使用Java程序发送电子邮件


使用Java应用程序发送电子邮件非常简单,但首先你应该在你的机器上安装**JavaMail API**和**Java Activation Framework (JAF)**。

下载并解压这些文件,在新创建的顶级目录中,你会找到这两个应用程序的许多jar文件。你需要将**mail.jar**和**activation.jar**文件添加到你的CLASSPATH中。

发送简单的电子邮件

这是一个从你的机器发送简单电子邮件的例子。假设你的**本地主机**已连接到互联网,并且能够发送电子邮件。

示例

// 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 = "[email protected]";

      // Sender's email ID needs to be mentioned
      String from = "[email protected]";

      // 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();
      }
   }
}

编译并运行此程序以发送简单的电子邮件:

输出

$ java SendEmail
Sent message successfully....

如果你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

以下是参数的说明:

  • **type** - 这将设置为TO,CC或BCC。其中CC代表抄送,BCC代表密送。例如:Message.RecipientType.TO

  • **addresses** - 这是一个电子邮件ID数组。在指定电子邮件ID时,需要使用InternetAddress()方法。

发送HTML电子邮件

这是一个从你的机器发送HTML电子邮件的例子。假设你的**本地主机**已连接到互联网,并且能够发送电子邮件。

此示例与前一个示例非常相似,不同之处在于我们在这里使用setContent()方法来设置内容,其第二个参数是“text/html”,用于指定邮件中包含HTML内容。

使用此示例,你可以发送任意大小的HTML内容。

示例

// 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 = "[email protected]";

      // Sender's email ID needs to be mentioned
      String from = "[email protected]";

      // 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();
      }
   }
}

编译并运行此程序以发送HTML电子邮件:

输出

$ java SendHTMLEmail
Sent message successfully....

发送电子邮件附件

这是一个从你的机器发送包含附件的电子邮件的例子。假设你的**本地主机**已连接到互联网,并且能够发送电子邮件。

示例

// 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 = "[email protected]";

      // Sender's email ID needs to be mentioned
      String from = "[email protected]";

      // 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();
      }
   }
}

编译并运行此程序以发送HTML电子邮件:

输出

$ java SendFileEmail
Sent message successfully....

用户身份验证部分

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

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

其余的电子邮件发送机制将与上面解释的相同。

更新于:2019年7月30日

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