程即将结束");_isRunning = false;}_logger.LogInformation("邮件发送线程即将停止,人为跳出循环,没有异常发生");_tryStop = false;_isRunning = false;} private void SendMail(MailBox box) { if (box == null){ throw new ArgumentNullException(nameof(box));} try{MimeMessage message = ConvertToMimeMessage(box);SendMail(message);} catch (Exception exception){_logger.LogError(exception, "发送邮件发生异常主题:{0},收件人:{1}", box.Subject, box.To.First());} finally{ if (box.Attachments != null && box.Attachments.Any()){ foreach (var item in box.Attachments){item.Dispose();}}}} private MimeMessage ConvertToMimeMessage(MailBox box) { var message = new MimeMessage(); var from = InternetAddress.Parse(_options.UserName); from.Name = _options.DisplayName;message.From.Add(from); if (!box.To.Any()){ throw new ArgumentNullException("to必须含有值");}message.To.AddRange(box.To.Convert()); if (box.Cc != null && box.Cc.Any()){message.Cc.AddRange(box.Cc.Convert());}message.Subject = box.Subject; var builder = new BodyBuilder(); if (box.IsHtml){builder.HtmlBody = box.Body;} else{builder.TextBody = box.Body;} if (box.Attachments != null && box.Attachments.Any()){ foreach (var item in GetAttechments(box.Attachments)) {builder.Attachments.Add(item);}}message.Body = builder.ToMessageBody(); return message;} private void SendMail(MimeMessage message) { if (message == null){ throw new ArgumentNullException(nameof(message));} try{_client.Connect(_options.Host, _options.Port, false); // Note: only needed if the SMTP server requires authenticationif (!_client.IsAuthenticated){_client.Authenticate(_options.UserName, _options.Password);}_client.Send(message);} finally{_client.Disconnect(false);}} private AttachmentCollection GetAttechments(IEnumerable<IAttachment> attachments) { if (attachments == null){ throw new ArgumentNullException(nameof(attachments));}AttachmentCollection collection = new AttachmentCollection();List<Stream> list = new List<Stream>(attachments.Count()); foreach (var item in attachments){ var fileName = item.GetName(); var fileType = MimeTypes.GetMimeType(fileName); var contentTypeArr = fileType.Split('/'); var contentType = new ContentType(contentTypeArr[0], contentTypeArr[1]);MimePart attachment = null;Stream fs = null; try{fs = item.GetFileStream();list.Add(fs);} catch (Exception ex){_logger.LogError(ex, "读取文件流发生异常");fs?.Dispose(); continue;}attachment = new MimePart(contentType){Content = new MimeContent(fs),ContentDisposition = new ContentDisposition(ContentDisposition.Attachment),ContentTransferEncoding = ContentEncoding.Base64,}; var charset = "UTF-8";attachment.ContentType.Parameters.Add(charset, "name", fileName);attachment.ContentDisposition.Parameters.Add(charset, "filename", fileName); foreach (var param in attachment.ContentDisposition.Parameters){param.EncodingMethod = ParameterEncodingMethod.Rfc2047;} foreach (var param in attachment.ContentType.Parameters){param.EncodingMethod = ParameterEncodingMethod.Rfc2047;}collection.Add(attachment);} return collection;}
}
在构造函数中请求了另外三个服务,并且初始化了SmtpClient
(这是MailKit中的)
public MailQueueManager(IMailQueueProvider provider, IOptions<EmailOptions> options, ILogger<MailQueueManager> logger){_options = options.Value;_client = new SmtpClient{ // For demo-purposes, accept all SSL certificates (in case the server supports STARTTLS)ServerCertificateValidationCallback = (s, c, h, e) => true}; // Note: since we don't have an OAuth2 token, disable// the XOAUTH2 authentication mechanism.if (_options.DisableOAuth){_client.AuthenticationMechanisms.Remove("XOAUTH2");}_provider = provider;_logger = logger;}
启动队列时创建了新的线程,并且将线程句柄保存起来:
public void Run() { if (_isRunning || (_thread != null && _thread.IsAlive)){_logger.LogWarning("已经运行,又被启动了,新线程启动已经取消"); return;}_isRunning = true;_thread = new Thread(StartSendMail){Name = "PmpEmailQueue",IsBackground = true,};_logger.LogInformation("线程即将启动");_thread.Start();_logger.LogInformation("线程已经启动,线程Id是:{0}", _thread.ManagedThreadId);}
线程启动时运行了方法StartSendMail
:
private void StartSendMail() { var sw = new Stopwatch(); try{ while (true){ if (_tryStop){ break;} if (_provider.IsEmpty){_logger.LogTrace("队列是空,开始睡眠");Thread.Sleep(_options.SleepInterval); continue;} if (_provider.TryDequeue(out MailBox box)){_logger.LogInformation("开始发送邮件 标题:{0},收件人 {1}", box.Subject, box.To.First());sw.Restart();SendMail(box);sw.Stop();_logger.LogInformation("发送邮件结束标题:{0},收件人 {1},耗时{2}", box.Subject, box.To.First(), sw.Elapsed.TotalSeconds);}}} catch (Exception ex){_logger.LogError(ex, "循环中出错,线程即将结束");_isRunning = false;}_logger.LogInformation("邮件发送线程即将停止,人为跳出循环,没有异常发生");_tryStop = false;_isRunning = false;}
这个方法不断的从队列读取邮件并发送,当 遇到异常,或者_tryStop
为true
时跳出循环,此时线程结束,注意我们会让线程睡眠,在适当的时候。
接下来就是方法SendMail
了:
private void SendMail(MailBox box) { if (box == null){ throw new ArgumentNullException(nameof(box));} try{MimeMessage message = ConvertToMimeMessage(box);SendMail(message);} catch (Exception exception){_logger.LogError(exception, "发送邮件发生异常主题:{0},收件人:{1}", box.Subject, box.To.First());} finally{ if (box.Attachments != null && box.Attachments.Any()){ foreach (var item in box.Attachments){item.Dispose();...
这里有一个特别要注意的就是在发送之后释放附件(非托管资源):
foreach (var item in box.Attachments)
{item.Dispose();...
发送邮件的核心代码只有两行:
MimeMessage message = ConvertToMimeMessage(box);SendMail(message);
第一行将mailbox转换成 MailKit使用的MimeMessage实体,第二步切实的发送邮件
为什么,我们的接口中没有直接使用MimeMessage而是使用MailBox?
因为MimeMessage比较繁杂,而且附件的问题不易处理,所以我们设计接口时单独封装MailBox简化了编程接口
转换一共两步,1是主体转换,比较简单。二是附件的处理这里涉及到附件名中文编码的问题。
private MimeMessage ConvertToMimeMessage(MailBox box) { var message = new MimeMessage(); var from = InternetAddress.Parse(_options.UserName); from.Name = _options.DisplayName;message.From.Add(from); if (!box.To.Any()){ throw new ArgumentNullException("to必须含有值");}message.To.AddRange(box.To.Convert()); if (box.Cc != null && box.Cc.Any()){message.Cc.AddRange(box.Cc.Convert());}message.Subject = box.Subject; var builder = new BodyBuilder(); if (box.IsHtml){builder.HtmlBody = box.Body;} else{builder.TextBody = box.Body;} if (box.Attachments != null && box.Attachments.Any()){ foreach (var item in GetAttechments(box.Attachments)) {builder.Attachments.Add(item);}}message.Body = builder.ToMessageBody(); return message;} private AttachmentCollection GetAttechments(IEnumerable<IAttachment> attachments) { if (attachments == null){ throw new ArgumentNullException(nameof(attachments));}AttachmentCollection collection = new AttachmentCollection();List<Stream> list = new List<Stream>(attachments.Count()); foreach (var item in attachments){ var fileName = item.GetName(); var fileType = MimeTypes.GetMimeType(fileName); var contentTypeArr = fileType.Split('/'); var contentType = new ContentType(contentTypeArr[0], contentTypeArr[1]);MimePart attachment = null;Stream fs = null; try{fs = item.GetFileStream();list.Add(fs);} catch (Exception ex){_logger.LogError(ex, "读取文件流发生异常");fs?.Dispose(); continue;}attachment = new MimePart(contentType){Content = new MimeContent(fs),ContentDisposition = new ContentDisposition(ContentDisposition.Attachment),ContentTransferEncoding = ContentEncoding.Base64,}; var charset = "UTF-8";attachment.ContentType.Parameters.Add(charset, "name", fileName);attachment.ContentDisposition.Parameters.Add(charset, "filename", fileName); foreach (var param in attachment.ContentDisposition.Parameters){param.EncodingMethod = ParameterEncodingMethod.Rfc2047;} foreach (var param in attachment.ContentType.Parameters){param.EncodingMethod = ParameterEncodingMethod.Rfc2047;}collection.Add(attachment);} return collection;}
在转化附件时下面的代码用来处理附件名编码问题:
var charset = "UTF-8";
attachment.ContentType.Parameters.Add(charset, "name", fileName);
attachment.ContentDisposition.Parameters.Add(charset, "filename", fileName);foreach (var param in attachment.ContentDisposition.Parameters)
{param.EncodingMethod = ParameterEncodingMethod.Rfc2047;
}foreach (var param in attachment.ContentType.Parameters)
{param.EncodingMethod = ParameterEncodingMethod.Rfc2047;
}
到这了我们的邮件队列就基本完成了,接下来就是在程序启动后,启动队列,找到 Program.cs文件,并稍作改写如下:
var host = BuildWebHost(args);var provider = host.Services;
provider.GetRequiredService<IMailQueueManager>().Run();
host.Run();
这里在host.Run()
主机启动之前,我们获取了IMailQueueManager
并启动队列(别忘了注册服务)。
运行程序我们会看到控制台每隔3秒就会打出日志:
info: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[0]User profile is available. Using 'C:\Users\Administrator\AppData\Local\ASP.NET\DataProtection-Keys' as key repository and Windows DPAPI to encrypt keys at rest.info: MailQueueManager[0]线程即将启动info: MailQueueManager[0]线程已经启动,线程Id是:9trce: MailQueueManager[0]队列是空,开始睡眠
Hosting environment: Development
Content root path: D:\publish
Now listening on: http://[::]:5000Application started. Press Ctrl+C to shut down.trce: MailQueueManager[0]队列是空,开始睡眠trce: MailQueueManager[0]队列是空,开始睡眠
到此,我们的邮件队列就完成了! :D
原文地址:http://www.cnblogs.com/rocketRobin/p/9294845.html
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