apache james 服务器+javamail附件显示和下载问题

Question

我已经用javamail显示出附件名称
请问怎么实现
点击【test.txt】可以下载该附件
网上找的一段代码不知道怎么用请各位帮忙！从附件名连接到这个servlet!DownloadServlet.javapackage MailServlet;import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import javax.activation.*;
import javax.mail.*;
import javax.mail.internet.*;
public class DownloadServlet extends HttpServlet
{
    public void service(HttpServletRequest request, HttpServletResponse response)
        throws IOException, ServletException
    {
    HttpSession session = request.getSession();
    String contentType = request.getParameter("contenttype");       //附件的ContentType
    int count = Integer.parseInt(request.getParameter("count"));    //第几个BodyPart
    Object body = session.getAttribute("body");                     //邮件的MimeMultipart 
    if(body != null)
    {
System.out.println("download Start!");
        try
        {
            MimeMultipart mp        = (MimeMultipart)body;
            int i                   = mp.getCount();
            BodyPart part           = mp.getBodyPart(count);
            contentType             = part.getContentType();
            String fileName         = part.getFileName();
            response.setContentType(contentType);
            response.setHeader("Content-Disposition","attachment; filename=" + fileName);
System.out.println("download Start!" + part.getSize());
                InputStream is          = part.getInputStream();
            ServletOutputStream out = response.getOutputStream();
            BufferedInputStream buf = new BufferedInputStream(is);
            byte[] data             = new byte[2048];
            int readed              = buf.read(data);
            while (readed != -1)
            {
                    out.write(data,0,readed);
                    readed = buf.read(data);
            }
            out.flush();
            out.close();
            buf.close();
System.out.println("download Over !");
        }
        catch (Exception ex)
        {
        System.out.println("error : " + ex);
        }
    }
    }
}