无法使用 EWS 下载项目附件

Question

我在使用EWS下载"ItemAttachment"类型的附件时遇到问题。以下是我用来下载附件的代码：

 PropertySet ps = new PropertySet(BasePropertySet.FirstClassProperties);
                    ps.add(ItemSchema.MimeContent);
                    ia = (ItemAttachment) attach;
                    ia.load(ps);
                    //ia.load();
                    System.out.println(ia.getItem().getSubject());
                    MimeContent mc = ia.getItem().getMimeContent();
                    String itemName = ia.getName().replace(" ","").replace(":","-").trim();
                    attname.add(itemName);
                    System.out.println(itemName);
                    byte[] contentBytes = mc.getContent();
                    theStream = new FileOutputStream(
                            "C:\Users\502000317\Desktop\test\"
                                    + itemName);
                    ia.getItem().getAttachments();
                    theStream.write(contentBytes);
                    theStream.flush();

但是当我尝试执行这个时，我得到了以下错误：

java.lang.ClassCastException：无法将microsoft.exchange.webservices.data.PropertySet强制转换为microsoft.exchange.webservices.da.PropertyDefinitionBase位于microsoft.exchange.webservices.data.PropertySet.writeAdditionalPropertiesToXml（未知源）位于microsoft.exchange.webservices.data.GetAttachmentRequest.writeElementsToXml（未知源）位于microsoft.exchange.webservices.data.ServiceRequestBase.writeBodyToXml（未知源）位于microsoft.exchange.webservices.data.ServiceRequestBase.writeToXml（未知源）位于microsoft.exchange.webservices.data.ServiceRequestBase.buildEwsHttpWebRequest（未知源）位于microsoft.exchange.webservices.data.ServiceRequestBase.validateAndEmitRequest（未知源）位于microsoft.exchange.webservices.data.SimpleServiceRequestBase.internalExecute（未知源）位于microsoft.exchange.webservices.data.MultiResponseServiceRequest.execute（未知来源）位于microsoft.exchange.webservices.data.ExchangeService.internalGetAttachments（未知来源）位于microsoft.exchange.webservices.data.ExchangeService.getAttachment（未知来源）位于microsoft.exchange.webservices.data.Attachment.internalLoad（未知来源）位于microsoft.exchange.webservices.data.ItemAttachment.load（未知来源）网址：com.medpro.roundrobinmailer.RoundRobinMail.sendunreadmailtoRRRecpt（RoundRobinMail.java:173）网址：com.medpro.roundrobinmailer.roundrobinmailer.delegateAccessSearchEmailWithFilter（roundrobinmailer.java:114）网址：com.medpro.roundrobinmailer.roundrobinmailer.main（RoundRobinLoader.java:57）

代码在以下位置中断：ia负荷（ps）；

这把我逼疯了。请帮忙。

谢谢Tushar

Answer 1

这是EWS Java中的一个已知错误。幸运的是，它是开源的，可以在Github:上使用

https://github.com/OfficeDev/ews-java-api

参见第12期。问题出在ExchangeService.internalGetAttachments（）中。其中有一些非常丑陋的代码，使用了无法解释的泛型和非类型化集合的混合。因此，当它本应复制到各个PropertyDefinitionBase对象上时，它最终会将整个PropertySet添加到列表中，这就是您看到ClassCastException的原因。看一看。如果它还没有被修复，那么你自己应该不难做到。

Answer 2

/*@作者rmanssink

此方法下载与电子邮件相关的所有附件

我认为你会出错，因为在加载之前你需要绑定项目。。以下是运行良好的代码。。。经过测试，目前正在我的项目中使用。。希望能有所帮助。。祝好运

*/

public static void getAttachments(ExchangeService service, ItemId id) throws Exception{
    Item item = Item.bind(service, id);
    item.load();
    if (item.getHasAttachments()){ 
        AttachmentCollection attachmentsCol = item.getAttachments();
        int NumberOfAttachments = attachmentsCol.getCount();
        System.out.println("Attchments being Downloaded:: "+NumberOfAttachments);
        String directoryName = "C:\MSExchangeEmail\WebContent\attachments";
        File theDir = new File(directoryName);
        // if the directory does not exist, create it
        if (!theDir.exists()) {
          System.out.println("creating directory: " + directoryName);
          boolean result = false;
          try{
              result = theDir.mkdir();
           } catch(SecurityException se){
              //handle it
           }        
           if(result) {    
             System.out.println("DIR created: "+result);  
           }
        }  
        for (int i = 0; i < NumberOfAttachments; i++) { 
            FileAttachment attachment = (FileAttachment)attachmentsCol.getPropertyAtIndex(i); 
            attachment.load(directoryName+"\"+attachment.getName());
        }
    } 
}