关键技术：
- javax.mail.Store：该类实现特定邮件协议（如POP3）上的读、写、监视、查找等操作。通过它的getFolder方法打开一个javax.mail.Folder。
- javax.mail.Folder：该类用于描述邮件的分级组织，如收件箱、草稿箱。它的open方法打开分级组织，close方法关闭分级组织，getMessages方法获得分级组织中的邮件，getNewMessageCount方法获得分级组织中新邮件的数量，getUnreadMessageCount方法获得分级组织中未读邮件的数量
- 根据MimeMessage的getFrom和getRecipients方法获得邮件的发件人和收件人地址列表，得到的是InternetAddress数组，根据InternetAddress的getAddress方法获得邮件地址，根据InternetAddress的getPersonal方法获得邮件地址的个人信息。
- MimeMessage的getSubject、getSentDate、getMessageID方法获得邮件的主题、发送日期和邮件的ID（表示邮件）。
- 通过MimeMessage的getContent方法获得邮件的内容，如果邮件是MIME邮件，那么得到的是一个Multipart的对象，如果是一共普通的文本邮件，那么得到的是BodyPart对象。Multipart可以包含多个BodyPart，而BodyPart本身又可以是Multipart。BodyPart的MimeType类型为“multipart/*”时，表示它是一个Mutipart。
- 但一个BodyPart的disposition属性等于Part.ATTACHMENT或者Part.INLINE常量时，表示它带有附件。通过BodyPart的getInputStream方法可以获得附件的输入流。
package book.email;
import java.io.File;
import java.util.Properties;
/**
* 收邮件的基本信息
*/
public class MailReceiverInfo {
// 邮件服务器的IP、端口和协议
private String mailServerHost;
private String mailServerPort = "110";
private String protocal = "pop3";
// 登陆邮件服务器的用户名和密码
private String userName;
private String password;
// 保存邮件的路径
private String attachmentDir = "C:/temp/";
private String emailDir = "C:/temp/";
private String emailFileSuffix = ".eml";
// 是否需要身份验证
private boolean validate = true;
/**
* 获得邮件会话属性
*/
public Properties getProperties(){
Properties p = new Properties();
p.put("mail.pop3.host", this.mailServerHost);
p.put("mail.pop3.port", this.mailServerPort);
p.put("mail.pop3.auth", validate ? "true" : "false");
return p;
}
public String getProtocal() {
return protocal;
}
public void setProtocal(String protocal) {
this.protocal = protocal;
}
public String getAttachmentDir() {
return attachmentDir;
}
public void setAttachmentDir(String attachmentDir) {
if (!attachmentDir.endsWith(File.separator)){
attachmentDir = attachmentDir + File.separator;
}
this.attachmentDir = attachmentDir;
}
public String getEmailDir() {
return emailDir;
}
public void setEmailDir(String emailDir) {
if (!emailDir.endsWith(File.separator)){
emailDir = emailDir + File.separator;
}
this.emailDir = emailDir;
}
public String getEmailFileSuffix() {
return emailFileSuffix;
}
public void setEmailFileSuffix(String emailFileSuffix) {
if (!emailFileSuffix.startsWith(".")){
emailFileSuffix = "." + emailFileSuffix;
}
this.emailFileSuffix = emailFileSuffix;
}
public String getMailServerHost() {
return mailServerHost;
}
public void setMailServerHost(String mailServerHost) {
this.mailServerHost = mailServerHost;
}
public String getMailServerPort() {
return mailServerPort;
}
public void setMailServerPort(String mailServerPort) {
this.mailServerPort = mailServerPort;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public boolean isValidate() {
return validate;
}
public void setValidate(boolean validate) {
this.validate = validate;
}
}
package book.email;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;
import java.util.Date;
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.NoSuchProviderException;
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.MimeUtility;
/**
* 邮件接收器，目前支持pop3协议。
* 能够接收文本、HTML和带有附件的邮件
*/
public class MailReceiver {
// 收邮件的参数配置
private MailReceiverInfo receiverInfo;
// 与邮件服务器连接后得到的邮箱
private Store store;
// 收件箱
private Folder folder;
// 收件箱中的邮件消息
private Message[] messages;
// 当前正在处理的邮件消息
private Message currentMessage;
private String currentEmailFileName;
public MailReceiver(MailReceiverInfo receiverInfo) {
this.receiverInfo = receiverInfo;
}
/**
* 收邮件
*/
public void receiveAllMail() throws Exception{
if (this.receiverInfo == null){
throw new Exception("必须提供接收邮件的参数！");
}
// 连接到服务器
if (this.connectToServer()) {
// 打开收件箱
if (this.openInBoxFolder()) {
// 获取所有邮件
this.getAllMail();
this.closeConnection();
} else {
throw new Exception("打开收件箱失败！");
}
} else {
throw new Exception("连接邮件服务器失败！");
}
}
/**
* 登陆邮件服务器
*/
private boolean connectToServer() {
// 判断是否需要身份认证
MyAuthenticator authenticator = null;
if (this.receiverInfo.isValidate()) {
// 如果需要身份认证，则创建一个密码验证器
authenticator = new MyAuthenticator(this.receiverInfo.getUserName(),
this.receiverInfo.getPassword());
}
//创建session
Session session = Session.getInstance(this.receiverInfo
.getProperties(), authenticator);
//创建store,建立连接
try {
this.store = session.getStore(this.receiverInfo.getProtocal());
} catch (NoSuchProviderException e) {
System.out.println("连接服务器失败！");
return false;
}
System.out.println("connecting");
try {
this.store.connect();
} catch (MessagingException e) {
System.out.println("连接服务器失败！");
return false;
}
System.out.println("连接服务器成功");
return true;
}
/**
* 打开收件箱
*/
private boolean openInBoxFolder() {
try {
this.folder = store.getFolder("INBOX");
// 只读
folder.open(Folder.READ_ONLY);
return true;
} catch (MessagingException e) {
System.err.println("打开收件箱失败！");
}
return false;
}
/**
* 断开与邮件服务器的连接
*/
private boolean closeConnection() {
try {
if (this.folder.isOpen()) {
this.folder.close(true);
}
this.store.close();
System.out.println("成功关闭与邮件服务器的连接！");
return true;
} catch (Exception e) {
System.out.println("关闭和邮件服务器之间连接时出错！");
}
return false;
}
/**
* 获取messages中的所有邮件
* @throws MessagingException
*/
private void getAllMail() throws MessagingException {
//从邮件文件夹获取邮件信息
this.messages = this.folder.getMessages();
System.out.println("总的邮件数目：" + messages.length);
System.out.println("新邮件数目：" + this.getNewMessageCount());
System.out.println("未读邮件数目：" + this.getUnreadMessageCount());
//将要下载的邮件的数量。
int mailArrayLength = this.getMessageCount();
System.out.println("一共有邮件" + mailArrayLength + "封");
int errorCounter = 0; //邮件下载出错计数器
int successCounter = 0;
for (int index = 0; index < mailArrayLength; index++) {
try {
this.currentMessage = (messages[index]); //设置当前message
System.out.println("正在获取第" + index + "封邮件
");
this.showMailBasicInfo();
getMail(); //获取当前message
System.out.println("成功获取第" + index + "封邮件");
successCounter++;
} catch (Throwable e) {
errorCounter++;
System.err.println("下载第" + index + "封邮件时出错");
}
}
System.out.println("------------------");
System.out.println("成功下载了" + successCounter + "封邮件");
System.out.println("失败下载了" + errorCounter + "封邮件");
System.out.println("------------------");
}
/**
* 显示邮件的基本信息
*/
private void showMailBasicInfo() throws Exception{
showMailBasicInfo(this.currentMessage);
}
private void showMailBasicInfo(Message message) throws Exception {
System.out.println("-------- 邮件ID：" + this.getMessageId()
+ " ---------");
System.out.println("From：" + this.getFrom());
System.out.println("To：" + this.getTOAddress());
System.out.println("CC：" + this.getCCAddress());
System.out.println("BCC：" + this.getBCCAddress());
System.out.println("Subject：" + this.getSubject());
System.out.println("发送时间：：" + this.getSentDate());
System.out.println("是新邮件？" + this.isNew());
System.out.println("要求回执？" + this.getReplySign());
System.out.println("包含附件？" + this.isContainAttach());
System.out.println("------------------------------");
}
/**
* 获得邮件的收件人，抄送，和密送的地址和姓名，根据所传递的参数的不同
* "to"----收件人 "cc"---抄送人地址 "bcc"---密送人地址
*/
private String getTOAddress() throws Exception {
return getMailAddress("TO", this.currentMessage);
}
private String getCCAddress() throws Exception {
return getMailAddress("CC", this.currentMessage);
}
private String getBCCAddress() throws Exception {
return getMailAddress("BCC", this.currentMessage);
}
/**
* 获得邮件地址
* @param type 类型，如收件人、抄送人、密送人
* @param mimeMessage 邮件消息
* @return
* @throws Exception
*/
private String getMailAddress(String type, Message mimeMessage)
throws Exception {
String mailaddr = "";
String addtype = type.toUpperCase();
InternetAddress[] address = null;
if (addtype.equals("TO") || addtype.equals("CC")
|| addtype.equals("BCC")) {
if (addtype.equals("TO")) {
address = (InternetAddress[]) mimeMessage
.getRecipients(Message.RecipientType.TO);
} else if (addtype.equals("CC")) {
address = (InternetAddress[]) mimeMessage
.getRecipients(Message.RecipientType.CC);
} else {
address = (InternetAddress[]) mimeMessage
.getRecipients(Message.RecipientType.BCC);
}
if (address != null) {
for (int i = 0; i < address.length; i++) {
// 先获取邮件地址
String email = address[i].getAddress();
if (email == null){
email = "";
}else {
email = MimeUtility.decodeText(email);
}
// 再取得个人描述信息
String personal = address[i].getPersonal();
if (personal == null){
personal = "";
} else {
personal = MimeUtility.decodeText(personal);
}
// 将个人描述信息与邮件地址连起来
String compositeto = personal + "<" + email + ">";
// 多个地址时，用逗号分开
mailaddr += "," + compositeto;
}
mailaddr = mailaddr.substring(1);
}
} else {
throw new Exception("错误的地址类型！!");
}
return mailaddr;
}
/**
* 获得发件人的地址和姓名
* @throws Exception
*/
private String getFrom() throws Exception {
return getFrom(this.currentMessage);
}
private String getFrom(Message mimeMessage) throws Exception {
InternetAddress[] address = (InternetAddress[]) mimeMessage.getFrom();
// 获得发件人的邮箱
String from = address[0].getAddress();
if (from == null){
from = "";
}
// 获得发件人的描述信息
String personal = address[0].getPersonal();
if (personal == null){
personal = "";
}
// 拼成发件人完整信息
String fromaddr = personal + "<" + from + ">";
return fromaddr;
}
/**
* 获取messages中message的数量
* @return
*/
private int getMessageCount() {
return this.messages.length;
}
/**
* 获得收件箱中新邮件的数量
* @return
* @throws MessagingException
*/
private int getNewMessageCount() throws MessagingException {
return this.folder.getNewMessageCount();
}
/**
* 获得收件箱中未读邮件的数量
* @return
* @throws MessagingException
*/
private int getUnreadMessageCount() throws MessagingException {
return this.folder.getUnreadMessageCount();
}
/**
* 获得邮件主题
*/
private String getSubject() throws MessagingException {
return getSubject(this.currentMessage);
}
private String getSubject(Message mimeMessage) throws MessagingException {
String subject = "";
try {
// 将邮件主题解码
subject = MimeUtility.decodeText(mimeMessage.getSubject());
if (subject == null){
subject = "";
}
} catch (Exception exce) {
}
return subject;
}
/**
* 获得邮件发送日期
*/
private Date getSentDate() throws Exception {
return getSentDate(this.currentMessage);
}
private Date getSentDate(Message mimeMessage) throws Exception {
return mimeMessage.getSentDate();
}
/**
* 判断此邮件是否需要回执，如果需要回执返回"true",否则返回"false"
*/
private boolean getReplySign() throws MessagingException {
return getReplySign(this.currentMessage);
}
private boolean getReplySign(Message mimeMessage) throws MessagingException {
boolean replysign = false;
String needreply[] = mimeMessage
.getHeader("Disposition-Notification-To");
if (needreply != null) {
replysign = true;
}
return replysign;
}
/**
* 获得此邮件的Message-ID
*/
private String getMessageId() throws MessagingException {
return getMessageId(this.currentMessage);
}
private String getMessageId(Message mimeMessage) throws MessagingException {
return ((MimeMessage) mimeMessage).getMessageID();
}
/**
* 判断此邮件是否已读，如果未读返回返回false,反之返回true
*/
private boolean isNew() throws MessagingException {
return isNew(this.currentMessage);
}
private boolean isNew(Message mimeMessage) throws MessagingException {
boolean isnew = false;
Flags flags = mimeMessage.getFlags();
Flags.Flag[] flag = flags.getSystemFlags();
for (int i = 0; i < flag.length; i++) {
if (flag[i] == Flags.Flag.SEEN) {
isnew = true;
break;
}
}
return isnew;
}
/**
* 判断此邮件是否包含附件
*/
private boolean isContainAttach() throws Exception {
return isContainAttach(this.currentMessage);
}
private boolean isContainAttach(Part part) throws Exception {
boolean attachflag = false;
if (part.isMimeType("multipart/*")) {
// 如果邮件体包含多部分
Multipart mp = (Multipart) part.getContent();
// 遍历每部分
for (int i = 0; i < mp.getCount(); i++) {
// 获得每部分的主体
BodyPart bodyPart = mp.getBodyPart(i);
String disposition = bodyPart.getDisposition();
if ((disposition != null)
&& ((disposition.equals(Part.ATTACHMENT)) || (disposition
.equals(Part.INLINE)))){
attachflag = true;
} else if (bodyPart.isMimeType("multipart/*")) {
attachflag = isContainAttach((Part) bodyPart);
} else {
String contype = bodyPart.getContentType();
if (contype.toLowerCase().indexOf("application") != -1){
attachflag = true;
}
if (contype.toLowerCase().indexOf("name") != -1){
attachflag = true;
}
}
}
} else if (part.isMimeType("message/rfc822")) {
attachflag = isContainAttach((Part) part.getContent());
}
return attachflag;
}
/**
* 获得当前邮件
*/
private void getMail() throws Exception {
try {
this.saveMessageAsFile(currentMessage);
this.parseMessage(currentMessage);
} catch (IOException e) {
throw new IOException("保存邮件出错，检查保存路径");
} catch (MessagingException e) {
throw new MessagingException("邮件转换出错");
} catch (Exception e) {
e.printStackTrace();
throw new Exception("未知错误");
}
}
/**
* 保存邮件源文件
*/
private void saveMessageAsFile(Message message) {
try {
// 将邮件的ID中尖括号中的部分做为邮件的文件名
String oriFileName = getInfoBetweenBrackets(this.getMessageId(message)
.toString());
//设置文件后缀名。若是附件则设法取得其文件后缀名作为将要保存文件的后缀名，
//若是正文部分则用.htm做后缀名
String emlName = oriFileName;
String fileNameWidthExtension = this.receiverInfo.getEmailDir()
+ oriFileName + this.receiverInfo.getEmailFileSuffix();
File storeFile = new File(fileNameWidthExtension);
for (int i = 0; storeFile.exists(); i++) {
emlName = oriFileName + i;
fileNameWidthExtension = this.receiverInfo.getEmailDir()
+ emlName + this.receiverInfo.getEmailFileSuffix();
storeFile = new File(fileNameWidthExtension);
}
this.currentEmailFileName = emlName;
System.out.println("邮件消息的存储路径: " + fileNameWidthExtension);
// 将邮件消息的内容写入ByteArrayOutputStream流中
ByteArrayOutputStream baos = new ByteArrayOutputStream();
message.writeTo(baos);
// 读取邮件消息流中的数据
StringReader in = new StringReader(baos.toString());
// 存储到文件
saveFile(fileNameWidthExtension, in);
} catch (MessagingException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
/*
* 解析邮件
*/
private void parseMessage(Message message) throws IOException,
MessagingException {
Object content = message.getContent();
// 处理多部分邮件
if (content instanceof Multipart) {
handleMultipart((Multipart) content);
} else {
handlePart(message);
}
}
/*
* 解析Multipart
*/
private void handleMultipart(Multipart multipart) throws MessagingException,
IOException {
for (int i = 0, n = multipart.getCount(); i < n; i++) {
handlePart(multipart.getBodyPart(i));
}
}
/*
* 解析指定part,从中提取文件
*/
private void handlePart(Part part) throws MessagingException, IOException {
String disposition = part.getDisposition();
String contentType = part.getContentType();
String fileNameWidthExtension = "";
// 获得邮件的内容输入流
InputStreamReader sbis = new InputStreamReader(part.getInputStream());
// 没有附件的情况
if (disposition == null) {
if ((contentType.length() >= 10)
&& (contentType.toLowerCase().substring(0, 10)
.equals("text/plain"))) {
fileNameWidthExtension = this.receiverInfo.getAttachmentDir()
+ this.currentEmailFileName + ".txt";
} else if ((contentType.length() >= 9) // Check if html
&& (contentType.toLowerCase().substring(0, 9)
.equals("text/html"))) {
fileNameWidthExtension = this.receiverInfo.getAttachmentDir()
+ this.currentEmailFileName + ".html";
} else if ((contentType.length() >= 9) // Check if html
&& (contentType.toLowerCase().substring(0, 9)
.equals("image/gif"))) {
fileNameWidthExtension = this.receiverInfo.getAttachmentDir()
+ this.currentEmailFileName + ".gif";
} else if ((contentType.length() >= 11)
&& contentType.toLowerCase().substring(0, 11).equals(
"multipart/*")) {
// System.out.println("multipart body: " + contentType);
handleMultipart((Multipart) part.getContent());
} else { // Unknown type
// System.out.println("Other body: " + contentType);
fileNameWidthExtension = this.receiverInfo.getAttachmentDir()
+ this.currentEmailFileName + ".txt";
}
// 存储内容文件
System.out.println("保存邮件内容到：" + fileNameWidthExtension);
saveFile(fileNameWidthExtension, sbis);
return;
}
// 各种有附件的情况
String name = "";
if (disposition.equalsIgnoreCase(Part.ATTACHMENT)) {
name = getFileName(part);
// System.out.println("Attachment: " + name + " : "
// + contentType);
fileNameWidthExtension = this.receiverInfo.getAttachmentDir() + name;
} else if (disposition.equalsIgnoreCase(Part.INLINE)) {
name = getFileName(part);
// System.out.println("Inline: " + name + " : "
// + contentType);
fileNameWidthExtension = this.receiverInfo.getAttachmentDir() + name;
} else {
// System.out.println("Other: " + disposition);
}
// 存储各类附件
if (!fileNameWidthExtension.equals("")) {
System.out.println("保存邮件附件到：" + fileNameWidthExtension);
saveFile(fileNameWidthExtension, sbis);
}
}
private String getFileName(Part part) throws MessagingException,
UnsupportedEncodingException {
String fileName = part.getFileName();
fileName = MimeUtility.decodeText(fileName);
String name = fileName;
if (fileName != null) {
int index = fileName.lastIndexOf("/");
if (index != -1) {
name = fileName.substring(index + 1);
}
}
return name;
}
/**
* 保存文件内容
* @param fileName 文件名
* @param input 输入流
* @throws IOException
*/
private void saveFile(String fileName, Reader input) throws IOException {
// 为了放置文件名重名，在重名的文件名后面天上数字
File file = new File(fileName);
// 先取得文件名的后缀
int lastDot = fileName.lastIndexOf(".");
String extension = fileName.substring(lastDot);
fileName = fileName.substring(0, lastDot);
for (int i = 0; file.exists(); i++) {
// 如果文件重名，则添加i
file = new File(fileName + i + extension);
}
// 从输入流中读取数据，写入文件输出流
FileWriter fos = new FileWriter(file);
BufferedWriter bos = new BufferedWriter(fos);
BufferedReader bis = new BufferedReader(input);
int aByte;
while ((aByte = bis.read()) != -1) {
bos.write(aByte);
}
// 关闭流
bos.flush();
bos.close();
bis.close();
}
/**
* 获得尖括号之间的字符
* @param str
* @return
* @throws Exception
*/
private String getInfoBetweenBrackets(String str) throws Exception {
int i, j; //用于标识字符串中的"<"和">"的位置
if (str == null) {
str = "error";
return str;
}
i = str.lastIndexOf("<");
j = str.lastIndexOf(">");
if (i != -1 && j != -1){
str = str.substring(i + 1, j);
}
return str;
}
public static void main(String[] args) throws Exception {
MailReceiverInfo receiverInfo = new MailReceiverInfo();
receiverInfo.setMailServerHost("pop.163.com");
receiverInfo.setMailServerPort("110");
receiverInfo.setValidate(true);
receiverInfo.setUserName("***");
receiverInfo.setPassword("***");
receiverInfo.setAttachmentDir("C:/temp/mail/");
receiverInfo.setEmailDir("C:/temp/mail/");
MailReceiver receiver = new MailReceiver(receiverInfo);
receiver.receiveAllMail();
}
}
</script>