呃，好吧，我只寫過三個(gè)JavaMail的程序。
都是批量郵件守護(hù)程序。決定總結(jié)一下，希望非常幸運(yùn)找到這篇文章的人不會(huì)再對(duì)這個(gè)困惑。
必須明白的基礎(chǔ)知識(shí)
- STMP協(xié)議是如何工作的
協(xié)議的標(biāo)準(zhǔn)在這里 http://www.ietf.org/rfc/rfc2821.txt?number=2821
下面是扼要說明（http://www.freesoft.org/CIE/Topics/94.htm ）：
Simple Mail Transfer Protocol (SMTP), documented in RFC
821, is Internet’s standard host-to-host mail transport protocol and
traditionally operates over TCP, port 25. In other words, a UNIX user
can type telnet hostname 25 and connect with an SMTP server, if one is
present.
SMTP uses a style of asymmetric request-response protocol popular in
the early 1980s, and still seen occasionally, most often in mail
protocols. The protocol is designed to be equally useful to either a
computer or a human, though not too forgiving of the human. From the
server’s viewpoint, a clear set of commands is provided and
well-documented in the RFC. For the human, all the commands are clearly
terminated by newlines and a HELP command lists all of them. From the
sender’s viewpoint, the command replies always take the form of text
lines, each starting with a three-digit code identifying the result of
the operation, a continuation character to indicate another lines
following, and then arbitrary text information designed to be
informative to a human.
事實(shí)上，你可以像使用DOS命令一樣發(fā)送電子郵件。http://bbs.stcore.com/archiver/tid-8024.htm 當(dāng)然因?yàn)楦鞣N原因，你的嘗試不可能成功。事實(shí)上SMTP工作的時(shí)候就是簡(jiǎn)單的發(fā)送命令。取得認(rèn)證，發(fā)送數(shù)據(jù)。得到反饋。確認(rèn)退出這么簡(jiǎn)單。
- SMTP中用于發(fā)送的數(shù)據(jù)
SMTP中發(fā)送的數(shù)據(jù)，遵從Multipurpose Internet Mail Extensions (MIME)標(biāo)準(zhǔn)，呃，我不得不說，這是這個(gè)星球上最重要的標(biāo)準(zhǔn)之一。所有的互聯(lián)網(wǎng)通信基本都是基于這個(gè)標(biāo)準(zhǔn)的演化。除了電子郵件，常見的應(yīng)用還包括HTTP報(bào)文等（也就是所有網(wǎng)頁(yè)了），另外即使在20年后發(fā)展的XML，其2進(jìn)制數(shù)據(jù)發(fā)送仍然實(shí)用的MIME中的編碼方式。
恩，這里就涉及到郵件附件如何處理的問題。恩，簡(jiǎn)單地說就是BASE64編碼
Table 1: The Base64 Alphabet
Value Encoding Value Encoding Value Encoding Value Encoding
0 A 17 R 34 i 51 z
1 B 18 S 35 j 52 0
2 C 19 T 36 k 53 1
3 D 20 U 37 l 54 2
4 E 21 V 38 m 55 3
5 F 22 W 39 n 56 4
6 G 23 X 40 o 57 5
7 H 24 Y 41 p 58 6
8 I 25 Z 42 q 59 7
9 J 26 a 43 r 60 8
10 K 27 b 44 s 61 9
11 L 28 c 45 t 62 +
12 M 29 d 46 u 63 /
13 N 30 e 47 v
14 O 31 f 48 w (pad) =
15 P 32 g 49 x
16 Q 33 h 50 y
在這種編碼中，我們將字符或者二進(jìn)制編碼以6個(gè)比特位為一組，替換成相應(yīng)的字符形式。比如
100110111010001011101001
轉(zhuǎn)換結(jié)果就是
100110 -> 38
111010 -> 58
001011 -> 11
101001 -> 41
38 -> m
58 -> 6
11 -> L
41 -> p
m6Lp
于是，我們就可以以文本的方式編碼二進(jìn)制流以及擴(kuò)展ASCII字符，比如中文字符。
基礎(chǔ)知識(shí)完畢，下面是FAQ
Java發(fā)送電子郵件需要哪些軟件包
mail.jar 通常還會(huì)需要 activation.jar
下載地址
http://java.sun.com/products/javabeans/jaf/downloads/index.html
https://maven-repository.dev.java.net/nonav/repository/javax.mail/
如何發(fā)送郵件
關(guān)于：
- 如何發(fā)送郵件
- 如何發(fā)送帶有附件的郵件
- 如何發(fā)送中文郵件
- 郵件中文標(biāo)題亂碼怎么辦
- 郵件附件亂碼怎么辦等等問題
請(qǐng)查看以下代碼
public static synchronized void sendMail(Properties settings)
throws Exception {
Properties props = new Properties();
props.put("mail.smtp.host", settings.get(StartCore.MAIL_SERVER));
props.put("mail.smtp.user", settings.get(StartCore.USER_NAME));
props.put("mail.smtp.auth", "true");
//SMTP服務(wù)器用戶驗(yàn)證
Authenticator auth = new SMTPAuthenticator((String) settings
.get(StartCore.USER_NAME), (String) settings
.get(StartCore.PASSWORD));
Session session = Session.getDefaultInstance(props, auth);
if ("true".compareToIgnoreCase((String) settings.get("DEBUG")) == 0) {
session.setDebug(true);
}
//創(chuàng)建消息體
MimeMessage msg = new MimeMessage(session);
//設(shè)置發(fā)送人郵件
msg.setFrom(new InternetAddress((String) settings
.get(StartCore.USER_MAIL)));
//設(shè)置接收人郵件
address = new InternetAddress[] { new InternetAddress(rs
.getString("GRE_mail")) };
msg.setRecipients(Message.RecipientType.TO, address);
//設(shè)置主題，中文編碼
msg.setSubject(subject, "gbk");
msg.setSentDate(new Date());
String content = "郵件正文";
MimeBodyPart mbp1 = new MimeBodyPart();
mbp1.setText(content, "gbk");
//郵件附件
MimeBodyPart attachFilePart = new MimeBodyPart();
File file = new File("中文附件.txt");
FileDataSource fds = new FileDataSource(file.getName());
attachFilePart.setDataHandler(new DataHandler(fds));
sun.misc.BASE64Encoder enc = new sun.misc.BASE64Encoder();
//解決中文附件名稱
attachFilePart.setFileName("=?gbk?B?"
+ enc.encode(file.getName().getBytes("gbk")) + "?=");
Multipart mp = new MimeMultipart();
mp.addBodyPart(mbp1);
mp.addBodyPart(attachFilePart);
msg.setContent(mp);
// send the message
msg.saveChanges();
Transport.send(msg);
}
這是上面用戶驗(yàn)證用到的類
class SMTPAuthenticator extends javax.mail.Authenticator {
private String username;
private String password;
/**
* @param username
* @param password
*/
public SMTPAuthenticator(String username, String password) {
this.username = username;
this.password = password;
}
public PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(username, password);
}
}
郵件發(fā)送出錯(cuò)
What causes an
“javax.activation.UnsupportedDataTypeException: no object DCH for MIME
type xxx/xxxx javax.mail.MessagingException: IOException while sending
message;” to be sent and how do I fix this? [This happens for known
MIME types like text/htm
事實(shí)上這個(gè)是郵件發(fā)送時(shí)驗(yàn)證組件設(shè)置不當(dāng)引起的，這個(gè)組件配置方法如下
(http://java.sun.com/j2ee/1.4/docs/api/javax/activation/MailcapCommandMap.html)
The MailcapCommandMap looks in various places in the user’s system
for mailcap file entries. When requests are made to search for commands
in the MailcapCommandMap, it searches mailcap files in the following
order:
1) Programatically added entries to the MailcapCommandMap instance.
2) The file .mailcap in the user’s home directory.
3) The file /lib/mailcap.
4) The file or resources named META-INF/mailcap.
5) The file or resource named META-INF/mailcap.default (usually found only in the activation.jar file).
我選用了第四種方法，在生成的Jar文件中加入了 META-INF/mailcap.
#
# This is a very simple 'mailcap' file
#
image/gif;; x-java-view=com.sun.activation.viewers.ImageViewer
image/jpeg;; x-java-view=com.sun.activation.viewers.ImageViewer
text/*;; x-java-view=com.sun.activation.viewers.TextViewer
text/*;; x-java-edit=com.sun.activation.viewers.TextEditor
text/html;; x-java-content-handler=com.sun.mail.handlers.text_html
text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml
text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain
multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed
message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822