Salesforce 使用Code发送带附件邮件

//当附件不为空的时候，将附件带到邮件上
Messaging.EmailFileAttachment[] EmailAttList = new Messaging.EmailFileAttachment[1];
if(BillingAttachment.Body != null)
{
        Messaging.EmailFileAttachment EmailAtt = new Messaging.EmailFileAttachment();
        EmailAtt.setBody(BillingAttachment.Body);
        EmailAtt.setFileName(BillingAttachment.Name);
        EmailAttList[0] = EmailAtt;
}
 
//附件列表
List<Messaging.EmailFileAttachment> list_Attachment = new List<Messaging.EmailFileAttachment>();
for(Attachment att : [Select ParentId, Name, Id, Body From Attachment where ParentId = :op.Id])
{
    if(att.Body != null && att.Body.size() != 0)
    {
        Messaging.EmailFileAttachment efa = new Messaging.EmailFileAttachment();
	List<Messaging.EmailFileAttachment> list_Att = new List<Messaging.EmailFileAttachment>();
	    efa.setFileName(att.Name);
	    efa.setBody(att.Body);
        list_Attachment.add(efa);
     }
}
 
Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
String emailBody = 'Dear ' + con.Name + ':<br/><br/>' + htmlBody;
mail.setSubject(subject);
mail.setSenderDisplayName('Haitian Logistics Inc.');
mail.setHtmlBody(emailBody);
mail.setTargetObjectId(con.Id);
if(!list_Attachment.isEmpty()) mail.setFileAttachments(list_Attachment);
emails.add(mail);