使用MimeMultipart，Java 8发送带有多个嵌入式图像的邮件

我扩展了Java邮件类，以添加和阅读附件，您将需要修改代码以实现目的，但是它将文件附加到电子邮件中。我确实认为您无法附加原始二进制图像，必须先将其转换为base64内联编码，然后再发送。并在收到后解码。

public class Mail extends javax.mail.Authenticator {
private String _user;
private String _pass;

private String[] _to;
private String _from;

private String _port;
private String _sport;

private String _host;

private String _subject;
private String _body;

private boolean _auth;

private boolean _debuggable;

private Multipart _multipart;


public Mail() {
    _host = "smtp.gmail.com"; // default smtp server
    _port = "465"; // default smtp port
    _sport = "465"; // default socketfactory port

    _user = ""; // username
    _pass = ""; // password
    _from = ""; // email sent from
    _subject = ""; // email subject
    _body = ""; // email body

    _debuggable = false; // debug mode on or off - default off
    _auth = true; // smtp authentication - default on

    _multipart = new MimeMultipart();

    // There is something wrong with MailCap, javamail can not find a handler for the multipart/mixed part, so this bit needs to be added.
    MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap();
    mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
    mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
    mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
    mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
    mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
    CommandMap.setDefaultCommandMap(mc);
}

public Mail(String user, String pass) {
    this();

    _user = user;
    _pass = pass;
}

public String GetMail(){
    try {

        Properties props = System.getProperties();
        String mailhost = "imap.gmail.com";
        Session session;
        Store store;
        if (props == null){
            //Log.e(DEBUG, "Properties are null !!");
        }else{
            props.setProperty("mail.store.protocol", "imaps");

            /*Log.d(TAG, "Transport: "+props.getProperty("mail.transport.protocol"));
            Log.d(TAG, "Store: "+props.getProperty("mail.store.protocol"));
            Log.d(TAG, "Host: "+props.getProperty("mail.imap.host"));
            Log.d(TAG, "Authentication: "+props.getProperty("mail.imap.auth"));
            Log.d(TAG, "Port: "+props.getProperty("mail.imap.port"));*/
        }
        try {
            session = Session.getDefaultInstance(props, null);
            store = session.getStore("imaps");
            store.connect(mailhost, _user, _pass);
            //Log.i(TAG, "Store: "+store.toString());
            //create the folder object and open it
            Folder emailFolder = store.getFolder("INBOX");
            emailFolder.open(Folder.READ_ONLY);

            // retrieve the messages from the folder in an array and print it
            Message[] messages = emailFolder.getMessages();
            String contentType = messages[messages.length-1].getContentType();
            String messageContent = "";

            // store attachment file name, separated by comma
            String attachFiles = "";

            if (contentType.contains("multipart")) {
                // content may contain attachments
                Multipart multiPart = (Multipart) messages[messages.length-1].getContent();
                int numberOfParts = multiPart.getCount();
                for (int partCount = 0; partCount < numberOfParts; partCount++) {
                    MimeBodyPart part = (MimeBodyPart) multiPart.getBodyPart(partCount);
                    if (Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition())) {
                        InputStream is = part.getInputStream();

                        byte[] buf = new byte[1024];
                        Arrays.fill(buf, (byte) 0);
                        int bytesRead;
                        bytesRead =is.read(buf);
                        byte[] nBuf = new byte[bytesRead];
                        for (int i = 0; i < bytesRead; i++) {
                            nBuf[i] = buf[i];
                        }


                        //byte[bytesRead] bytearr = buf;
                        //fos.write(buf, 0, bytesRead);
                        if ( bytesRead > 0 ) {
                            String sBuf = new String(nBuf,"UTF-8");
                            int test = 0;
                            return ( sBuf );
                        }

                        // this part is attachment
                        String fileName = part.getFileName();
                        attachFiles += fileName + ", ";
                        //part.saveFile(saveDirectory + File.separator + fileName);
                    } else {
                        // this part may be the message content
                        messageContent = part.getContent().toString();
                    }
                }

                if (attachFiles.length() > 1) {
                    attachFiles = attachFiles.substring(0, attachFiles.length() - 2);
                }
            } else if (contentType.contains("text/plain")
                    || contentType.contains("text/html")) {
                Object content = messages[0].getContent();
                if (content != null) {
                    messageContent = content.toString();
                }
            }

            return( messages[0].getSubject());
        }  catch (MessagingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }



    } catch  (Exception e) {
        e.printStackTrace();
    }
    String nullstring ="";
    return( nullstring);
}
public boolean send() throws Exception {
    Properties props = _setProperties();

    if(!_user.equals("") && !_pass.equals("") && _to.length > 0 && !_from.equals("") && !_subject.equals("") && !_body.equals("")) {
        Session session = Session.getInstance(props, this);
        Log.e("MailApp", "session started");
        final MimeMessage msg = new MimeMessage(session);
        Log.e("MailApp", "mime");
        msg.setFrom(new InternetAddress(_from));
        Log.e("MailApp", "setfrom");
        InternetAddress[] addressTo = new InternetAddress[_to.length];
        for (int i = 0; i < _to.length; i++) {
            addressTo[i] = new InternetAddress(_to[i]);
        }
        msg.setRecipients(MimeMessage.RecipientType.TO, addressTo);

        msg.setSubject(_subject);
        msg.setSentDate(new Date());

        // setup message body
        BodyPart messageBodyPart = new MimeBodyPart();
        messageBodyPart.setText(_body);
        _multipart.addBodyPart(messageBodyPart);

        // Put parts in message
        msg.setContent(_multipart);

        Thread thread = new Thread(new Runnable(){
            @Override
            public void run() {
                try {
                    Transport.send(msg);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        thread.start();


        return true;
    } else {
        return false;
    }
}

public void addAttachment(String filename) throws Exception {
    BodyPart messageBodyPart = new MimeBodyPart();
    DataSource source = new FileDataSource(filename);
    messageBodyPart.setDataHandler(new DataHandler(source));
    messageBodyPart.setFileName(filename);

    _multipart.addBodyPart(messageBodyPart);
}

@Override
public PasswordAuthentication getPasswordAuthentication() {
    return new PasswordAuthentication(_user, _pass);
}

private Properties _setProperties() {
    Properties props = new Properties();

    props.put("mail.smtp.host", _host);

    if(_debuggable) {
        props.put("mail.debug", "true");
    }

    if(_auth) {
        props.put("mail.smtp.auth", "true");
    }

    props.put("mail.smtp.port", _port);
    props.put("mail.smtp.socketFactory.port", _sport);
    props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.socketFactory.fallback", "false");

    return props;
}

// the getters and setters
public String getBody() {
    return _body;
}

public void setBody(String _body) {
    this._body = _body;
}
public void setFrom( String _from ){
    this._from = _from;
}
public void setSubject( String _subject ){
    this._subject = _subject;
}
public void setTo( String[] _to ){
    this._to = _to;
}
// more of the getters and setters …..
}