常用的类：
1.     javax.mail.Session;                                                    -------->保存连接服务器所需要的信息；
2.     javax.mail.Message;                                                  -------->邮件体，保存邮件的内容；
3.     javax.mail.Transport;                                                 -------->发送邮件的载体
4.     javax.mail.internet.InternetAddress;                         -------->邮件的地址信息

import java.util.Properties; import javax.mail.Address;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage; /** * * QQ(mail.qq.com):POP3服务器（端口995）SMTP服务器（端口465或587）。 * */
public class Demo1 { /** * @param args * @throws MessagingException */public static void main(String[] args) throws MessagingException { String sendUserName = "wangxiangpan@126.com"; String sendPassword = "pwd"; Properties properties = new Properties(); properties.setProperty("mail.smtp.auth", "true");//服务器需要认证 properties.setProperty("mail.transport.protocol", "smtp");//声明发送邮件使用的端口
      Session session = Session.getInstance(properties); session.setDebug(true);//同意在当前线程的控制台打印与服务器对话信息
      Message message = new MimeMessage(session);//构建发送的信息 message.setText("你好，我是Champion.Wong！");//信息内容 message.setFrom(new InternetAddress("wangxiangpan@126.com"));//发件人
      Transport transport = session.getTransport(); transport.connect("smtp.126.com", 25, sendUserName, sendPassword);//连接发件人使用发件的服务器 transport.sendMessage(message, new Address[]{new InternetAddress("492134880@qq.com")});//接受邮件
    transport.close(); } } 

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.MimeMessage; import junit.framework.TestCase; /** * javamail 发送邮件 * @author Champion Wong * Message.addRecipient(Message.Recipient recipient, Address address); 发邮件的时候指定收件人和收件人的角色 * Message.RecipientType.TO 收件人 * Message.RecipientType.CC 抄送，即发邮件的时候顺便给另一个人抄一份，不用回复！但是，上边的收件人可以看到你都抄送给了谁 * Message.RecipientType.BCC 暗送，也是发邮件的时候顺便给另一个人暗发一份，但是，不同于上边的是，收件人不能看到你都暗送给了谁 * */
public class Demo2 extends TestCase { private static final String sendUserName = "wangxiangpan@126.com";// 发送邮件需要连接的服务器的用户名 private static final String sendPassword = "pwd";// 发送邮件需要连接的服务器的密码 private static final String sendProtocol = "smtp";// 发送邮件使用的端口 private static final String sendHostAddress = "smtp.126.com";// 发送邮件使用的服务器的地址 public void test() throws AddressException, MessagingException { Properties properties = new Properties(); properties.setProperty("mail.smtp.auth", "true");// 服务器需要认证 properties.setProperty("mail.transport.protocol", sendProtocol);// 声明发送邮件使用的端口 properties.setProperty("mail.host", sendHostAddress);// 发送邮件的服务器地址
  Session session = Session.getInstance(properties, new Authenticator() { protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication(sendUserName, sendPassword); } }); session.setDebug(true);//在后台打印发送邮件的实时信息
  Message message = new MimeMessage(session); message.setFrom(new InternetAddress("wangxiangpan@126.com")); message.setSubject("Demo2JavaCode发送邮件测试，采用Authenticator");// 设置主题
    message.setRecipients(Message.RecipientType.TO, InternetAddress .parse("492134880@qq.com,wangxiangpan@126.com"));// 发送
    message.setRecipients(Message.RecipientType.CC, InternetAddress .parse("msn_wangxiangpan@hotmail.com"));// 抄送
    message .setContent( "<span style="font-size:20px; color:#FFCCFF" mce_style="font-size:20px; color:#FFCCFF">如果您看到，证明测试成功了！</span>", "text/html;charset=gbk"); Transport.send(message);//发送邮件
  }
} 

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Properties; import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.Authenticator;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.Message.RecipientType;
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; /** * * @author Administrator Mr XP.Wang * MimeMultipart 一般电子邮件的容器是Multipart，定义了增加及删除电子邮件各部分内容的方法， *        但是其是抽象类，需要其子类MimeMultipart来时用MimeMessage对象 * MimeBodyPart 是BodyPart具体用于mimeMessage的一个子类，MimeBodyPart对象代表一个 *       mimeMultipart对象的每一个部分 * MimeUtility.encodeText(String cn)用于解决邮件中的头部信息中中文的乱码问题 * */
public class Demo3_test { public static void main(String[] args) throws Exception { Properties properties = new Properties(); properties.setProperty("mail.smtp.auth", "true");// 服务器需要认证 properties.setProperty("mail.transport.protocol", "smtp");// 声明发送邮件使用的端口 properties.setProperty("mail.host", "smtp.126.com");// 发送邮件的服务器地址
      Session session = Session.getInstance(properties, new Authenticator() { String sendUserName = "wangxiangpan@126.com"; String sendPassword = "pwd"; protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication(sendUserName, sendPassword); } }); session.setDebug(true); MimeMessage msg = new MimeMessage(session);// 声明一个邮件体 msg.setFrom(new InternetAddress("/""+MimeUtility.encodeText("Mr XP.Wang")+"/"<wangxiangpan@126.com>")); msg.setSubject("这是我的第一份复杂邮件");//设置邮件主题 msg.setRecipients(MimeMessage.RecipientType.TO, InternetAddress.parse(MimeUtility.encodeText("王翔攀")+"<wangxiangpan@126.com>,"+MimeUtility.encodeText("三毛")+"<492134880@qq.com>")); MimeMultipart msgMultipart = new MimeMultipart("mixed");// 标明邮件的组合关系，混合的关系 msg.setContent(msgMultipart);// 设置邮件体
      MimeBodyPart attch1 = new MimeBodyPart();// 附件1 MimeBodyPart attch2 = new MimeBodyPart();// 附件2 MimeBodyPart content = new MimeBodyPart();// 邮件的正文，混合体（图片+文字） // 将附件和正文设置到这个邮件体中
    msgMultipart.addBodyPart(attch1); msgMultipart.addBodyPart(attch2); msgMultipart.addBodyPart(content); // 设置第一个附件 DataSource ds1 = new FileDataSource("F:/ACCP5.0/文件/ssh配置.txt");// 指定附件的数据源 DataHandler dh1 = new DataHandler(ds1);// 附件的信息 attch1.setDataHandler(dh1);// 指定附件 attch1.setFileName("ssh.txt"); // 设置第二个附件 DataSource ds2 = new FileDataSource("resource/48.jpg");// 指定附件的数据源 DataHandler dh2 = new DataHandler(ds2);// 附件的信息 attch2.setDataHandler(dh2);// 指定附件 attch2.setFileName("48.jpg"); //设置邮件的正文 MimeMultipart bodyMultipart = new MimeMultipart("related");//依赖关系 content.setContent(bodyMultipart);//指定正文 MimeBodyPart htmlPart = new MimeBodyPart(); MimeBodyPart gifPart = new MimeBodyPart(); bodyMultipart.addBodyPart(htmlPart); bodyMultipart.addBodyPart(gifPart); DataSource gifds = new FileDataSource("resource/48.jpg");//正文的图片 DataHandler gifdh = new DataHandler(gifds); gifPart.setHeader("Content-Location", "http://mimg.126.net/logo/126logo.gif"); gifPart.setDataHandler(gifdh);//设置正文的图片
      htmlPart.setContent("我只是来打酱油的，这是我的形象照！<img src="/" mce_src="/""http://mimg.126.net/logo/126logo.gif/">", "text/html;charset=gbk");//设置正文文字
      msg.saveChanges();//保存邮件 //将邮件保存成文件 OutputStream ops = new FileOutputStream("C:/Users/Administrator/Desktop/test.eml"); msg.writeTo(ops); ops.close(); Transport.send(msg); } } 

import java.util.Date;
import java.util.Properties;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.Session;
import javax.mail.Store;public class FetchMail {public static void main(String[] args) {String protocol = "pop3";boolean isSSL = true;String host = "pop.163.com";int port = 995;String username = "rose@163.com";String password = "rose";Properties props = new Properties();props.put("mail.pop3.ssl.enable", isSSL);props.put("mail.pop3.host", host);props.put("mail.pop3.port", port);Session session = Session.getDefaultInstance(props);Store store = null;Folder folder = null;try {store = session.getStore(protocol);store.connect(username, password);folder = store.getFolder("INBOX");folder.open(Folder.READ_ONLY);int size = folder.getMessageCount();Message message = folder.getMessage(size);String from = message.getFrom()[0].toString();String subject = message.getSubject();Date date = message.getSentDate();System.out.println("From: " + from);System.out.println("Subject: " + subject);System.out.println("Date: " + date);} catch (NoSuchProviderException e) {e.printStackTrace();} catch (MessagingException e) {e.printStackTrace();} finally {try {if (folder != null) {folder.close(false);}if (store != null) {store.close();}} catch (MessagingException e) {e.printStackTrace();}}System.out.println("接收完毕！");}
}