Java Mail发送简单邮件，完整代码

依赖javax.mail.jar,地址：https://java.net/projects/javamail/pages/Home

完整示例代码如下：

package com.jadic.utils;

import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Properties;
import java.util.regex.Pattern;

import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.internet.MimeUtility;

/**
 * 简易邮件发送<br>
 * 需提供邮件服务提供商的smtp地址、邮箱账号、密码收件人邮箱<br><br>
 * 使用方式:<br>
 * 1.实例化JMail对象，适合多次利用相同账号信息发送到相同收件人<br>
 * &nbsp;&nbsp; JMail jMail = new JMail(...);<br>
 * &nbsp;&nbsp; jMail.sendMail(subject, content);<br>
 * 2.直接调用JMail静态方法发送，需每次都将smtp、账号、收件人、内容提供<br>
 * &nbsp;&nbsp; JMail.sendMail(smtp, fromUserAddress, fromUserPass,recipients,subject,content);
 * @author Jadic
 * @created 2014-5-13
 */
public class JMail {

    private String smtpHost;// smtp服务器地址
    private String userName;// 发送方账号
    private String userPass;// 发送方密码
    private List<String> recipientList;// 收件人列表

    private Message msg;
    private boolean isMailConfigInited;

    private final static String VALID_EMAIL_REGEX = "^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,6}$";
    private final static Pattern VALID_EMAIL_PATTERN = Pattern.compile(VALID_EMAIL_REGEX, Pattern.CASE_INSENSITIVE);

    private final static String SEND_MAIL_OK = "OK";
    private final static String SEND_MAIL_NO_RECIPIENTS = "Fail:no valid recipient set";

    private JMail(String smtp, String fromUserAddress, String fromUserPass) {
        this.smtpHost = smtp;
        this.userName = fromUserAddress;
        this.userPass = fromUserPass;

        recipientList = new ArrayList<String>();
        isMailConfigInited = false;
    }

    /**
     * @param smtp smtp服务地址
     * @param fromUserAddress  发件人邮箱账号
     * @param fromUserPass 发件人邮箱密码
     * @param recipient 收件人地址(列表),支持多个收件人以";"分割
     */
    public JMail(String smtp, String fromUserAddress, String fromUserPass, String recipient) {
        this(smtp, fromUserAddress, fromUserPass);
        String[] recs = recipient.split(";");
        for (String rec : recs) {
            if (isValidEmail(rec)) {
                this.recipientList.add(rec);
            }
        }
    }

    /**
     * @param smtp smtp服务地址
     * @param fromUserAddress 发件人邮箱账号
     * @param fromUserPass 发件人邮箱密码
     * @param recipients  收件人地址列表
     */
    public JMail(String smtp, String fromUserAddress, String fromUserPass, String... recipients) {
        this(smtp, fromUserAddress, fromUserPass);
        for (String recipient : recipients) {
            if (isValidEmail(recipient)) {
                this.recipientList.add(recipient);
            }
        }
    }

    /**
     * @param smtp smtp服务地址
     * @param fromUserAddress 发件人邮箱账号
     * @param fromUserPass 发件人邮箱密码
     * @param recipientList 收件人地址列表
     */
    public JMail(String smtp, String fromUserAddress, String fromUserPass, List<String> recipientList) {
        this(smtp, fromUserAddress, fromUserPass);
        for (String recipient : recipientList) {
            if (isValidEmail(recipient)) {
                this.recipientList.add(recipient);
            }
        }
    }

    /**
     * 发送邮件,主题默认"default"
     * @param content  发送内容
     * @return "ok" 成功发送，否则返回失败提示
     */
    public String sendMail(String content) {
        return sendMail("default", content);
    }

    /**
     * @param subject    邮件主题
     * @param content    邮件内容
     * @return "ok" 成功发送，否则返回失败提示
     */
    public String sendMail(String subject, String content) {
        if (this.recipientList.size() <= 0) {
            return SEND_MAIL_NO_RECIPIENTS;
        }

        if (!isMailConfigInited) {
            try {
                initMailConfig();
            } catch (AddressException e) {
                return "fail: address err[" + e.getMessage().trim() + "]";
            } catch (MessagingException e) {
                return "fail: MessagingErr[" + e.getMessage().trim() + "]";
            }
        }
        try {
            msg.setSentDate(new Date());
        } catch (MessagingException e) {
            e.printStackTrace();
        }
        try {
            msg.setSubject(MimeUtility.encodeText(subject, "gbk", "B"));

            MimeMultipart mmp = new MimeMultipart();
            MimeBodyPart mbp = new MimeBodyPart();
            mbp.setContent(content, "text/plain;charset=gbk");
            mmp.addBodyPart(mbp);
            msg.setContent(mmp);
            Transport.send(msg);
        } catch (UnsupportedEncodingException e) {
            return "fail: unsupported encoding[" + e.getMessage().trim() + "]";
        } catch (MessagingException e) {
            return "fail: MessagingErr[" + e.getMessage().trim() + "]";
        }

        return SEND_MAIL_OK;
    }

    private void initMailConfig() throws AddressException, MessagingException {
        Properties props = new Properties();
        // 发送服务器需要身份验证
        props.setProperty("mail.smtp.auth", "true");
        // 设置邮件服务器主机名
        props.setProperty("mail.host", smtpHost);
        // 发送邮件协议名称
        props.setProperty("mail.transport.protocol", "smtp");

        Session session = Session.getInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(userName, userPass);
            }
        });
        msg = new MimeMessage(session);
        msg.setFrom(new InternetAddress(userName));
        msg.addRecipients(Message.RecipientType.TO, getRecipients());
        isMailConfigInited = true;
    }

    /**
     * 
     * @param smtp    smtp地址
     * @param fromUserAddress 发件人账号
     * @param fromUserPass    发件人账号密码
     * @param recipients 收件人(列表),多个收件人以";"分割
     * @param subject 邮件主题
     * @param content 邮件内容
     * @return "ok" 成功发送，否则返回失败提示
     */
    public static String sendMail(String smtp, String fromUserAddress, String fromUserPass, String recipients, String subject,
            String content) {
        final String userName = fromUserAddress;
        final String userPass = fromUserPass;
        Properties props = new Properties();
        // 发送服务器需要身份验证
        props.setProperty("mail.smtp.auth", "true");
        // 设置邮件服务器主机名
        props.setProperty("mail.host", smtp);
        // 发送邮件协议名称
        props.setProperty("mail.transport.protocol", "smtp");

        Session session = Session.getInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(userName, userPass);
            }
        });
        Message msg = new MimeMessage(session);
        try {
            msg.setFrom(new InternetAddress(userName));
            String[] recipientAry = recipients.split(";");
            InternetAddress[] recipientsAddress = new InternetAddress[recipientAry.length];
            for (int i = 0; i < recipientAry.length; i++) {
                if (isValidEmail(recipientAry[i])) {
                    recipientsAddress[i] = new InternetAddress(recipientAry[i]);
                }
            }
            msg.addRecipients(Message.RecipientType.TO, recipientsAddress);
            msg.setSentDate(new Date());
            msg.setSubject(MimeUtility.encodeText(subject, "gbk", "B"));

            MimeMultipart mmp = new MimeMultipart();
            MimeBodyPart mbp = new MimeBodyPart();
            mbp.setContent(content, "text/plain;charset=gbk");
            mmp.addBodyPart(mbp);
            msg.setContent(mmp);
            Transport.send(msg);
        } catch (UnsupportedEncodingException e) {
            return "fail: unsupported encoding[" + e.getMessage().trim() + "]";
        } catch (MessagingException e) {
            return "fail: MessagingErr[" + e.getMessage().trim() + "]";
        }

        return SEND_MAIL_OK;
    }

    private InternetAddress[] getRecipients() throws AddressException {
        if (recipientList.size() > 0) {
            InternetAddress[] recipients = new InternetAddress[recipientList.size()];
            for (int i = 0; i < recipients.length; i++) {
                recipients[i] = new InternetAddress(this.recipientList.get(i));
            }
            return recipients;
        }
        return new InternetAddress[0];
    }

    private static boolean isValidEmail(String email) {
        return email != null && VALID_EMAIL_PATTERN.matcher(email).find();
    }
}