用Java下载邮件附件

download mail attachment with Java

提问by Dónal

I had a look in the reference doc, and Spring seems to have pretty good support for sending mail. However, I need to login to a mail account, read the messages, and download any attachments. Is downloading mail attachments supported by the Spring mail API?

我查看了参考文档，Spring 似乎对发送邮件有很好的支持。但是，我需要登录邮件帐户、阅读邮件并下载任何附件。Spring 邮件 API 是否支持下载邮件附件？

I know you can do this with the Java Mail API, but in the past I've found that very verbose and unpleasant to work with.

我知道您可以使用 Java Mail API 做到这一点，但在过去，我发现使用它非常冗长且令人不快。

EDIT: I've received several replies pointing towards tutorials that describe how to send mail with attachments, but what I'm asking about is how to readattachments from receivedmail.

编辑：我收到了一些回复，指向描述如何发送带有附件的邮件的教程，但我要问的是如何从收到的邮件中读取附件。

Cheers, Don

干杯，唐

采纳答案by Steven M. Cherry

Here's the class that I use for downloading e-mails (with attachment handling). You'll have to glance by some of the stuff it's doing (like ignore the logging classes and database writes). I've also re-named some of the packages for ease of reading.

这是我用于下载电子邮件的类（带有附件处理）。您必须查看它正在执行的一些操作（例如忽略日志记录类和数据库写入）。为了便于阅读，我还重新命名了一些软件包。

The general idea is that all attachments are saved as individual files in the filesystem, and each e-mail is saved as a record in the database with a set of child records that point to all of the attachment file paths.

总体思路是，所有附件都保存为文件系统中的单个文件，并且每封电子邮件都保存为数据库中的一条记录，其中包含一组指向所有附件文件路径的子记录。

Focus on the doEMailDownload method.

专注于 doEMailDownload 方法。

/**
  * Copyright (c) 2008 Steven M. Cherry
  * All rights reserved.
  */
package utils.scheduled;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.sql.Timestamp;
import java.util.Properties;
import java.util.Vector;

import javax.mail.Address;
import javax.mail.Flags;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Multipart;
import javax.mail.Part;
import javax.mail.Session;
import javax.mail.Store;
import javax.mail.internet.MimeBodyPart;

import glob.ActionLogicImplementation;
import glob.IOConn;
import glob.log.Log;
import logic.utils.sql.Settings;
import logic.utils.sqldo.EMail;
import logic.utils.sqldo.EMailAttach;

/**
  * This will connect to our incoming e-mail server and download any e-mails
  * that are found on the server.  The e-mails will be stored for further processing
  * in our internal database.  Attachments will be written out to separate files
  * and then referred to by the database entries.  This is intended to be  run by 
  * the scheduler every minute or so.
  *
  * @author Steven M. Cherry
  */
public class DownloadEMail implements ActionLogicImplementation {

    protected String receiving_host;
    protected String receiving_user;
    protected String receiving_pass;
    protected String receiving_protocol;
    protected boolean receiving_secure;
    protected String receiving_attachments;

    /** This will run our logic */
    public void ExecuteRequest(IOConn ioc) throws Exception {
        Log.Trace("Enter");

        Log.Debug("Executing DownloadEMail");
        ioc.initializeResponseDocument("DownloadEMail");

        // pick up our configuration from the server:
        receiving_host = Settings.getValue(ioc, "server.email.receiving.host");
        receiving_user = Settings.getValue(ioc, "server.email.receiving.username");
        receiving_pass = Settings.getValue(ioc, "server.email.receiving.password");
        receiving_protocol = Settings.getValue(ioc, "server.email.receiving.protocol");
        String tmp_secure = Settings.getValue(ioc, "server.email.receiving.secure");
        receiving_attachments = Settings.getValue(ioc, "server.email.receiving.attachments");

        // sanity check on the parameters:
        if(receiving_host == null || receiving_host.length() == 0){
            ioc.SendReturn();
            ioc.Close();
            Log.Trace("Exit");
            return; // no host defined.
        }
        if(receiving_user == null || receiving_user.length() == 0){
            ioc.SendReturn();
            ioc.Close();
            Log.Trace("Exit");
            return; // no user defined.
        }
        if(receiving_pass == null || receiving_pass.length() == 0){
            ioc.SendReturn();
            ioc.Close();
            Log.Trace("Exit");
            return; // no pass defined.
        }
        if(receiving_protocol == null || receiving_protocol.length() == 0){
            Log.Debug("EMail receiving protocol not defined, defaulting to POP");
            receiving_protocol = "POP";
        }
        if(tmp_secure == null || 
            tmp_secure.length() == 0 ||
            tmp_secure.compareToIgnoreCase("false") == 0 ||
            tmp_secure.compareToIgnoreCase("no") == 0
        ){
            receiving_secure = false;
        } else {
            receiving_secure = true;
        }
        if(receiving_attachments == null || receiving_attachments.length() == 0){
            Log.Debug("EMail receiving attachments not defined, defaulting to ./email/attachments/");
            receiving_attachments = "./email/attachments/";
        }

        // now do the real work.
        doEMailDownload(ioc);

        ioc.SendReturn();
        ioc.Close();
        Log.Trace("Exit");
    }

    protected void doEMailDownload(IOConn ioc) throws Exception {
        // Create empty properties
        Properties props = new Properties();
        // Get the session
        Session session = Session.getInstance(props, null);

        // Get the store
        Store store = session.getStore(receiving_protocol);
        store.connect(receiving_host, receiving_user, receiving_pass);

        // Get folder
        Folder folder = store.getFolder("INBOX");
        folder.open(Folder.READ_WRITE);

        try {

            // Get directory listing
            Message messages[] = folder.getMessages();

            for (int i=0; i < messages.length; i++) {
                // get the details of the message:
                EMail email = new EMail();
                email.fromaddr = messages[i].getFrom()[0].toString();
                Address[] to = messages[i].getRecipients(Message.RecipientType.TO);
                email.toaddr = "";
                for(int j = 0; j < to.length; j++){
                    email.toaddr += to[j].toString() + "; ";
                }
                Address[] cc;
                try {
                    cc = messages[i].getRecipients(Message.RecipientType.CC);
                } catch (Exception e){
                    Log.Warn("Exception retrieving CC addrs: %s", e.getLocalizedMessage());
                    cc = null;
                }
                email.cc = "";
                if(cc != null){
                    for(int j = 0; j < cc.length; j++){
                        email.cc += cc[j].toString() + "; ";
                    }
                }
                email.subject = messages[i].getSubject();
                if(messages[i].getReceivedDate() != null){
                    email.received_when = new Timestamp(messages[i].getReceivedDate().getTime());
                } else {
                    email.received_when = new Timestamp( (new java.util.Date()).getTime());
                }


                email.body = "";
                Vector<EMailAttach> vema = new Vector<EMailAttach>();
                Object content = messages[i].getContent();
                if(content instanceof java.lang.String){
                    email.body = (String)content;
                } else if(content instanceof Multipart){
                    Multipart mp = (Multipart)content;

                    for (int j=0; j < mp.getCount(); j++) {
                        Part part = mp.getBodyPart(j);

                        String disposition = part.getDisposition();

                        if (disposition == null) {
                            // Check if plain
                            MimeBodyPart mbp = (MimeBodyPart)part;
                            if (mbp.isMimeType("text/plain")) {
                                Log.Debug("Mime type is plain");
                                email.body += (String)mbp.getContent();
                            } else {
                                Log.Debug("Mime type is not plain");
                                // Special non-attachment cases here of 
                                // image/gif, text/html, ...
                                EMailAttach ema = new EMailAttach();
                                ema.name = decodeName(part.getFileName());
                                File savedir = new File(receiving_attachments);
                                savedir.mkdirs();
                                File savefile = File.createTempFile("emailattach", ".atch", savedir );
                                ema.path = savefile.getAbsolutePath();
                                ema.size = part.getSize();
                                vema.add(ema);
                                ema.size = saveFile(savefile, part);
                            }
                        } else if ((disposition != null) && 
                            (disposition.equals(Part.ATTACHMENT) || disposition.equals(Part.INLINE) ) 
                        ){
                            // Check if plain
                            MimeBodyPart mbp = (MimeBodyPart)part;
                            if (mbp.isMimeType("text/plain")) {
                                Log.Debug("Mime type is plain");
                                email.body += (String)mbp.getContent();
                            } else {
                                Log.Debug("Save file (%s)", part.getFileName() );
                                EMailAttach ema = new EMailAttach();
                                ema.name = decodeName(part.getFileName());
                                File savedir = new File(receiving_attachments);
                                savedir.mkdirs();
                                File savefile = File.createTempFile("emailattach", ".atch", savedir );
                                ema.path = savefile.getAbsolutePath();
                                ema.size = part.getSize();
                                vema.add(ema);
                                ema.size = saveFile( savefile, part);
                            }
                        }
                    }
                }

                // Insert everything into the database:
                logic.utils.sql.EMail.insertEMail(ioc, email);
                for(int j = 0; j < vema.size(); j++){
                    vema.get(j).emailid = email.id;
                    logic.utils.sql.EMail.insertEMailAttach(ioc, vema.get(j) );
                }

                // commit this message and all of it's attachments
                ioc.getDBConnection().commit();

                // Finally delete the message from the server.
                messages[i].setFlag(Flags.Flag.DELETED, true);
            }

            // Close connection 
            folder.close(true); // true tells the mail server to expunge deleted messages.
            store.close();
        } catch (Exception e){
            folder.close(true); // true tells the mail server to expunge deleted messages.
            store.close();
            throw e;
        }

    }

    protected int saveFile(File saveFile, Part part) throws Exception {

        BufferedOutputStream bos = new BufferedOutputStream( new FileOutputStream(saveFile) );

        byte[] buff = new byte[2048];
        InputStream is = part.getInputStream();
        int ret = 0, count = 0;
        while( (ret = is.read(buff)) > 0 ){
            bos.write(buff, 0, ret);
            count += ret;
        }
        bos.close();
        is.close();
        return count;
    }

    protected String decodeName( String name ) throws Exception {
        if(name == null || name.length() == 0){
            return "unknown";
        }
        String ret = java.net.URLDecoder.decode( name, "UTF-8" );

        // also check for a few other things in the string:
        ret = ret.replaceAll("=\?utf-8\?q\?", "");
        ret = ret.replaceAll("\?=", "");
        ret = ret.replaceAll("=20", " ");

        return ret;
    }

}

回答by Steve Moyer

Thus far, I've only used the JavaMail APIs (and I've been reasonably happy with them for my purposes). If the full JavaMail package is too heavy for you, the underlying transport engine can be used without the top layers of the package. The lower you go in the SMTP, POP3 and IMAP stacks, the more you have to be prepared to do for yourself.

到目前为止，我只使用了 JavaMail API（并且对于我的目的，我对它们相当满意）。如果完整的 JavaMail 包对您来说太重了，那么可以在没有包的顶层的情况下使用底层传输引擎。您在 SMTP、POP3 和 IMAP 堆栈中的位置越低，您需要为自己做的准备就越多。

On the bright side, you'll also be able to ignore the parts that aren't required for your application.

从好的方面来说，您还可以忽略应用程序不需要的部分。

回答by Maciej Kreft

Here is an error:

这是一个错误：

else if ((disposition != null) && (disposition.equals(Part.ATTACHMENT)
 || disposition.equals(Part.INLINE) ) 

it should be:

它应该是：

else if ((disposition.equalsIgnoreCase(Part.ATTACHMENT)
 || disposition.equalsIgnoreCase(Part.INLINE))

Thanks @Stevenmcherry for your answer

感谢@Stevenmcherry 的回答

回答by chad

I worked Steven's example a little bit and removed the parts of the code specific to Steven. My code won't read the body of an email if it has attachments. That is fine for my case but you may want to refine it further for yours.

我对史蒂文的例子做了一点工作，并删除了特定于史蒂文的代码部分。如果有附件，我的代码将不会读取电子邮件的正文。这对我的情况很好，但您可能想为您的情况进一步完善它。

package utils;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Properties;

import javax.mail.Address;
import javax.mail.Flags;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Multipart;
import javax.mail.Part;
import javax.mail.Session;
import javax.mail.Store;
import javax.mail.internet.MimeBodyPart;

public class IncomingMail {

 public static List<Email> downloadPop3(String host, String user, String pass, String downloadDir) throws Exception {

  List<Email> emails = new ArrayList<Email>();

  // Create empty properties
  Properties props = new Properties();

  // Get the session
  Session session = Session.getInstance(props, null);

  // Get the store
  Store store = session.getStore("pop3");
  store.connect(host, user, pass);

  // Get folder
  Folder folder = store.getFolder("INBOX");
  folder.open(Folder.READ_WRITE);

  try {
   // Get directory listing
   Message messages[] = folder.getMessages();
   for (int i = 0; i < messages.length; i++) {

    Email email = new Email();

    // from 
    email.from = messages[i].getFrom()[0].toString();

    // to list
    Address[] toArray = messages[i] .getRecipients(Message.RecipientType.TO);
    for (Address to : toArray) { email.to.add(to.toString()); }

    // cc list
    Address[] ccArray = null;
    try {
     ccArray = messages[i] .getRecipients(Message.RecipientType.CC);
    } catch (Exception e) { ccArray = null; }
    if (ccArray != null) {
     for (Address c : ccArray) {
      email.cc.add(c.toString());
     }
    }

    // subject
    email.subject = messages[i].getSubject();

    // received date
    if (messages[i].getReceivedDate() != null) {
     email.received = messages[i].getReceivedDate();
    } else {
     email.received = new Date();
    }

    // body and attachments
    email.body = "";
    Object content = messages[i].getContent();
    if (content instanceof java.lang.String) {

     email.body = (String) content;

    } else if (content instanceof Multipart) {

     Multipart mp = (Multipart) content;

     for (int j = 0; j < mp.getCount(); j++) {

      Part part = mp.getBodyPart(j);
      String disposition = part.getDisposition();

      if (disposition == null) {

       MimeBodyPart mbp = (MimeBodyPart) part;
       if (mbp.isMimeType("text/plain")) {
        // Plain
        email.body += (String) mbp.getContent();
       } 

      } else if ((disposition != null) && (disposition.equals(Part.ATTACHMENT) || disposition .equals(Part.INLINE))) {

       // Check if plain
       MimeBodyPart mbp = (MimeBodyPart) part;
       if (mbp.isMimeType("text/plain")) {
        email.body += (String) mbp.getContent();
       } else {
        EmailAttachment attachment = new EmailAttachment();
        attachment.name = decodeName(part.getFileName());
        File savedir = new File(downloadDir);
        savedir.mkdirs();
        // File savefile = File.createTempFile( "emailattach", ".atch", savedir);
        File savefile = new File(downloadDir,attachment.name);
        attachment.path = savefile.getAbsolutePath();
        attachment.size = saveFile(savefile, part);
        email.attachments.add(attachment);
       }
      }
     } // end of multipart for loop 
    } // end messages for loop

    emails.add(email);

    // Finally delete the message from the server.
    messages[i].setFlag(Flags.Flag.DELETED, true);
   }

   // Close connection
   folder.close(true); // true tells the mail server to expunge deleted messages
   store.close();

  } catch (Exception e) {
   folder.close(true); // true tells the mail server to expunge deleted
   store.close();
   throw e;
  }

  return emails;
 }

 private static String decodeName(String name) throws Exception {
  if (name == null || name.length() == 0) {
   return "unknown";
  }
  String ret = java.net.URLDecoder.decode(name, "UTF-8");

  // also check for a few other things in the string:
  ret = ret.replaceAll("=\?utf-8\?q\?", "");
  ret = ret.replaceAll("\?=", "");
  ret = ret.replaceAll("=20", " ");

  return ret;
 }

 private static int saveFile(File saveFile, Part part) throws Exception {

  BufferedOutputStream bos = new BufferedOutputStream(
    new FileOutputStream(saveFile));

  byte[] buff = new byte[2048];
  InputStream is = part.getInputStream();
  int ret = 0, count = 0;
  while ((ret = is.read(buff)) > 0) {
   bos.write(buff, 0, ret);
   count += ret;
  }
  bos.close();
  is.close();
  return count;
 }

}

You also need these two helper classes

你还需要这两个辅助类

package utils;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class Email {

 public Date received;
 public String from;
 public List<String> to = new ArrayList<String>();
 public List<String> cc = new ArrayList<String>();
 public String subject;
 public String body;
 public List<EmailAttachment> attachments = new ArrayList<EmailAttachment>();
}

and

和

package utils;

public class EmailAttachment {

 public String name;
 public String path;
 public int size;
}

I used this to test the above classes

我用它来测试上述类

package utils;

import java.util.List;


public class Test {

 public static void main(String[] args) {

  String host = "some host";
  String user = "some user";
  String pass = "some pass";
  String downloadDir = "/Temp";
  try {
   List<Email> emails = IncomingMail.downloadPop3(host, user, pass, downloadDir);
   for ( Email email : emails ) {
    System.out.println(email.from);
    System.out.println(email.subject);
    System.out.println(email.body);
    List<EmailAttachment> attachments = email.attachments;
    for ( EmailAttachment attachment : attachments ) {
     System.out.println(attachment.path+" "+attachment.name);
    }
   }
  } catch (Exception e) { e.printStackTrace(); }

 }

}

More info can be found at http://java.sun.com/developer/onlineTraining/JavaMail/contents.html

更多信息可以在http://java.sun.com/developer/onlineTraining/JavaMail/contents.html找到

回答by Karthik Reddy

import java.io.IOException;
import java.io.InputStream;

import javax.mail.internet.MimeMessage;
import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.InputStreamSource;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.mail.javamail.MimeMessagePreparator;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.commons.CommonsMultipartFile;

@Controller
@RequestMapping("/sendEmail.do")
public class SendEmailAttachController {
    @Autowired
    private JavaMailSender mailSender;

    @RequestMapping(method = RequestMethod.POST)
    public String sendEmail(HttpServletRequest request,
            final @RequestParam CommonsMultipartFile attachFile) {

        // Input here
        final String emailTo = request.getParameter("mailTo");
        final String subject = request.getParameter("subject");
        final String yourmailid = request.getParameter("yourmail");
        final String message = request.getParameter("message");

        // Logging
        System.out.println("emailTo: " + emailTo);
        System.out.println("subject: " + subject);
        System.out.println("Your mail id is: "+yourmailid);
        System.out.println("message: " + message);
        System.out.println("attachFile: " + attachFile.getOriginalFilename());

        mailSender.send(new MimeMessagePreparator() {

            @Override
            public void prepare(MimeMessage mimeMessage) throws Exception {
                MimeMessageHelper messageHelper = new MimeMessageHelper(
                        mimeMessage, true, "UTF-8");
                messageHelper.setTo(emailTo);
                messageHelper.setSubject(subject);
                messageHelper.setReplyTo(yourmailid);
                messageHelper.setText(message);

                // Attachment with mail
                String attachName = attachFile.getOriginalFilename();
                if (!attachFile.equals("")) {

                    messageHelper.addAttachment(attachName, new InputStreamSource() {

                        @Override
                        public InputStream getInputStream() throws IOException {
                            return attachFile.getInputStream();
                        }
                    });
                }

            }

        });

        return "Result";
    }
}

回答by Faber

I used Apache Commons Mail for this task:

我使用 Apache Commons Mail 来完成这个任务：

import java.util.List;
import javax.activation.DataSource; 
import javax.mail.internet.MimeMessage;   
import org.apache.commons.mail.util.MimeMessageParser;   

public List<DataSource> getAttachmentList(MimeMessage message) throws Exception {
    msgParser = new MimeMessageParser(message);
    msgParser.parse();
    return msgParser.getAttachmentList();
}

From a DataSourceobject you can retrieve an InputStream(beside name and type) of the attachment (see API: http://docs.oracle.com/javase/6/docs/api/javax/activation/DataSource.html?is-external=true).

从DataSource对象中，您可以检索InputStream附件的（除了名称和类型之外）（请参阅 API：http: //docs.oracle.com/javase/6/docs/api/javax/activation/DataSource.html?is-external=真的）。