Javamail Api 简明教程
JavaMail API - Forwarding Emails
在本章中，我们将看到如何使用 JavaMail API 转发电子邮件。以下是程序中遵循的基本步骤：
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在属性中获取具有 POP 和 SMPT 服务器详细信息的会话对象。我们需要 POP 详细信息来检索邮件，需要 SMPT 详细信息来发送邮件。
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创建 POP3 存储对象并连接到存储。
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创建 Folder 对象并在邮箱中打开适当的文件夹。
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Retrieve messages.
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遍历邮件并键入“Y”或“y”，如果您想要转发。
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获取邮件的所有信息（收件人、发件人、主题、内容）。
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通过使用组成邮件的部件来构建转发邮件。第一部分将是邮件的文本，第二部分将是要转发的邮件。将两者合并成一个多部分。然后，您可以将多部分添加到正确地址的邮件中并发送它。
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依次关闭 Transport、folder 和 store 对象。
Create Java Class
创建 Java 类文件 ForwardEmail ，其内容如下：
package com.tutorialspoint;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Date;
import java.util.Properties;
import javax.mail.BodyPart;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Store;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
public class ForwardEmail {
public static void main(String[] args) {
Properties properties = new Properties();
properties.put("mail.store.protocol", "pop3");
properties.put("mail.pop3s.host", "pop.gmail.com");
properties.put("mail.pop3s.port", "995");
properties.put("mail.pop3.starttls.enable", "true");
properties.put("mail.smtp.auth", "true");
properties.put("mail.smtp.host", "relay.jangosmtp.net");
properties.put("mail.smtp.port", "25");
Session session = Session.getDefaultInstance(properties);
try {
// session.setDebug(true);
// Get a Store object and connect to the current host
Store store = session.getStore("pop3s");
store.connect("pop.gmail.com", "xyz@gmail.com",
"*****");//change the user and password accordingly
// Create a Folder object and open the folder
Folder folder = store.getFolder("inbox");
folder.open(Folder.READ_ONLY);
BufferedReader reader = new BufferedReader(new InputStreamReader(
System.in));
Message[] messages = folder.getMessages();
if (messages.length != 0) {
for (int i = 0, n = messages.length; i < n; i++) {
Message message = messages[i];
// Get all the information from the message
String from = InternetAddress.toString(message.getFrom());
if (from != null) {
System.out.println("From: " + from);
}
String replyTo = InternetAddress.toString(message
.getReplyTo());
if (replyTo != null) {
System.out.println("Reply-to: " + replyTo);
}
String to = InternetAddress.toString(message
.getRecipients(Message.RecipientType.TO));
if (to != null) {
System.out.println("To: " + to);
}
String subject = message.getSubject();
if (subject != null) {
System.out.println("Subject: " + subject);
}
Date sent = message.getSentDate();
if (sent != null) {
System.out.println("Sent: " + sent);
}
System.out.print("Do you want to reply [y/n] : ");
String ans = reader.readLine();
if ("Y".equals(ans) || "y".equals(ans)) {
Message forward = new MimeMessage(session);
// Fill in header
forward.setRecipients(Message.RecipientType.TO,
InternetAddress.parse(from));
forward.setSubject("Fwd: " + message.getSubject());
forward.setFrom(new InternetAddress(to));
// Create the message part
MimeBodyPart messageBodyPart = new MimeBodyPart();
// Create a multipart message
Multipart multipart = new MimeMultipart();
// set content
messageBodyPart.setContent(message, "message/rfc822");
// Add part to multi part
multipart.addBodyPart(messageBodyPart);
// Associate multi-part with message
forward.setContent(multipart);
forward.saveChanges();
// Send the message by authenticating the SMTP server
// Create a Transport instance and call the sendMessage
Transport t = session.getTransport("smtp");
try {
//connect to the smpt server using transport instance
//change the user and password accordingly
t.connect("abc", "*****");
t.sendMessage(forward, forward.getAllRecipients());
} finally {
t.close();
}
System.out.println("message forwarded successfully....");
// close the store and folder objects
folder.close(false);
store.close();
}// end if
}// end for
}// end if
} catch (Exception e) {
e.printStackTrace();
}
}
}Compile and Run
现在我们的类已经准备好了，让我们编译上述类。我已经将类 ForwardEmail.java 保存到目录： /home/manisha/JavaMailAPIExercise 。我们需要类路径中的 jars javax.mail.jar 和 activation.jar。从命令提示符执行以下命令来编译类（两个 jars 都放在 /home/manisha/ 目录中）：
javac -cp /home/manisha/activation.jar:/home/manisha/javax.mail.jar: ForwardEmail.java现在编译类后，执行以下命令来运行：
java -cp /home/manisha/activation.jar:/home/manisha/javax.mail.jar: ForwardEmail
