使用 Exchange 中的 EWS 获取附件

了解如何通过在 Exchange 中使用 EWS 托管 API 或 EWS 从 EWS 项目中获取附件。

您可以使用 EWS 托管 API 或 EWS 从项目中获取附件。 由于最初对获取项目的调用包含有关项目上的附件集合的元数据，因此检索附件的过程始终为两个步骤。 首先，检索项目。 接下来，检索附件。

表1。用于添加附件的 EWS 托管 API 方法和 EWS 操作

任务	EWS 托管的 API 方法	EWS 操作
获取项目附件	先绑定后接ItemAttachment的项	GetItem后接GetAttachment
获取文件附件	先绑定后接FileAttachment的项	GetItem后接GetAttachment

使用 EWS 托管 API 从电子邮件获取附件

下面的代码示例演示如何使用Bind方法获取EmailMessage对象，然后循环访问附件集合，并根据需要对每个附件调用FileAttachment或ItemAttachment方法。 每个文件附件都保存到 C:\temp\ 文件夹，每个项目附件都会加载到内存中。 有关如何保存项目附件的信息，请参阅使用 EWS 托管 API 保存附加的电子邮件。

此示例假定service是有效的ExchangeService对象，则itemid是将从中检索附件的邮件的itemid ，并且用户已通过 Exchange 服务器的身份验证。

public static void GetAttachmentsFromEmail(ExchangeService service, ItemId itemId)
{
    // Bind to an existing message item and retrieve the attachments collection.
    // This method results in an GetItem call to EWS.
    EmailMessage message = EmailMessage.Bind(service, itemId, new PropertySet(ItemSchema.Attachments));
    // Iterate through the attachments collection and load each attachment.
    foreach (Attachment attachment in message.Attachments)
    {
        if (attachment is FileAttachment)
        {
            FileAttachment fileAttachment = attachment as FileAttachment;
            // Load the attachment into a file.
            // This call results in a GetAttachment call to EWS.
            fileAttachment.Load("C:\\temp\\" + fileAttachment.Name);
           
            Console.WriteLine("File attachment name: " + fileAttachment.Name);
        }
        else // Attachment is an item attachment.
        {
            ItemAttachment itemAttachment = attachment as ItemAttachment;
            // Load attachment into memory and write out the subject.
            // This does not save the file like it does with a file attachment.
            // This call results in a GetAttachment call to EWS.
            itemAttachment.Load();
            Console.WriteLine("Item attachment name: " + itemAttachment.Name);
        }
    }
}

使用 EWS 从电子邮件获取附件

若要使用 EWS 获取附件，首先需要检索邮件和附件集合，以获取要检索的附件的AttachmentId （GetAttachment 和 DeleteAttachment） 。 在具有一个或多个要检索的AttachmentId值之后，调用GetAttachment操作以加载附件的所有属性。

下面的代码示例演示如何使用GetItem操作来获取电子邮件和邮件附件的集合。 这也是当您使用 EWS 托管 API从电子邮件获取所有附件时，EWS 托管 api 发送的第一个 XML 请求。 为了提高可读性，某些属性的值会缩短。

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xmlns:m="https://schemas.microsoft.com/exchange/services/2006/messages"
               xmlns:t="https://schemas.microsoft.com/exchange/services/2006/types"
               xmlns:soap="https://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header>
    <t:RequestServerVersion Version="Exchange207_SP1" />
  </soap:Header>
  <soap:Body>
    <m:GetItem>
      <m:ItemShape>
        <t:BaseShape>IdOnly</t:BaseShape>
        <t:AdditionalProperties>
          <t:FieldURI FieldURI="item:Attachments" />
        </t:AdditionalProperties>
      </m:ItemShape>
      <m:ItemIds>
        <t:ItemId Id="ERu/AAA=" />
      </m:ItemIds>
    </m:GetItem>
  </soap:Body>
</soap:Envelope>

服务器使用GetItemResponse邮件响应GetItem请求，其中包括 ResponseCode 值为NoError的ResponseCode值，该值指示电子邮件已成功检索，以及现有附件的AttachmentId值。

<?xml version="1.0" encoding="utf-8"?>
<s:Envelope xmlns:s="https://schemas.xmlsoap.org/soap/envelope/">
  <s:Header>
    <h:ServerVersionInfo MajorVersion="15"
                         MinorVersion="0"
                         MajorBuildNumber="939"
                         MinorBuildNumber="12"
                         Version="V2_11"
                         xmlns:h="https://schemas.microsoft.com/exchange/services/2006/types"
                         xmlns="https://schemas.microsoft.com/exchange/services/2006/types"
                         xmlns:xsd="http://www.w3.org/2001/XMLSchema"
                         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" />
  </s:Header>
  <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <m:GetItemResponse xmlns:m="https://schemas.microsoft.com/exchange/services/2006/messages"
                       xmlns:t="https://schemas.microsoft.com/exchange/services/2006/types">
      <m:ResponseMessages>
        <m:GetItemResponseMessage ResponseClass="Success">
          <m:ResponseCode>NoError</m:ResponseCode>
          <m:Items>
            <t:Message>
              <t:ItemId Id="ERu/AAA="
                        ChangeKey="CQAAABYAAAAFI5DJmZv+TLtyLOLIF1S5AAAYEMnd" />
              <t:Attachments>
                <t:FileAttachment>
                  <t:AttachmentId Id="5zTzlqU=" />
                  <t:Name>FileAttachment.txt</t:Name>
                  <t:Size>212</t:Size>
                  <t:LastModifiedTime>2014-05-14T17:59:30</t:LastModifiedTime>
                  <t:IsInline>false</t:IsInline>
                  <t:IsContactPhoto>false</t:IsContactPhoto>
                </t:FileAttachment>
                <t:ItemAttachment>
                  <t:AttachmentId Id="Ktum21o=" />
                  <t:Name>Attached Message Item</t:Name>
                  <t:Size>3063</t:Size>
                  <t:LastModifiedTime>2014-05-14T17:59:30</t:LastModifiedTime>
                  <t:IsInline>false</t:IsInline>
                </t:ItemAttachment>
              </t:Attachments>
            </t:Message>
          </m:Items>
        </m:GetItemResponseMessage>
      </m:ResponseMessages>
    </m:GetItemResponse>
  </s:Body>
</s:Envelope>

现在您已拥有AttachmentId值，请在要检索的每个附件上调用GetAttachment 。

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xmlns:m="https://schemas.microsoft.com/exchange/services/2006/messages"
               xmlns:t="https://schemas.microsoft.com/exchange/services/2006/types"
               xmlns:soap="https://schemas.xmlsoap.org/soap/envelope/">
  <soap:Header>
    <t:RequestServerVersion Version="Exchange2007_SP1" />
  </soap:Header>
  <soap:Body>
    <m:GetAttachment>
      <m:AttachmentIds>
        <t:AttachmentId Id="5zTzlqU=" />
      </m:AttachmentIds>
    </m:GetAttachment>
  </soap:Body>
</soap:Envelope>

检索项目附件时，服务器会使用GetAttachmentResponse邮件响应GetAttachment请求，其中包括ResponseCode值NoError，表示已成功检索附件，并且附加项目的所有元素（在此示例中为电子邮件）。

<?xml version="1.0" encoding="utf-8"?>
<s:Envelope xmlns:s="https://schemas.xmlsoap.org/soap/envelope/">
  <s:Header>
    <h:ServerVersionInfo MajorVersion="15"
                         MinorVersion="0"
                         MajorBuildNumber="939"
                         MinorBuildNumber="12"
                         Version="V2_11"
                         xmlns:h="https://schemas.microsoft.com/exchange/services/2006/types"
                         xmlns="https://schemas.microsoft.com/exchange/services/2006/types"
                         xmlns:xsd="http://www.w3.org/2001/XMLSchema"
                         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" />
  </s:Header>
  <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <m:GetAttachmentResponse xmlns:m="https://schemas.microsoft.com/exchange/services/2006/messages"
                             xmlns:t="https://schemas.microsoft.com/exchange/services/2006/types">
      <m:ResponseMessages>
        <m:GetAttachmentResponseMessage ResponseClass="Success">
          <m:ResponseCode>NoError</m:ResponseCode>
          <m:Attachments>
            <t:ItemAttachment>
              <t:AttachmentId Id="Ktum21o=" />
              <t:Name>Attached Message Item</t:Name>
              <t:Message>
                <t:ItemClass>IPM.Note</t:ItemClass>
                <t:Subject>Message Item Subject</t:Subject>
                <t:Body BodyType="HTML">&amp;lt;meta http-equiv="Content-Type" 
                    content="text/html; charset=utf-8"&amp;gt;Message Item Body</t:Body>
                <t:Size>2859</t:Size>
                <t:IsSubmitted>false</t:IsSubmitted>
                <t:IsDraft>true</t:IsDraft>
                <t:IsFromMe>false</t:IsFromMe>
                <t:IsResend>false</t:IsResend>
                <t:IsUnmodified>false</t:IsUnmodified>
                <t:DateTimeCreated>2014-05-14T17:59:37Z</t:DateTimeCreated>
                <t:ResponseObjects>
                  <t:ForwardItem />
                </t:ResponseObjects>
                <t:DisplayCc />
                <t:DisplayTo>primary; emaildelegate</t:DisplayTo>
                <t:HasAttachments>false</t:HasAttachments>
                <t:Culture>en</t:Culture>
                <t:EffectiveRights>
                  <t:CreateAssociated>false</t:CreateAssociated>
                  <t:CreateContents>false</t:CreateContents>
                  <t:CreateHierarchy>false</t:CreateHierarchy>
                  <t:Delete>true</t:Delete>
                  <t:Modify>true</t:Modify>
                  <t:Read>true</t:Read>
                </t:EffectiveRights>
                <t:LastModifiedName>primary</t:LastModifiedName>
                <t:LastModifiedTime>2014-05-14T17:59:30Z</t:LastModifiedTime>
                <t:IsAssociated>false</t:IsAssociated>
                <t:WebClientReadFormQueryString>?ItemID=AAMk3D&amp;amp;exvsurl=1&amp;amp;viewmodel=
                    ReadMessageItem</t:WebClientReadFormQueryString>
                <t:ConversationId Id="AAQkADIwM2ZlM2ZlLWMwYjctNDg2N/Rc+d0=" />
                <t:ToRecipients>
                  <t:Mailbox>
                    <t:Name>primary</t:Name>
                    <t:EmailAddress>sadie@contoso.com</t:EmailAddress>
                    <t:RoutingType>SMTP</t:RoutingType>
                    <t:MailboxType>Mailbox</t:MailboxType>
                  </t:Mailbox>
                  <t:Mailbox>
                    <t:Name>emaildelegate</t:Name>
                    <t:EmailAddress>ronnie@contoso.com</t:EmailAddress>
                    <t:RoutingType>SMTP</t:RoutingType>
                    <t:MailboxType>Mailbox</t:MailboxType>
                  </t:Mailbox>
                </t:ToRecipients>
                <t:IsReadReceiptRequested>false</t:IsReadReceiptRequested>
                <t:ConversationIndex>AQHPb55BxR5Fm0Arx0yY4xbL9Fz53Q==</t:ConversationIndex>
                <t:ConversationTopic>Message Item Subject</t:ConversationTopic>
                <t:IsRead>true</t:IsRead>
              </t:Message>
            </t:ItemAttachment>
          </m:Attachments>
        </m:GetAttachmentResponseMessage>
      </m:ResponseMessages>
    </m:GetAttachmentResponse>
  </s:Body>
</s:Envelope>

检索文件附件时，服务器会使用GetAttachmentResponse邮件响应GetAttachment请求，其中包括ResponseCode值NoError，表示已成功检索附件，并且文件附件的所有元素。

<?xml version="1.0" encoding="utf-8"?>
<s:Envelope xmlns:s="https://schemas.xmlsoap.org/soap/envelope/">
  <s:Header>
    <h:ServerVersionInfo MajorVersion="15"
                         MinorVersion="0"
                         MajorBuildNumber="939"
                         MinorBuildNumber="12"
                         Version="V2_11"
                         xmlns:h="https://schemas.microsoft.com/exchange/services/2006/types"
                         xmlns="https://schemas.microsoft.com/exchange/services/2006/types"
                         xmlns:xsd="http://www.w3.org/2001/XMLSchema"
                         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" />
  </s:Header>
  <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <m:GetAttachmentResponse xmlns:m="https://schemas.microsoft.com/exchange/services/2006/messages"
                             xmlns:t="https://schemas.microsoft.com/exchange/services/2006/types">
      <m:ResponseMessages>
        <m:GetAttachmentResponseMessage ResponseClass="Success">
          <m:ResponseCode>NoError</m:ResponseCode>
          <m:Attachments>
            <t:FileAttachment>
              <t:AttachmentId Id="5zTzlqU=" />
              <t:Name>FileAttachment.txt</t:Name>
              <t:Content>VGhpcyBpcyBhIGZpbGUgYXR0YWNobWVudC4=</t:Content>
            </t:FileAttachment>
          </m:Attachments>
        </m:GetAttachmentResponseMessage>
      </m:ResponseMessages>
    </m:GetAttachmentResponse>
  </s:Body>
</s:Envelope>

使用 EWS 托管 API 保存附加的电子邮件

为了使用 EWS 托管 API 保存电子邮件附件的内容，您需要将MimeContent保存到文件中。 在执行此操作时，将丢失对项目设置的任何扩展属性，例如后续标志和类别。 此示例将电子邮件附件保存到 "C:\temp" 文件夹中。

请注意，不能将项目附件移动或复制到另一个文件夹，因为项目附件不是强类型项目，因此，如果您尝试将附件移动到其他文件夹，请使用以下代码示例，然后将该文件导入到其他文件夹中。

public static void SaveEmailAttachment(ExchangeService service, ItemId itemId)
{
    // Bind to an existing message item and retrieve the attachments collection.
    // This method results in an GetItem call to EWS.
    EmailMessage message = EmailMessage.Bind(service, itemId, new PropertySet(ItemSchema.Attachments));
    
    foreach (Attachment attachment in message.Attachments)
    {
        if (attachment is ItemAttachment)
        {
            ItemAttachment itemAttachment = attachment as ItemAttachment;
            itemAttachment.Load(ItemSchema.MimeContent);
            string fileName = "C:\\Temp\\" + itemAttachment.Item.Subject + ".eml";
            // Write the bytes of the attachment into a file.
            File.WriteAllBytes(fileName, itemAttachment.Item.MimeContent.Content);
            Console.WriteLine("Email attachment name: "+ itemAttachment.Item.Subject + ".eml");
        }
    }
}

另请参阅

• 附件和 EWS Exchange 中

• 使用 Exchange 中的 EWS 添加附件

• 使用 Exchange 中的 EWS 删除附件