Javamail Api 简明教程

JavaMail API - Deleting Emails

在本章中，我们将看到如何使用 JavaMail API 删除电子邮件。删除邮件涉及使用与邮件关联的标记。不同的状态具有不同的标记，一些由系统定义，一些由用户定义。预定义的标记在内部类 Flags.Flag 中定义，并列在下面：

In this chapter we will see how to delete an email using JavaMail API. Deleting messages involves working with the Flags associated with the messages. There are different flags for different states, some system-defined and some user-defined. The predefined flags are defined in the inner class Flags.Flag and are listed below:

  1. Flags.Flag.ANSWERED

  2. Flags.Flag.DELETED

  3. Flags.Flag.DRAFT

  4. Flags.Flag.FLAGGED

  5. Flags.Flag.RECENT

  6. Flags.Flag.SEEN

  7. Flags.Flag.USER

POP 协议仅支持删除邮件。

POP protocol supports only deleting of the messages.

删除程序中遵循的基本步骤：

Basic steps followed in the delete program 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 in READ_WRITE mode.

  4. Retrieves messages from inbox folder.

  5. Iterate through the messages and type "Y" or "y" if you want to delete the message by invoking the method setFlag(Flags.Flag.DELETED, true) on the Message object.

  6. The messages marked DELETED are not actually deleted, until we call the expunge() method on the Folder object, or close the folder with expunge set to true.

  7. Close the store object.

Create Java Class

创建 Java 类文件 ForwardEmail ，其内容如下：

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

package com.tutorialspoint;

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

import javax.mail.Flags;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.Session;
import javax.mail.Store;

public class DeleteEmail {

   public static void delete(String pop3Host, String storeType, String user,
      String password)
   {
      try
      {
         // get the session object
         Properties properties = new Properties();
         properties.put("mail.store.protocol", "pop3");
         properties.put("mail.pop3s.host", pop3Host);
         properties.put("mail.pop3s.port", "995");
         properties.put("mail.pop3.starttls.enable", "true");
         Session emailSession = Session.getDefaultInstance(properties);
         // emailSession.setDebug(true);

         // create the POP3 store object and connect with the pop server
         Store store = emailSession.getStore("pop3s");

         store.connect(pop3Host, user, password);

         // create the folder object and open it
         Folder emailFolder = store.getFolder("INBOX");
         emailFolder.open(Folder.READ_WRITE);

         BufferedReader reader = new BufferedReader(new InputStreamReader(
            System.in));
         // retrieve the messages from the folder in an array and print it
         Message[] messages = emailFolder.getMessages();
         System.out.println("messages.length---" + messages.length);
         for (int i = 0; i < messages.length; i++) {
            Message message = messages[i];
            System.out.println("---------------------------------");
            System.out.println("Email Number " + (i + 1));
            System.out.println("Subject: " + message.getSubject());
            System.out.println("From: " + message.getFrom()[0]);

            String subject = message.getSubject();
            System.out.print("Do you want to delete this message [y/n] ? ");
            String ans = reader.readLine();
            if ("Y".equals(ans) || "y".equals(ans)) {
	       // set the DELETE flag to true
	       message.setFlag(Flags.Flag.DELETED, true);
	       System.out.println("Marked DELETE for message: " + subject);
            } else if ("n".equals(ans)) {
	       break;
            }
         }
         // expunges the folder to remove messages which are marked deleted
         emailFolder.close(true);
         store.close();

      } catch (NoSuchProviderException e) {
         e.printStackTrace();
      } catch (MessagingException e) {
         e.printStackTrace();
      } catch (IOException io) {
         io.printStackTrace();
      }
   }

   public static void main(String[] args) {

      String host = "pop.gmail.com";// change accordingly
      String mailStoreType = "pop3";
      String username = "abc@gmail.com";// change accordingly
      String password = "*****";// change accordingly

      delete(host, mailStoreType, username, password);

   }

}

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 DeleteEmail.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 DeleteEmail.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: DeleteEmail.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: DeleteEmail

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:

messages.length---1
---------------------------------
Email Number 1
Subject: Testing
From: ABC <abc@gmail.com>
Do you want to delete this message [y/n] ? y
Marked DELETE for message: Testing