转换MailMessage原始文本

问题描述

有没有简单的方法来一个System.Net.Mail.MailMessage对象转换为原始邮件文本，当您在记事本中打开一个EML文件等。

Is there any easy way to convert a System.Net.Mail.MailMessage object to the raw mail message text, like when you open a eml file in notepad.

推荐答案

下面是同样的解决方案，但作为一个扩展的方法来 MailMessage 。

Here's the same solution, but as an extension method to MailMessage.

部分的反射开销是由静态背景下抓住了 ConstructorInfo 和的MethodInfo 成员一旦最小化。

Some of the reflection overhead is minimized by grabbing the ConstructorInfo and MethodInfo members once in the static context.

/// <summary>
/// Uses reflection to get the raw content out of a MailMessage.
/// </summary>
public static class MailMessageExtensions
{
    private static readonly BindingFlags Flags = BindingFlags.Instance | BindingFlags.NonPublic;
    private static readonly Type MailWriter = typeof(SmtpClient).Assembly.GetType("System.Net.Mail.MailWriter");
    private static readonly ConstructorInfo MailWriterConstructor = MailWriter.GetConstructor(Flags, null, new[] { typeof(Stream) }, null);
    private static readonly MethodInfo CloseMethod = MailWriter.GetMethod("Close", Flags);
    private static readonly MethodInfo SendMethod = typeof(MailMessage).GetMethod("Send", Flags);

    /// <summary>
    /// A little hack to determine the number of parameters that we
    /// need to pass to the SaveMethod.
    /// </summary>
    private static readonly bool IsRunningInDotNetFourPointFive = SendMethod.GetParameters().Length == 3;

    /// <summary>
    /// The raw contents of this MailMessage as a MemoryStream.
    /// </summary>
    /// <param name="self">The caller.</param>
    /// <returns>A MemoryStream with the raw contents of this MailMessage.</returns>
    public static MemoryStream RawMessage(this MailMessage self)
    {
        var result = new MemoryStream();
        var mailWriter = MailWriterConstructor.Invoke(new object[] { result });
        SendMethod.Invoke(self, Flags, null, IsRunningInDotNetFourPointFive ? new[] { mailWriter, true, true } : new[] { mailWriter, true }, null);
        result = new MemoryStream(result.ToArray());
        CloseMethod.Invoke(mailWriter, Flags, null, new object[] { }, null);
        return result;
    }
}

要抓住根本的MemoryStream ：

var email = new MailMessage();
using (var m = email.RawMessage()) {
    // do something with the raw message
}

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