• Java 视频教程

Java - 发送电子邮件

使用 Java 应用程序发送电子邮件非常简单，但首先您应该在计算机上安装JavaMail API和Java 激活框架 (JAF) 。

下载并解压这些文件，在新创建的顶级目录中，您将找到这两个应用程序的许多 jar 文件。您需要在 CLASSPATH 中添加mail.jar和activation.jar文件。

发送一封简单的电子邮件

以下是从您的计算机发送简单电子邮件的示例。假设您的本地主机已连接到 Internet 并且有足够的能力发送电子邮件。

例子

// File Name SendEmail.java

import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

public class SendEmail {

   public static void main(String [] args) {    
      // Recipient's email ID needs to be mentioned.
      String to = "abcd@gmail.com";

      // Sender's email ID needs to be mentioned
      String from = "web@gmail.com";

      // Assuming you are sending email from localhost
      String host = "localhost";

      // Get system properties
      Properties properties = System.getProperties();

      // Setup mail server
      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.
      Session session = Session.getDefaultInstance(properties);

      try {
         // Create a default MimeMessage object.
         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.
         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

         // Set Subject: header field
         message.setSubject("This is the Subject Line!");

         // Now set the actual message
         message.setText("This is actual message");

         // Send message
         Transport.send(message);
         System.out.println("Sent message successfully....");
      } catch (MessagingException mex) {
         mex.printStackTrace();
      }
   }
}

输出

编译并运行该程序以发送简单的电子邮件 -

$ java SendEmail
Sent message successfully....

如果您想向多个收件人发送电子邮件，则可以使用以下方法指定多个电子邮件 ID -

void addRecipients(Message.RecipientType type, Address[] addresses)
   throws MessagingException

这是参数的描述 -

  • type - 这将设置为 TO、CC 或 BCC。这里CC代表抄送，BCC代表黑抄送。示例：Message.RecipientType.TO

  • 地址- 这是电子邮件 ID 的数组。在指定电子邮件 ID 时，您需要使用 InternetAddress() 方法。

发送 HTML 电子邮件

以下是从您的计算机发送 HTML 电子邮件的示例。这里假设您的本地主机已连接到互联网并且有足够的能力发送电子邮件。

此示例与上一个示例非常相似，只不过这里我们使用 setContent() 方法来设置第二个参数为“text/html”的内容，以指定消息中包含 HTML 内容。

使用此示例，您可以发送任意大小的 HTML 内容。

例子

// File Name SendHTMLEmail.java

import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

public class SendHTMLEmail {

   public static void main(String [] args) {
      // Recipient's email ID needs to be mentioned.
      String to = "abcd@gmail.com";

      // Sender's email ID needs to be mentioned
      String from = "web@gmail.com";

      // Assuming you are sending email from localhost
      String host = "localhost";

      // Get system properties
      Properties properties = System.getProperties();

      // Setup mail server
      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.
      Session session = Session.getDefaultInstance(properties);

      try {
         // Create a default MimeMessage object.
         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.
         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

         // Set Subject: header field
         message.setSubject("This is the Subject Line!");

         // Send the actual HTML message, as big as you like
         message.setContent("<h1>This is actual message</h1>", "text/html");

         // Send message
         Transport.send(message);
         System.out.println("Sent message successfully....");
      } catch (MessagingException mex) {
         mex.printStackTrace();
      }
   }
}

编译并运行该程序以发送 HTML 电子邮件 -

输出

$ java SendHTMLEmail
Sent message successfully....

通过电子邮件发送附件

以下是从您的计算机发送带有附件的电子邮件的示例。这里假设您的本地主机已连接到互联网并且有足够的能力发送电子邮件。

例子

// File Name SendFileEmail.java

import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

public class SendFileEmail {

   public static void main(String [] args) {     
      // Recipient's email ID needs to be mentioned.
      String to = "abcd@gmail.com";

      // Sender's email ID needs to be mentioned
      String from = "web@gmail.com";

      // Assuming you are sending email from localhost
      String host = "localhost";

      // Get system properties
      Properties properties = System.getProperties();

      // Setup mail server
      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.
      Session session = Session.getDefaultInstance(properties);

      try {
         // Create a default MimeMessage object.
         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.
         message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));

         // Set Subject: header field
         message.setSubject("This is the Subject Line!");

         // Create the message part 
         BodyPart messageBodyPart = new MimeBodyPart();

         // Fill the 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 = "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 mex) {
         mex.printStackTrace();
      }
   }
}

编译并运行该程序以发送 HTML 电子邮件 -

输出

$ java SendFileEmail
Sent message successfully....

用户认证部分

如果需要向电子邮件服务器提供用户 ID 和密码以进行身份​​验证，则可以按如下方式设置这些属性 -

props.setProperty("mail.user", "myuser");
props.setProperty("mail.password", "mypwd");

电子邮件发送机制的其余部分将保持如上所述。