使用 MimeMultipart、Java 8 发送带有多个嵌入图像的邮件

Posted 2023-03-15

【中文标题】使用 MimeMultipart、Java 8 发送带有多个嵌入图像的邮件

【英文标题】：sending mail with multiple embedded images using MimeMultipart, Java 8

【发布时间】：2020-04-05 07:29:29

【问题描述】：

我正在尝试发送在正文中嵌入了多个图像的邮件.... 我正在回复这个Sending mail along with embedded image using javamail，但不幸的是我无法获得作品

创建消息

javax.mail.Message message = new javax.mail.internet.MimeMessage(Session.getInstance(mailingSettings.getProperties()));
message.setFrom(new InternetAddress(mailingSettings.getCorreoOrigen(), mailingSettings.getNombreOrigen()));
message.setSentDate(new Date());
message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(mailDTO.getCorreoDestino()));
message.addHeader("Content-type", "text/html; charset=iso-8859-1");
message.addHeader("Content-Transfer-Encoding", "8bit");
message.setSubject(mailDTO.getAsunto() + mailDTO.getCodigoDocumento() + "-sendOneMail");

现在我创建 Multipart

MimeMultipart multipart = new MimeMultipart();

// Ini Add the Body
BodyPart mimeBodyPart = new PreencodedMimeBodyPart("8bit");
mimeBodyPart.setContent(contenidoCorreo /*The HTML with multiple images*/, "text/html");
multipart.addBodyPart(mimeBodyPart);
// End Add the Body


addImages2(mailDTO, multipart, contenidoCorreo);
try 
  message.setContent(multipart);        //Add the Multipart to the Message 
  Transport.send(message);              //Send the Message
 catch (Exception e) 
  e.printStackTrace();
  throw e;

现在将图像添加到 Multipart 的方法

  private void addImages2(MailDTO mailDTO, final Multipart multipart, String contenidoCorreo) throws Exception 
    //Check the 'cid' words and get the image names....

    Set<String> setImagenes = Arrays.stream(contenidoCorreo.split("cid:")).collect(Collectors.toSet());
    setImagenes.stream().forEach(stringCid -> 
      String imagenCid = (stringCid.split("\""))[0];
      String pathImage = /path/to/Images/Directory + "/" + imagenCid;
      if (new File(pathImage).exists()) 
        BodyPart imagenMimeBodyPart = new MimeBodyPart();
        try 
          DataSource source = new FileDataSource(pathImage);
          imagenMimeBodyPart.setDataHandler(new DataHandler(source));
          imagenMimeBodyPart.setFileName(imagenCid);
          imagenMimeBodyPart.setHeader("Content-ID", imagenCid);
          multipart.addBodyPart(imagenMimeBodyPart);
         catch (Exception e) 
          e.printStackTrace();
        
      
    );

  

所有图片都像附件一样发送，但不会插入 HTML。

现在，我将使用成功的 Telnet 方法比较内容消息...

在左侧使用 Telnet 直接方法，在右侧我的 Java 代码。

将初始 sn-p 与 HTML 正文内容进行比较 比较 HTML Body Content 的最终 sn-p 左侧使用 Telnet 方法分离部分图像 使用 Telnet 方法的最后一部分！

带有附加图像的电子邮件

如何修复我的代码以显示插入到我的 HTML 代码中的图像并且图像也会显示？

【参考方案1】：

我扩展了 java 邮件类来添加和阅读附件， 您必须根据自己的目的修改代码，但它会在电子邮件中附加一个文件。我确实认为您不能附加原始二进制图像，它必须在发送之前转换为 base64 内联编码。并在收到时解码。

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 …..