使用 POP3 客户端进行异步电子邮件处理

使用 Pop3Client 的异步操作

使用 Aspose.Email 也可以异步处理消息 Pop3Client。本文展示了如何异步检索邮箱中的消息，并展示了如何使用 MailQuery。将另行展示如何使用基于任务的异步模式（TAP）方法。

异步检索邮件

以下代码片段展示了如何异步检索邮件。

Pop3Client client = new Pop3Client();
client.Host = "pop.gmail.com";
client.Port = 995;
client.SecurityOptions = SecurityOptions.SSLImplicit;
client.Username = "username";
client.Password = "password";
            
try
{
    Pop3MessageInfoCollection messages = client.ListMessages();
    Console.WriteLine("Total Number of Messages in inbox:" + messages.Count);
    AutoResetEvent evnt = new AutoResetEvent(false);
    MailMessage message = null;
    AsyncCallback callback = delegate(IAsyncResult ar)
    {
        message = client.EndFetchMessage(ar);
        evnt.Set();
    };
    client.BeginFetchMessage(messages[0].SequenceNumber, callback, null);
    evnt.WaitOne();
}
catch (Exception ex)
{
    Console.WriteLine(ex.Message);
}

使用 MailQuery 异步列出消息

该 MailQuery 类可用于指定检索消息列表的搜索条件，示例代码如下所示。

MailQueryBuilder builder = new MailQueryBuilder();
builder.Subject.Contains("Subject");
MailQuery query = builder.GetQuery();
IAsyncResult asyncResult = client.BeginListMessages(query);
Pop3MessageInfoCollection messages = client.EndListMessages(asyncResult);

中断 TAP 方法

从 .NET Framework 4.5 开始，您可以使用按照 TAP 模型实现的异步方法。下面的代码片段展示了如何使用任务式异步模式（TAP）方法来接收邮箱信息，方法名为 GetMailboxInfoAsync 然后在一段时间后中断此过程。

using (Pop3Client client = new Pop3Client(host, 995, senderEmail, password, SecurityOptions.Auto))
{
    CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
    AutoResetEvent autoResetEvent = new AutoResetEvent(false);
    Exception exception = null;

    ThreadPool.QueueUserWorkItem(delegate
    {
        try
        {
            // start receiving mailbox information
            var task = client.GetMailboxInfoAsync(cancellationTokenSource.Token);
            Pop3MailboxInfo mailboxInfo = task.GetAwaiter().GetResult();
            Console.WriteLine("Message count: " + mailboxInfo.MessageCount);
        }
        catch (Exception e)
        {
            exception = e;
        }
        finally
        {
            autoResetEvent.Set();
        }
    });

    Thread.Sleep(2000);

    // stop receiving mailbox information
    cancellationTokenSource.Cancel();
    autoResetEvent.WaitOne();

    if (exception is OperationCanceledException)
        Console.WriteLine("Operation has been interrupted: " + exception.Message);
}