使用POP3协议接收并解析电子邮件（全）

package org.yangxin.study.jm;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Properties;

import javax.mail.Address;
import javax.mail.BodyPart;
import javax.mail.Flags;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.Part;
import javax.mail.Session;
import javax.mail.Store;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.internet.MimeUtility;

/**
 * 使用POP3协议接收邮件
 */
public class POP3ReceiveMailTest {

	public static void main(String[] args) throws Exception {
		receive();
	}

	/**
	 * 接收邮件
	 */
	public static void receive() throws Exception {
		// 准备连接服务器的会话信息
		Properties props = new Properties();
		props.setProperty("mail.store.protocol", "pop3");		// 协议
		props.setProperty("mail.pop3.port", "110");				// 端口
		props.setProperty("mail.pop3.host", "pop3.163.com");	// pop3服务器

		// 创建Session实例对象
		Session session = Session.getInstance(props);
		Store store = session.getStore("pop3");
		store.connect("xyang0917@163.com", "123456abc");

		// 获得收件箱
		Folder folder = store.getFolder("INBOX");
		/* Folder.READ_ONLY：只读权限
		 * Folder.READ_WRITE：可读可写（可以修改邮件的状态）
		 */
		folder.open(Folder.READ_WRITE);	//打开收件箱

		// 由于POP3协议无法获知邮件的状态,所以getUnreadMessageCount得到的是收件箱的邮件总数
		System.out.println("未读邮件数: " + folder.getUnreadMessageCount());

		// 由于POP3协议无法获知邮件的状态,所以下面得到的结果始终都是为0
		System.out.println("删除邮件数: " + folder.getDeletedMessageCount());
		System.out.println("新邮件: " + folder.getNewMessageCount());

		// 获得收件箱中的邮件总数
		System.out.println("邮件总数: " + folder.getMessageCount());

		// 得到收件箱中的所有邮件,并解析
		Message[] messages = folder.getMessages();
		parseMessage(messages);

		//释放资源
		folder.close(true);
		store.close();
	}

	/**
	 * 解析邮件
	 * @param messages 要解析的邮件列表
	 */
	public static void parseMessage(Message ...messages) throws MessagingException, IOException {
		if (messages == null || messages.length < 1)
			throw new MessagingException("未找到要解析的邮件!");

		// 解析所有邮件
		for (int i = 0, count = messages.length; i < count; i++) {
			MimeMessage msg = (MimeMessage) messages[i];
			System.out.println("------------------解析第" + msg.getMessageNumber() + "封邮件-------------------- ");
			System.out.println("主题: " + getSubject(msg));
			System.out.println("发件人: " + getFrom(msg));
			System.out.println("收件人：" + getReceiveAddress(msg, null));
			System.out.println("发送时间：" + getSentDate(msg, null));
			System.out.println("是否已读：" + isSeen(msg));
			System.out.println("邮件优先级：" + getPriority(msg));
			System.out.println("是否需要回执：" + isReplySign(msg));
			System.out.println("邮件大小：" + msg.getSize() * 1024 + "kb");
			boolean isContainerAttachment = isContainAttachment(msg);
			System.out.println("是否包含附件：" + isContainerAttachment);
			if (isContainerAttachment) {
				saveAttachment(msg, "c:\\mailtmp\\"+msg.getSubject() + "_"); //保存附件
			}
			StringBuffer content = new StringBuffer(30);
			getMailTextContent(msg, content);
			System.out.println("邮件正文：" + (content.length() > 100 ? content.substring(0,100) + "..." : content));
			System.out.println("------------------第" + msg.getMessageNumber() + "封邮件解析结束-------------------- ");
			System.out.println();
		}
	}

	/**
	 * 获得邮件主题
	 * @param msg 邮件内容
	 * @return 解码后的邮件主题
	 */
	public static String getSubject(MimeMessage msg) throws UnsupportedEncodingException, MessagingException {
		return MimeUtility.decodeText(msg.getSubject());
	}

	/**
	 * 获得邮件发件人
	 * @param msg 邮件内容
	 * @return 姓名 <Email地址>
	 * @throws MessagingException
	 * @throws UnsupportedEncodingException
	 */
	public static String getFrom(MimeMessage msg) throws MessagingException, UnsupportedEncodingException {
		String from = "";
		Address[] froms = msg.getFrom();
		if (froms.length < 1)
			throw new MessagingException("没有发件人!");

		InternetAddress address = (InternetAddress) froms[0];
		String person = address.getPersonal();
		if (person != null) {
			person = MimeUtility.decodeText(person) + " ";
		} else {
			person = "";
		}
		from = person + "<" + address.getAddress() + ">";

		return from;
	}

	/**
	 * 根据收件人类型，获取邮件收件人、抄送和密送地址。如果收件人类型为空，则获得所有的收件人
	 * <p>Message.RecipientType.TO  收件人</p>
	 * <p>Message.RecipientType.CC  抄送</p>
	 * <p>Message.RecipientType.BCC 密送</p>
	 * @param msg 邮件内容
	 * @param type 收件人类型
	 * @return 收件人1 <邮件地址1>, 收件人2 <邮件地址2>, ...
	 * @throws MessagingException
	 */
	public static String getReceiveAddress(MimeMessage msg, Message.RecipientType type) throws MessagingException {
		StringBuffer receiveAddress = new StringBuffer();
		Address[] addresss = null;
		if (type == null) {
			addresss = msg.getAllRecipients();
		} else {
			addresss = msg.getRecipients(type);
		}

		if (addresss == null || addresss.length < 1)
			throw new MessagingException("没有收件人!");
		for (Address address : addresss) {
			InternetAddress internetAddress = (InternetAddress)address;
			receiveAddress.append(internetAddress.toUnicodeString()).append(",");
		}

		receiveAddress.deleteCharAt(receiveAddress.length()-1);	//删除最后一个逗号

		return receiveAddress.toString();
	}

	/**
	 * 获得邮件发送时间
	 * @param msg 邮件内容
	 * @return yyyy年mm月dd日 星期X HH:mm
	 * @throws MessagingException
	 */
	public static String getSentDate(MimeMessage msg, String pattern) throws MessagingException {
		Date receivedDate = msg.getSentDate();
		if (receivedDate == null)
			return "";

		if (pattern == null || "".equals(pattern))
			pattern = "yyyy年MM月dd日 E HH:mm ";

		return new SimpleDateFormat(pattern).format(receivedDate);
	}

	/**
	 * 判断邮件中是否包含附件
	 * @param msg 邮件内容
	 * @return 邮件中存在附件返回true，不存在返回false
	 * @throws MessagingException
	 * @throws IOException
	 */
	public static boolean isContainAttachment(Part part) throws MessagingException, IOException {
		boolean flag = false;
		if (part.isMimeType("multipart/*")) {
			MimeMultipart multipart = (MimeMultipart) part.getContent();
			int partCount = multipart.getCount();
			for (int i = 0; i < partCount; i++) {
				BodyPart bodyPart = multipart.getBodyPart(i);
				String disp = bodyPart.getDisposition();
				if (disp != null && (disp.equalsIgnoreCase(Part.ATTACHMENT) || disp.equalsIgnoreCase(Part.INLINE))) {
					flag = true;
				} else if (bodyPart.isMimeType("multipart/*")) {
					flag = isContainAttachment(bodyPart);
				} else {
					String contentType = bodyPart.getContentType();
					if (contentType.indexOf("application") != -1) {
						flag = true;
					}  

					if (contentType.indexOf("name") != -1) {
						flag = true;
					}
				}

				if (flag) break;
			}
		} else if (part.isMimeType("message/rfc822")) {
			flag = isContainAttachment((Part)part.getContent());
		}
		return flag;
	}

	/**
	 * 判断邮件是否已读
	 * @param msg 邮件内容
	 * @return 如果邮件已读返回true,否则返回false
	 * @throws MessagingException
	 */
	public static boolean isSeen(MimeMessage msg) throws MessagingException {
		return msg.getFlags().contains(Flags.Flag.SEEN);
	}

	/**
	 * 判断邮件是否需要阅读回执
	 * @param msg 邮件内容
	 * @return 需要回执返回true,否则返回false
	 * @throws MessagingException
	 */
	public static boolean isReplySign(MimeMessage msg) throws MessagingException {
		boolean replySign = false;
		String[] headers = msg.getHeader("Disposition-Notification-To");
		if (headers != null)
			replySign = true;
		return replySign;
	}

	/**
	 * 获得邮件的优先级
	 * @param msg 邮件内容
	 * @return 1(High):紧急  3:普通(Normal)  5:低(Low)
	 * @throws MessagingException
	 */
	public static String getPriority(MimeMessage msg) throws MessagingException {
		String priority = "普通";
		String[] headers = msg.getHeader("X-Priority");
		if (headers != null) {
			String headerPriority = headers[0];
			if (headerPriority.indexOf("1") != -1 || headerPriority.indexOf("High") != -1)
				priority = "紧急";
			else if (headerPriority.indexOf("5") != -1 || headerPriority.indexOf("Low") != -1)
				priority = "低";
			else
				priority = "普通";
		}
		return priority;
	} 

	/**
	 * 获得邮件文本内容
	 * @param part 邮件体
	 * @param content 存储邮件文本内容的字符串
	 * @throws MessagingException
	 * @throws IOException
	 */
	public static void getMailTextContent(Part part, StringBuffer content) throws MessagingException, IOException {
		//如果是文本类型的附件，通过getContent方法可以取到文本内容，但这不是我们需要的结果，所以在这里要做判断
		boolean isContainTextAttach = part.getContentType().indexOf("name") > 0;
		if (part.isMimeType("text/*") && !isContainTextAttach) {
			content.append(part.getContent().toString());
		} else if (part.isMimeType("message/rfc822")) {
			getMailTextContent((Part)part.getContent(),content);
		} else if (part.isMimeType("multipart/*")) {
			Multipart multipart = (Multipart) part.getContent();
			int partCount = multipart.getCount();
			for (int i = 0; i < partCount; i++) {
				BodyPart bodyPart = multipart.getBodyPart(i);
				getMailTextContent(bodyPart,content);
			}
		}
	}

	/**
	 * 保存附件
	 * @param part 邮件中多个组合体中的其中一个组合体
	 * @param destDir  附件保存目录
	 * @throws UnsupportedEncodingException
	 * @throws MessagingException
	 * @throws FileNotFoundException
	 * @throws IOException
	 */
	public static void saveAttachment(Part part, String destDir) throws UnsupportedEncodingException, MessagingException,
			FileNotFoundException, IOException {
		if (part.isMimeType("multipart/*")) {
			Multipart multipart = (Multipart) part.getContent();	//复杂体邮件
			//复杂体邮件包含多个邮件体
			int partCount = multipart.getCount();
			for (int i = 0; i < partCount; i++) {
				//获得复杂体邮件中其中一个邮件体
				BodyPart bodyPart = multipart.getBodyPart(i);
				//某一个邮件体也有可能是由多个邮件体组成的复杂体
				String disp = bodyPart.getDisposition();
				if (disp != null && (disp.equalsIgnoreCase(Part.ATTACHMENT) || disp.equalsIgnoreCase(Part.INLINE))) {
					InputStream is = bodyPart.getInputStream();
					saveFile(is, destDir, decodeText(bodyPart.getFileName()));
				} else if (bodyPart.isMimeType("multipart/*")) {
					saveAttachment(bodyPart,destDir);
				} else {
					String contentType = bodyPart.getContentType();
					if (contentType.indexOf("name") != -1 || contentType.indexOf("application") != -1) {
						saveFile(bodyPart.getInputStream(), destDir, decodeText(bodyPart.getFileName()));
					}
				}
			}
		} else if (part.isMimeType("message/rfc822")) {
			saveAttachment((Part) part.getContent(),destDir);
		}
	}

	/**
	 * 读取输入流中的数据保存至指定目录
	 * @param is 输入流
	 * @param fileName 文件名
	 * @param destDir 文件存储目录
	 * @throws FileNotFoundException
	 * @throws IOException
	 */
	private static void saveFile(InputStream is, String destDir, String fileName)
			throws FileNotFoundException, IOException {
		BufferedInputStream bis = new BufferedInputStream(is);
		BufferedOutputStream bos = new BufferedOutputStream(
				new FileOutputStream(new File(destDir + fileName)));
		int len = -1;
		while ((len = bis.read()) != -1) {
			bos.write(len);
			bos.flush();
		}
		bos.close();
		bis.close();
	}

	/**
	 * 文本解码
	 * @param encodeText 解码MimeUtility.encodeText(String text)方法编码后的文本
	 * @return 解码后的文本
	 * @throws UnsupportedEncodingException
	 */
	public static String decodeText(String encodeText) throws UnsupportedEncodingException {
		if (encodeText == null || "".equals(encodeText)) {
			return "";
		} else {
			return MimeUtility.decodeText(encodeText);
		}
	}
}

测试结果：

获取邮件UID：

URLName url = new URLName("pop3", host, port, "", user, password);
Session session = Session.getInstance(System.getProperties(),null);
Store store = session.getStore(url);
POP3Folder inbox = null;
try {
       store.connect();
       inbox = (POP3Folder) store.getFolder("INBOX");
       inbox.open(Folder.READ_ONLY);
       FetchProfile profile = new FetchProfile();
       profile.add(UIDFolder.FetchProfileItem.UID);
       Message[] messages = inbox.getMessages();
       inbox.fetch(messages, profile);
       for (int i = 0; i < messages.length; i++)
              System.out.println(inbox.getUID(messages[i]));
} finally {
       try{
              inbox.close(false);
       }catch(Exception e){}
       try{
              store.close();
       }catch(Exception e){}
}