身份验证（Authentication）

在前面的“ 检查电子邮件和获取电子邮件”章节中，我们在连接到您的邮箱存储时传递了授权凭据（用户广告密码）和主机。 相反，我们可以将Properties配置为拥有主机，并告诉Session您的自定义Authenticator实例。 这显示在下面的示例中:

创建Java类 (Create Java Class)

我们将从“ 检查电子邮件 ”一章修改我们的CheckingMails.java。 其内容如下:

package cn.xnip;
import java.util.Properties;
import javax.mail.Authenticator;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Store;
public class CheckingMails {
   public static void check(String host, String storeType, String user,
      String password) 
   {
      try {
      // create properties field
      Properties properties = new Properties();
      properties.put("mail.pop3s.host", host);
      properties.put("mail.pop3s.port", "995");
      properties.put("mail.pop3s.starttls.enable", "true");
      // Setup authentication, get session
      Session emailSession = Session.getInstance(properties,
         new javax.mail.Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
               return new PasswordAuthentication(
                  "manisha@gmail.com", "manisha123");
            }
         });
      // emailSession.setDebug(true);
      // create the POP3 store object and connect with the pop server
      Store store = emailSession.getStore("pop3s");
      store.connect();
      // create the folder object and open it
      Folder emailFolder = store.getFolder("INBOX");
      emailFolder.open(Folder.READ_ONLY);
      // 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, n = messages.length; i < n; 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]);
         System.out.println("Text: " + message.getContent().toString());
      }
      // close the store and folder objects
      emailFolder.close(false);
      store.close();
      } catch (NoSuchProviderException e) {
         e.printStackTrace();
      } catch (MessagingException e) {
         e.printStackTrace();
      } catch (Exception e) {
         e.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
      check(host, mailStoreType, username, password);
   }
}

您可以通过取消注释语句emailSession.setDebug(true);来设置调试emailSession.setDebug(true);

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CheckingMails.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: CheckingMails.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: CheckingMails

验证输出 (Verify Output)

您可以在命令控制台上看到类似的消息:

messages.length---3
---------------------------------
Email Number 1
Subject: Today is a nice day
From: XYZ <xyz@gmail.com>
Text: javax.mail.internet.MimeMultipart@45f676cb
---------------------------------
Email Number 2
Subject: hiiii....
From: XYZ <xyz@gmail.com>
Text: javax.mail.internet.MimeMultipart@37f12d4f
---------------------------------
Email Number 3
Subject: helloo
From: XYZ <xyz@gmail.com>
Text: javax.mail.internet.MimeMultipart@3ad5ba3a