No provider for pop3

import java.io.UnsupportedEncodingException;

import java.security.*;

import java.util.Properties;

import javax.mail.*;

import javax.mail.internet.InternetAddress;

import javax.mail.internet.MimeUtility;



/**

 * 用于收取Gmail邮件

 * @author Winter Lau

 */

public class MailFetch

{

	public static void main(String argv[]) throws Exception 

	{

		Security.addProvider(new com.sun.net.ssl.internal.ssl.Provider());

		final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";

		

		// Get a Properties object

		Properties props = System.getProperties();

		props.setProperty("mail.pop3.socketFactory.class", SSL_FACTORY);

		props.setProperty("mail.pop3.socketFactory.fallback", "false");

		props.setProperty("mail.pop3.port", "995");

		props.setProperty("mail.pop3.socketFactory.port", "995");

		props.put("mail.pop3.host", "pop.gmail.com");   

		//以下步骤跟一般的JavaMail操作相同

		Session session = Session.getDefaultInstance(props,null);

		

		//请将红色部分对应替换成你的邮箱帐号和密码

		URLName urln = new URLName("pop3","pop.gmail.com",995,null,

		"账号", "密码");

		Store store = session.getStore(urln);////////、、//运行在该行时报错

		Folder inbox = null;

		try 

		{

			store.connect();

			inbox = store.getFolder("INBOX");

			inbox.open(Folder.READ_ONLY);

			FetchProfile profile = new FetchProfile();

			profile.add(FetchProfile.Item.ENVELOPE);

			Message[] messages = inbox.getMessages();

			inbox.fetch(messages, profile);

			System.out.println("收件箱的邮件数：" + messages.length);

			for (int i = 0; i < messages.length; i++) 

			{

				//邮件发送者

				String from = decodeText(messages[i].getFrom()[0].toString());

				InternetAddress ia = new InternetAddress(from);

				System.out.println("FROM:" + ia.getPersonal()+'('+ia.getAddress()+')');

				//邮件标题

				System.out.println("TITLE:" + messages[i].getSubject());

				//邮件大小

				System.out.println("SIZE:" + messages[i].getSize());

				//邮件发送时间

				System.out.println("DATE:" + messages[i].getSentDate());

			}

		} 

		finally 

		{

			try 

			{

				inbox.close(false);

			} 

			catch (Exception e) 

			{

				

			}

			try 

			{

				store.close();

			} 

			catch (Exception e) 

			{

				

			}

		}

	}

	

	protected static String decodeText(String text) throws UnsupportedEncodingException 

	{

		if (text == null)

		return null;

		if (text.startsWith("=?GB") || text.startsWith("=?gb"))

		text = MimeUtility.decodeText(text);

		else

		text = new String(text.getBytes("ISO8859_1"));

		return text;

	}

}