使用javamail API阅读邮件时的阿拉伯语内容问题

我正在使用 Javamail API从Gmail服务器读取邮件.我发送的邮件中包含从gmail ID到其他Gmail ID的阿拉伯语内容.邮件的Charset编码类型是windows-1256.当我使用Javamail下载邮件时,我收到“??????”的内容格式而不是阿拉伯字符.我将下载的内容转换为UTF-8格式,但仍未获得正确的显示.

提前致谢,

蒂姆

更新：
我使用以下代码来获取内容：

Object content = message.getContent(); 
if (message.isMimeType("text/html")  
      || message.isMimeType("text/plain")) { 
      Al = (String) content; 
}

下载内容后,以下代码用于UTF-8编码：

byte[] utf8Bytes = s.getBytes("UTF-8"); 
s = new String(utf8Bytes,"UTF-8");

更新：我目前用于阅读邮件内容的完整代码

String gmailMultipartMailDownload(Multipart multipart,String Uids)
        throws SocketException,UnsupportedDataTypeException,UnsupportedEncodingException {
    String Content = new String("");        
    try {
        int numParts = multipart.getCount();            
        for (int k = 0; k < numParts; k++)
        {
            BodyPart bodyPart = multipart.getBodyPart(k);
            Object tmp = null;
            try 
            {
                tmp = bodyPart.getContent();
            } 
            catch (UnsupportedDataTypeException UEE)
            {
                try {
                    InputStream is = bodyPart.getInputStream();
                    BufferedReader br = new BufferedReader(new InputStreamReader(is));
                    StringBuilder sb = new StringBuilder();
                    String line = null;

                    while ((line = br.readLine()) != null)
                    {
                        sb.append(line + "n");
                    }

                    br.close();
                    return sb.toString();
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (MessagingException e) {                        
                    e.printStackTrace();
                }
            } catch (UnsupportedEncodingException UEE) {
                UEE.printStackTrace();
                try {
                    InputStream is = bodyPart.getInputStream();
                    BufferedReader br = new BufferedReader(new InputStreamReader(is));
                    StringBuilder sb = new StringBuilder();
                    String line = null;

                    while ((line = br.readLine()) != null)
                    {
                        sb.append(line + "n");
                    }

                    br.close();
                    return sb.toString();
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (MessagingException e) {                    
                    e.printStackTrace();
                }
            }   

            String disposition = bodyPart.getDisposition();

            if (tmp instanceof InputStream) {                   
                try{
                    if( super.Downloadfiles(bodyPart,hashCode,attnumcount,this.getgmailattachmentfolder()))
                    {                       
                        //Download Attachments
                    }
                }catch (FileNotFoundException err) {                     
                    return Content;
                }
                catch(IOException fex){                  
                    fex.printStackTrace();
                    return Content;
                }
            }
            else if (disposition != null
                    && (disposition.equals(BodyPart.ATTACHMENT) || disposition.equals(BodyPart.INLINE) || disposition.equals("ATTACHMENT"))) {

                 try{
                     if( super.Downloadfiles(bodyPart,this.getgmailattachmentfolder()))
                {

                        //Download Attachments
                }
                 }catch (FileNotFoundException err) {

                 System.out.println(err.getMessage());
                 return Content;
                 }
                 catch(IOException fex){         

                 fex.printStackTrace();
                 return Content;}
            } else if (bodyPart.isMimeType("multipart/*")) {
                Multipart mp = (Multipart) bodyPart.getContent();               

                Content += gmailMultipartMailDownload(mp,Uids);

            } else if (bodyPart.isMimeType("text/html")) {                  

                Content += bodyPart.getContent().toString();                    
            }
        }
    }

    catch (Exception Ex) {      
        System.out.println("Content object  error is  "+Ex);            
        return Content;         
    } finally {
        return Content;
    }
}

public boolean sendEmail(String sender,String recipient,String subject,String body)
    {
        try
        {
            // set properties of mail server
            Security.addProvider(new com.sun.net.ssl.internal.ssl.Provider());

            Properties props = new Properties();
            props.setProperty("mail.transport.protocol","smtp");
            props.setProperty("mail.host","smtp.gmail.com");
            props.put("mail.smtp.auth","true");
            props.put("mail.smtp.port","465");
            props.setProperty("charset","utf-8");
            props.put("mail.smtp.socketFactory.port","465");
            props.put("mail.smtp.socketFactory.class","javax.net.ssl.SSLSocketFactory");
            props.put("mail.smtp.socketFactory.fallback","false");
            props.setProperty("mail.smtp.quitwait","false");

            // connect to mail server
            javax.mail.Session session = javax.mail.Session.getDefaultInstance(props,new javax.mail.Authenticator()
            {
                protected PasswordAuthentication getPasswordAuthentication()
                { return new PasswordAuthentication(gmailUser,gmailPassword);   }  
            });

            // create email
            MimeMessage message = new MimeMessage(session);
            message.setSender(new InternetAddress(sender));
            message.setSubject(subject,"UTF-8");
            message.setContent(body,"text/plain; charset=utf-8");
            message.setRecipient(Message.RecipientType.TO,new InternetAddress(recipient));

            // send email
            Transport.send(message);

            return true;
       }
       catch (Exception e)
       {
          System.out.println("Exception thown "+e.getMessage());
          return false;
       }