Java收邮件功能

在同事帮助下写了一个javaMail收邮件的功能 好像用不成
请哪位大哥赐教下~ 实在没办法了 只要收件功能就行了
[b]问题补充：[/b]
总是报这个异常javax.mail.NoSuchProviderException: Invalid protocol: null
at javax.mail.Session.getProvider(Session.java:431)
at javax.mail.Session.getStore(Session.java:530)

代码
package com.abank.util;

import com.ReciveOneMail;

import javax.mail.*;
import javax.mail.internet.MimeMessage;
import java.util.Properties;

/**

• Created by IntelliJ IDEA.
• User: Administrator
• Date: 2009-11-27
• Time: 16:17:13

• To change this template use File | Settings | File Templates.
  */
  public class MainSender {
  // 接受邮件
  // 接受邮件
  public static String getMail() throws Exception{
  String host = "pop3.163.com";

  // 创建Properties 对象
  Properties props = new Properties();
  final String username = "shaersashajindan@163.com";
  final String password = "327521526";
  // 创建邮件会话
  Session session = Session.getDefaultInstance(props,null);
  try {
      // 获取邮箱的pop3存储
       URLName urln = new URLName("pop3");
      Store store = session.getStore(urln);
      store.connect(host, username, password);
  
      // 获取inbox文件
      Folder folder = store.getFolder("INBOX");
      folder.open(Folder.READ_ONLY); // 打开，打开后才能读取邮件信息
  
      // 获取邮件消息
      Message[] message = folder.getMessages();
  
      FetchProfile profile = new FetchProfile();
      profile.add(FetchProfile.Item.ENVELOPE);
      folder.fetch(message, profile);
  
      System.out.println("unread message count =:"+folder.getDeletedMessageCount());
      System.out.println("message length =:"+message.length);
      System.out.println("Messages's length: " + message.length);
      ReciveOneMail pmm = null;
      for (int i = 0, n = message.length; i < n; i++) {
          System.out.println("============================================================");
          pmm = new ReciveOneMail((MimeMessage) message[i]);
          System.out.println("Message " + i + " subject: "
                  + pmm.getSubject());
          System.out.println("Message " + i + " sentdate: "
                  + pmm.getSentDate());
          System.out.println("Message " + i + " replysign: "
                  + pmm.getReplySign());
          System.out.println("Message " + i + " hasRead: " + pmm.isNew());
          System.out.println("Message " + i + "  containAttachment: "
                  + pmm.isContainAttach((Part) message[i]));
          System.out.println("Message " + i + " form: " + pmm.getFrom());
          System.out.println("Message " + i + " to: "
                  + pmm.getMailAddress("to"));
          System.out.println("Message " + i + " cc: "
                  + pmm.getMailAddress("cc"));
          System.out.println("Message " + i + " bcc: "
                  + pmm.getMailAddress("bcc"));
          pmm.setDateFormat("yy年MM月dd日 HH:mm");
          System.out.println("Message " + i + " sentdate: "
                  + pmm.getSentDate());
          System.out.println("Message " + i + " Message-ID: "
                  + pmm.getMessageId());
          // 获得邮件内容===============
          pmm.getMailContent((Part) message[i]);
          System.out.println("Message " + i + " bodycontent: \r\n"
                  + pmm.getBodyText());
          pmm.setAttachPath("c:\\mailfile");
          pmm.saveAttachMent((Part) message[i]);
          message[i].setFlag(Flags.Flag.DELETED, true);
          if(message[i].isSet(Flags.Flag.DELETED))
              System.out.println("邮件已删除");
  
      }
  
      // 关闭资源
      folder.close(true);
      store.close();
      System.out.println("success");
  } catch (MessagingException e) {
      e.printStackTrace();
  }
  
  System.out.println("GetMail Process Over!");
  return "ririri";
  

  }
  }

参考实例文章

http://www.iteye.com/topic/49031

http://xiangzhengyan.iteye.com/blog/85961