背景
我已经反对这一段时间了，并没有取得多大进展。我在Android中生成MPEG_4 / AAC文件，并通过电子邮件发送为.mp3文件。我知道它们实际上并不是.mp3文件，但允许Hotmail和Gmail在预览中播放它们。他们不会在iPhone上工作，除非他们以.m4a文件的形式发送，而不会破坏Outlook / Gmail预览。
所以我想到了一种不同的方法，即附加为.mp3文件，但在电子邮件正文中有一个HTML链接，允许下载附加文件并指定.m4a文件名。 Gmail / Outlook用户可以直接点击附件，而iPhone用户可以使用HTML链接。
问题
我可以使用带有HTML的JavaMail发送一封电子邮件，其中包含一个指向附件的链接，以便链接下载该文件。点击Gmail中的链接（Chrome上的Chrome）会显示404页面，iPhone会忽略我点击该链接。
下面是我生成多部分消息并为附件分配CID的代码，然后我尝试使用html部分中的链接访问该附件。感觉就像我很亲密，但也许这是一种幻觉。如果有人能帮助我解决问题或者在不可能的情况下拯救我的痛苦，我会非常感激。
private int send_email_temp(){
Properties props = new Properties();
props.put("mail.smtp.auth", "true");
props.put("mail.smtp.host", smtp_host_setting);
//props.put("mail.debug", "true");
props.put("mail.smtp.ssl.enable", "true");
props.put("mail.smtp.starttls.enable", "true");
props.put("mail.smtp.port", smtp_port_setting);
session = Session.getInstance(props);
ActuallySendAsync_temp asy = new ActuallySendAsync_temp(true);
asy.execute();
return 0;
}
class ActuallySendAsync_temp extends AsyncTask<String, String, Void> {
public ActuallySendAsync_temp(boolean boo) {
// something to do before sending email
}
@Override
protected Void doInBackground(String... params) {
try {
Message message = new MimeMessage(session);
message.setFrom(new InternetAddress(username));
message.setRecipients(Message.RecipientType.TO,
InternetAddress.parse(recipient_email_address));
message.setSubject(email_subject);
Multipart multipart = new MimeMultipart();
MimeBodyPart messageBodyPart = new MimeBodyPart();
String file = mFileName;
/**/
DataSource source = new FileDataSource(file);
messageBodyPart.setDataHandler(new DataHandler(source));
/* /
File ff = new File(file);
try {
messageBodyPart.attachFile(ff);
} catch(IOException eio) {
Log.e("Message Error", "Old Macdonald");
}
/* /
messageBodyPart = new PreencodedMimeBodyPart("base64");
byte[] file_bytes = null;
File ff = new File(file);
try {
int length = (int) ff.length();
BufferedInputStream reader = new BufferedInputStream(new FileInputStream(ff));
file_bytes = new byte[length];
reader.read(file_bytes, 0, length);
reader.close();
} catch (IOException eio) {
Log.e("Message Error", "Old Macdonald");
}
messageBodyPart.setText(Base64.encodeToString(file_bytes, Base64.DEFAULT));
messageBodyPart.setHeader("Content-Transfer-Encoding", "base64");
/**/
messageBodyPart.setFileName( DEFAULT_AUDIO_FILENAME );//"AudioClip.mp3");
//messageBodyPart.setContentID("<audio_clip>");
String content_id = UUID.randomUUID().toString();
messageBodyPart.setContentID("<" + content_id + ">");
messageBodyPart.setDisposition(Part.ATTACHMENT);//INLINE);
messageBodyPart.setHeader("Content-Type", "audio/mp4");
multipart.addBodyPart(messageBodyPart);
MimeBodyPart messageBodyText = new MimeBodyPart();
//final String MY_HTML_MESSAGE = "<h1>My HTML</h1><a download=\"AudioClip.m4a\" href=\"cid:audio_clip\">iPhone Download</a>";
final String MY_HTML_MESSAGE = "<h1>My HTML</h1><a download=\"AudioClip.m4a\" href=\"cid:" + content_id + "\">iPhone Download</a>";
messageBodyText.setContent( MY_HTML_MESSAGE, "text/html");
multipart.addBodyPart(messageBodyText);
message.setContent(multipart);
Print_Message_To_Console(message);
Transport transport = session.getTransport("smtp");
transport.connect(smtp_host_setting, username, password);
transport.sendMessage(message, message.getAllRecipients());
transport.close();
} catch (MessagingException e) {
e.printStackTrace();
} finally {
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
// something to do after sending email
}
}
int Print_Message_To_Console(Message msg) {
int ret_val = 0;
int line_num = 0;
InputStream in = null;
InputStreamReader inputStreamReader = null;
BufferedReader buff_reader = null;
try {
in = msg.getInputStream();
inputStreamReader = new InputStreamReader(in);
buff_reader = new BufferedReader(inputStreamReader);
String temp = "";
while ((temp = buff_reader.readLine()) != null) {
Log.d("Message Line " + Integer.toString(line_num++), temp);
}
} catch(Exception e) {
Log.d("Message Lines", "------------ OOPS! ------------");
ret_val = 1;
} finally {
try {
if (buff_reader != null) buff_reader.close();
if (inputStreamReader != null) inputStreamReader.close();
if (in != null) in.close();
} catch(Exception e2) {
Log.d("Message Lines", "----------- OOPS! 2 -----------");
ret_val = 2;
}
}
return ret_val;
}