用Java下载邮件附件

本文介绍了用Java下载邮件附件的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

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支持下载邮件附件吗?

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.

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.

编辑:我收到了一些回复，这些回复都指向描述如何发送带附件的邮件的教程，但我要问的是如何阅读来自收到邮件.

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 read attachments from received mail.

干杯，唐

推荐答案

这是我用于下载电子邮件的类(带附件处理).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.

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.

总体思路是，所有附件都保存为文件系统中的单个文件，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.

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.

关注 doEMailDownload 方法.

Focus on the doEMailDownload method.

/** * 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_securepareToIgnoreCase("false") == 0 || tmp_securepareToIgnoreCase("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()mit(); // 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.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; } }