JavaMail學習筆記（四）、使用POP3協議接收並解析電子郵件（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協議接收郵件
 */
public class POP3ReceiveMailTest {
	
	public static void main(String[] args) throws Exception {
		receive();
	}
	
	/**
	 * 接收郵件
	 */
	public static void receive() throws Exception {
		// 準備連線伺服器的會話資訊
		Properties props = new Properties();
		props.setProperty("mail.store.protocol", "pop3");		// 協議
		props.setProperty("mail.pop3.port", "110");				// 埠
		props.setProperty("mail.pop3.host", "pop3.163.com");	// pop3伺服器
		
		// 建立Session例項物件
		Session session = Session.getInstance(props);
		Store store = session.getStore("pop3");
		store.connect("xyang0917@163.com", "123456abc");
		
		// 獲得收件箱
		Folder folder = store.getFolder("INBOX");
		/* Folder.READ_ONLY：只讀許可權
		 * Folder.READ_WRITE：可讀可寫（可以修改郵件的狀態）
		 */
		folder.open(Folder.READ_WRITE);	//開啟收件箱
		
		// 由於POP3協議無法獲知郵件的狀態,所以getUnreadMessageCount得到的是收件箱的郵件總數
		System.out.println("未讀郵件數: " + folder.getUnreadMessageCount());
		
		// 由於POP3協議無法獲知郵件的狀態,所以下面得到的結果始終都是為0
		System.out.println("刪除郵件數: " + folder.getDeletedMessageCount());
		System.out.println("新郵件: " + folder.getNewMessageCount());
		
		// 獲得收件箱中的郵件總數
		System.out.println("郵件總數: " + folder.getMessageCount());
		
		// 得到收件箱中的所有郵件,並解析
		Message[] messages = folder.getMessages();
		parseMessage(messages);
		
		//釋放資源
		folder.close(true);
		store.close();
	}
	
	/**
	 * 解析郵件
	 * @param messages 要解析的郵件列表
	 */
	public static void parseMessage(Message ...messages) throws MessagingException, IOException {
		if (messages == null || messages.length < 1) 
			throw new MessagingException("未找到要解析的郵件!");
		
		// 解析所有郵件
		for (int i = 0, count = messages.length; i < count; i++) {
			MimeMessage msg = (MimeMessage) messages[i];
			System.out.println("------------------解析第" + msg.getMessageNumber() + "封郵件-------------------- ");
			System.out.println("主題: " + getSubject(msg));
			System.out.println("發件人: " + getFrom(msg));
			System.out.println("收件人：" + getReceiveAddress(msg, null));
			System.out.println("傳送時間：" + getSentDate(msg, null));
			System.out.println("是否已讀：" + isSeen(msg));
			System.out.println("郵件優先順序：" + getPriority(msg));
			System.out.println("是否需要回執：" + isReplySign(msg));
			System.out.println("郵件大小：" + 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() + "_"); //儲存附件
			} 
			StringBuffer content = new StringBuffer(30);
			getMailTextContent(msg, content);
			System.out.println("郵件正文：" + (content.length() > 100 ? content.substring(0,100) + "..." : content));
			System.out.println("------------------第" + msg.getMessageNumber() + "封郵件解析結束-------------------- ");
			System.out.println();
		}
	}
	
	/**
	 * 獲得郵件主題
	 * @param msg 郵件內容
	 * @return 解碼後的郵件主題
	 */
	public static String getSubject(MimeMessage msg) throws UnsupportedEncodingException, MessagingException {
		return MimeUtility.decodeText(msg.getSubject());
	}
	
	/**
	 * 獲得郵件發件人
	 * @param msg 郵件內容
	 * @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("沒有發件人!");
		
		InternetAddress address = (InternetAddress) froms[0];
		String person = address.getPersonal();
		if (person != null) {
			person = MimeUtility.decodeText(person) + " ";
		} else {
			person = "";
		}
		from = person + "<" + address.getAddress() + ">";
		
		return from;
	}
	
	/**
	 * 根據收件人型別，獲取郵件收件人、抄送和密送地址。如果收件人型別為空，則獲得所有的收件人
	 * <p>Message.RecipientType.TO  收件人</p>
	 * <p>Message.RecipientType.CC  抄送</p>
	 * <p>Message.RecipientType.BCC 密送</p>
	 * @param msg 郵件內容
	 * @param type 收件人型別
	 * @return 收件人1 <郵件地址1>, 收件人2 <郵件地址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("沒有收件人!");
		for (Address address : addresss) {
			InternetAddress internetAddress = (InternetAddress)address;
			receiveAddress.append(internetAddress.toUnicodeString()).append(",");
		}
		
		receiveAddress.deleteCharAt(receiveAddress.length()-1);	//刪除最後一個逗號
		
		return receiveAddress.toString();
	}
	
	/**
	 * 獲得郵件傳送時間
	 * @param msg 郵件內容
	 * @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);
	}
	
	/**
	 * 判斷郵件中是否包含附件
	 * @param msg 郵件內容
	 * @return 郵件中存在附件返回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;
	}
	
	/**
	 * 判斷郵件是否已讀
	 * @param msg 郵件內容
	 * @return 如果郵件已讀返回true,否則返回false
	 * @throws MessagingException 
	 */
	public static boolean isSeen(MimeMessage msg) throws MessagingException {
		return msg.getFlags().contains(Flags.Flag.SEEN);
	}
	
	/**
	 * 判斷郵件是否需要閱讀回執
	 * @param msg 郵件內容
	 * @return 需要回執返回true,否則返回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;
	}
	
	/**
	 * 獲得郵件的優先順序
	 * @param msg 郵件內容
	 * @return 1(High):緊急  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 = "緊急";
			else if (headerPriority.indexOf("5") != -1 || headerPriority.indexOf("Low") != -1)
				priority = "低";
			else
				priority = "普通";
		}
		return priority;
	} 
	
	/**
	 * 獲得郵件文字內容
	 * @param part 郵件體
	 * @param content 儲存郵件文字內容的字串
	 * @throws MessagingException
	 * @throws IOException
	 */
	public static void getMailTextContent(Part part, StringBuffer content) throws MessagingException, IOException {
		//如果是文字型別的附件，通過getContent方法可以取到文字內容，但這不是我們需要的結果，所以在這裡要做判斷
		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);
			}
		}
	}
	
	/**
	 * 儲存附件
	 * @param part 郵件中多個組合體中的其中一個組合體
	 * @param destDir  附件儲存目錄
	 * @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();	//複雜體郵件
			//複雜體郵件包含多個郵件體
			int partCount = multipart.getCount();
			for (int i = 0; i < partCount; i++) {
				//獲得複雜體郵件中其中一個郵件體
				BodyPart bodyPart = multipart.getBodyPart(i);
				//某一個郵件體也有可能是由多個郵件體組成的複雜體
				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);
		}
	}
	
	/**
	 * 讀取輸入流中的資料儲存至指定目錄
	 * @param is 輸入流
	 * @param fileName 檔名
	 * @param destDir 檔案儲存目錄
	 * @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();
	}
	
	/**
	 * 文字解碼
	 * @param encodeText 解碼MimeUtility.encodeText(String text)方法編碼後的文字
	 * @return 解碼後的文字
	 * @throws UnsupportedEncodingException
	 */
	public static String decodeText(String encodeText) throws UnsupportedEncodingException {
		if (encodeText == null || "".equals(encodeText)) {
			return "";
		} else {
			return MimeUtility.decodeText(encodeText);
		}
	}
}

測試結果：