使用javamail发送html邮件比较复杂

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package org.tatan.mail;

import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeUtility;
import javax.mail.Session;
import javax.mail.MessagingException;
import javax.mail.Transport;

public class SendHtmlMail {
    public static void sendMessage(String smtpHost,
                                   String from, String to,
                                   String subject, String messageText)
            throws MessagingException,java.io.UnsupportedEncodingException {

        // Step 1:  Configure the mail session
        System.out.println("Configuring mail session for: " + smtpHost);
        java.util.Properties props = new java.util.Properties();
        props.setProperty("mail.smtp.auth", "true");//指定是否需要SMTP验证
        props.setProperty("mail.smtp.host", smtpHost);//指定SMTP服务器
        props.put("mail.transport.protocol", "smtp");
        Session mailSession = Session.getDefaultInstance(props);
        mailSession.setDebug(true);//是否在控制台显示debug信息

        // Step 2:  Construct the message
        System.out.println("Constructing message -  from=" + from + "  to=" + to);
        InternetAddress fromAddress = new InternetAddress(from);
        InternetAddress toAddress = new InternetAddress(to);

        MimeMessage testMessage = new MimeMessage(mailSession);
        testMessage.setFrom(fromAddress);
        testMessage.addRecipient(javax.mail.Message.RecipientType.TO, toAddress);
        testMessage.setSentDate(new java.util.Date());
        testMessage.setSubject(MimeUtility.encodeText(subject,"gb2312","B"));

        testMessage.setContent(messageText, "text/html;charset=gb2312");
        System.out.println("Message constructed");

        // Step 3:  Now send the message
        Transport transport = mailSession.getTransport("smtp");
        transport.connect(smtpHost, "webmaster", "password");
        transport.sendMessage(testMessage, testMessage.getAllRecipients());
        transport.close();

        System.out.println("Message sent!");
    }

    public static void main(String[] args) {

        String smtpHost = "localhost";
        String from = "webmaster@mymail.com";
        String to = "mfc42d@sohu.com";
        String subject = "html邮件测试"; //subject javamail自动转码

        StringBuffer theMessage = new StringBuffer();
        theMessage.append("<h2><font color=red>这倒霉孩子</font></h2>");
        theMessage.append("<hr>");
        theMessage.append("<i>年年失望年年望</i>");

        try {
            SendHtmlMail.sendMessage(smtpHost, from, to, subject, theMessage.toString());
        }
        catch (javax.mail.MessagingException exc) {
            exc.printStackTrace();
        }
        catch (java.io.UnsupportedEncodingException exc) {
            exc.printStackTrace();
        }
    }
}
邮件头(参见RFC822，RFC2047)只能包含US-ASCII字符。
邮件头中任何包含非US-ASCII字符的部分必须进行编码，使其只包含US-ASCII字符。
但是java mail可以根据JVM发送中文邮件自行编码，，用它自带的MimeUtility类的encodeText方法对中文信息进行编码也可以。
邮件正文必须有charset=gb2312否则为
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit
打开邮件为乱码,设置charset=gb2312后
Content-Type: text/html;charset=gb2312
Content-Transfer-Encoding: quoted-printable
它不能用MimeUtility里的方法来编码。
邮件正文的编码方式的信息是要放在Content-Transfer-Encoding这个邮件头参数中的，
而MimeUtility里面的方法是将编码方式的信息放在编码后的正文内容中。
所以如果你对正文也用MimeUtility进行处理，那么其他邮件程序就不会正常显示你编码的邮件，
因为其他邮件软件如outlook,foxmail只会根据Content-Transfer-Encoding这个里面的信息来对邮件正文进行解码。