Java 简明教程

Java - Sending Email

使用 Java 应用程序发送电子邮件非常简单，但首先应在计算机上安装 JavaMail API 和 Java Activation Framework (JAF)。

To send an e-mail using your Java Application is simple enough but to start with you should have JavaMail API and Java Activation Framework (JAF) installed on your machine.

You can download latest version of JavaMail (Version 1.2) from Java’s standard website.
You can download latest version of JAF (Version 1.1.1) from Java’s standard website.

下载并解压缩这些文件，在新建的顶层目录中，你可以找到这两个应用程序的多个 jar 文件。你需要在你的 CLASSPATH 中添加 mail.jar 和 activation.jar 文件。

Download and unzip these files, in the newly created top level directories you will find a number of jar files for both the applications. You need to add mail.jar and activation.jar files in your CLASSPATH.

Send a Simple E-mail

这里是一个用来从你的机器发送一封简单邮件的示例。假定你的 localhost 已连接至互联网且有能力发送电子邮件。

Here is an example to send a simple e-mail from your machine. It is assumed that your localhost is connected to the Internet and capable enough to send an e-mail.

Example

// 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();
      }
   }
}

Output

编译并运行此程序来发送一封简单电子邮件 −

Compile and run this program to send a simple e-mail −

$ java SendEmail
Sent message successfully....

如果你想发送电子邮件给多个收件人，那么可以使用以下的方法来指定多个电子邮件 ID −

If you want to send an e-mail to multiple recipients then the following methods would be used to specify multiple e-mail IDs −

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

以下是参数说明 −

Here is the description of the parameters −

type − This would be set to TO, CC or BCC. Here CC represents Carbon Copy and BCC represents Black Carbon Copy. Example: Message.RecipientType.TO
addresses − This is an array of e-mail ID. You would need to use InternetAddress() method while specifying email IDs.

Send an HTML E-mail

这里是一个用来从你的机器发送 HTML 电子邮件的示例。此示例假定你的 localhost 已连接到互联网并且能够发送电子邮件。

Here is an example to send an HTML e-mail from your machine. Here it is assumed that your localhost is connected to the Internet and capable enough to send an e-mail.

这个示例与之前的示例非常相似，不同之处在于，这里我们使用 setContent() 方法来设置内容，其第二个参数是“text/html”，指定该消息中包含 HTML 内容。

This example is very similar to the previous one, except here we are using setContent() method to set content whose second argument is "text/html" to specify that the HTML content is included in the message.

使用这个示例，你可以发送任意长度的 HTML 内容。

Using this example, you can send as big as HTML content you like.

Example

// 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();
      }
   }
}

编译并运行此程序来发送一封 HTML 电子邮件 −

Compile and run this program to send an HTML e-mail −

Output

$ java SendHTMLEmail
Sent message successfully....

Send Attachment in E-mail

这里是一个用来从你的机器发送带有附件的电子邮件的示例。此示例假定你的 localhost 已连接到互联网且有能力发送电子邮件。

Here is an example to send an e-mail with attachment from your machine. Here it is assumed that your localhost is connected to the internet and capable enough to send an e-mail.

Example

// 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();
      }
   }
}

编译并运行此程序来发送一封 HTML 电子邮件 −

Compile and run this program to send an HTML e-mail −

Output

$ java SendFileEmail
Sent message successfully....

User Authentication Part

如果需要为电子邮件服务器提供用户 ID 和密码用于认证目的，那么你可以按以下方式设置这些属性 −

If it is required to provide user ID and Password to the e-mail server for authentication purpose, then you can set these properties as follows −

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

发送电子邮件的其余机制保持如上文所述。

Rest of the e-mail sending mechanism would remain as explained above.