Javamail Api 简明教程

JavaMail API - Replying Emails

在本章中，我们将学习如何使用 JavaMail API 回复电子邮件。下面程序中遵循的基本步骤：

In this chapter we will see how to reply to an email using JavaMail API. Basic steps followed in the program below are:

  1. Get the Session object with POP and SMPT server details in the properties. We would need POP details to retrieve messages and SMPT details to send messages.

  2. Create POP3 store object and connect to the store.

  3. Create Folder object and open the appropriate folder in your mailbox.

  4. Retrieve messages.

  5. Iterate through the messages and type "Y" or "y" if you want to reply.

  6. Get all information (To,From,Subject, Content) of the message.

  7. Build the reply message, using Message.reply() method. This method configures a new Message with the proper recipient and subject. The method takes a boolean parameter indicating whether to reply to only the sender (false) or reply to all (true).

  8. Set From,Text and Reply-to in the message and send it through the instance of Transport object.

  9. Close the Transport, folder and store objects respectively.

Create Java Class

创建 java 类文件 ReplyToEmail ，其内容如下：

Create a java class file ReplyToEmail, the contents of which are as follows:

package com.tutorialspoint;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Date;
import java.util.Properties;

import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Store;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class ReplyToEmail {
   public static void main(String args[])
   {
      Date date = null;

      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.starttls.enable", "true");
      properties.put("mail.smtp.host", "relay.jangosmtp.net");
      properties.put("mail.smtp.port", "25");
      Session session = Session.getDefaultInstance(properties);

      // session.setDebug(true);
      try
      {
         // 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

         Folder folder = store.getFolder("inbox");
         if (!folder.exists()) {
            System.out.println("inbox not found");
               System.exit(0);
         }
         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];
               date = message.getSentDate();
               // 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 replyMessage = new MimeMessage(session);
                  replyMessage = (MimeMessage) message.reply(false);
                  replyMessage.setFrom(new InternetAddress(to));
                  replyMessage.setText("Thanks");
                  replyMessage.setReplyTo(message.getReplyTo());

                  // 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(replyMessage,
                        replyMessage.getAllRecipients());
                  } finally {
                     t.close();
                  }
                  System.out.println("message replied successfully ....");

                  // close the store and folder objects
                  folder.close(false);
                  store.close();

               } else if ("n".equals(ans)) {
                  break;
               }
            }//end of for loop

         } else {
            System.out.println("There is no msg....");
         }

      } 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 ReplyToEmail.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）：

Now that our class is ready, let us compile the above class. I’ve saved the class ReplyToEmail.java to directory : /home/manisha/JavaMailAPIExercise. We would need the jars javax.mail.jar and activation.jar in the classpath. Execute the command below to compile the class (both the jars are placed in /home/manisha/ directory) from command prompt:

javac -cp /home/manisha/activation.jar:/home/manisha/javax.mail.jar: ReplyToEmail.java

现在编译类后，执行以下命令来运行：

Now that the class is compiled, execute the following command to run:

java -cp /home/manisha/activation.jar:/home/manisha/javax.mail.jar: ReplyToEmail

Verify Output

您应该在命令控制台上看到以下消息：

You should see the following message on the command console:

From: ABC <abc@gmail.com>
Reply-to: abc@trioteksolutions.com
To: XYZ <xyz@gmail.com>
Subject: Hi today is a nice day
Sent: Thu Oct 17 15:58:37 IST 2013
Do you want to reply [y/n] : y
message replied successfully ....

查看邮件已发送到的收件箱。在我们的案例中，接收到的消息如下所示：

Check the inbox to which the mail was sent. In our case the message received looks as below:

replymessage