在电子邮件中发送附件（Send attachment in email）

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2023-12-01

以下是从您的计算机发送包含附件的电子邮件的示例。本地机器上的文件是file.txt放在/home/manisha/ 。在这里，我们使用了JangoSMPT服务器，通过该服务器将电子邮件发送到我们的目标电子邮件地址。环境设置章节中介绍了该设置。

要发送包含内嵌图像的电子邮件，请执行以下步骤:

参加一个会议
创建一个默认的MimeMessage对象，并在消息中设置From, To, Subject 。

设置实际消息如下:

messageBodyPart.setText("This is message body");

创建一个MimeMultipart对象。将上面带有实际消息的messageBodyPart添加到此multipart对象中。

接下来通过创建Datahandler添加附件，如下所示:

messageBodyPart = new MimeBodyPart();
String filename = "/home/manisha/file.txt";
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
multipart.addBodyPart(messageBodyPart);

接下来在消息中设置multipart，如下所示:
```
message.setContent(multipart);
```
使用Transport对象发送消息。

创建Java类 (Create Java Class)

创建一个java类文件SendAttachmentInEmail ，其内容如下:

package cn.xnip;
import java.util.Properties;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.BodyPart;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
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 SendAttachmentInEmail {
   public static void main(String[] args) {
      // Recipient's email ID needs to be mentioned.
      String to = "destinationemail@gmail.com";
      // Sender's email ID needs to be mentioned
      String from = "fromemail@gmail.com";
      final String username = "manishaspatil";//change accordingly
      final String password = "******";//change accordingly
      // Assuming you are sending email through relay.jangosmtp.net
      String host = "relay.jangosmtp.net";
      Properties props = new Properties();
      props.put("mail.smtp.auth", "true");
      props.put("mail.smtp.starttls.enable", "true");
      props.put("mail.smtp.host", host);
      props.put("mail.smtp.port", "25");
      // Get the Session object.
      Session session = Session.getInstance(props,
         new javax.mail.Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
               return new PasswordAuthentication(username, password);
            }
         });
      try {
         // Create a default MimeMessage object.
         Message message = new MimeMessage(session);
         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));
         // Set To: header field of the header.
         message.setRecipients(Message.RecipientType.TO,
            InternetAddress.parse(to));
         // Set Subject: header field
         message.setSubject("Testing Subject");
         // Create the message part
         BodyPart messageBodyPart = new MimeBodyPart();
         // Now set the actual message
         messageBodyPart.setText("This is message body");
         // Create a multipar message
         Multipart multipart = new MimeMultipart();
         // Set text message part
         multipart.addBodyPart(messageBodyPart);
         // Part two is attachment
         messageBodyPart = new MimeBodyPart();
         String filename = "/home/manisha/file.txt";
         DataSource source = new FileDataSource(filename);
         messageBodyPart.setDataHandler(new DataHandler(source));
         messageBodyPart.setFileName(filename);
         multipart.addBodyPart(messageBodyPart);
         // Send the complete message parts
         message.setContent(multipart);
         // Send message
         Transport.send(message);
         System.out.println("Sent message successfully....");
      } catch (MessagingException e) {
         throw new RuntimeException(e);
      }
   }
}

由于我们使用主机提供商JangoSMTP提供的SMTP服务器，我们需要验证用户名和密码。 javax.mail.PasswordAuthentication类用于验证密码。

编译和运行 (Compile and Run)

现在我们的课已经准备好了，让我们编译上面的类。我已将类SendAttachmentInEmail.java保存到目录: /home/manisha/JavaMailAPIExercise 。我们需要在类路径中使用jars javax.mail.jar和activation.jar 。执行以下命令从命令提示符编译类（两个jar放在/ home/manisha /目录中）:

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

现在编译了类，执行以下命令来运行:

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

验证输出 (Verify Output)

您应该在命令控制台上看到以下消息:

Sent message successfully....

当我通过JangoSMTP向我的Gmail地址发送电子邮件时，我的gmail帐户收件箱中会收到以下邮件: