Servlet中的文件下載

public void doGet(HttpServletRequest request, HttpServletResponse response)   
                    throws ServletException, IOException {   
    response.setContentType("application/jar");   
       
    ServletContext ctx = getServletContext();   
    InputStream is = ctx.getResourceAsStream("/bookCode.jar");   
       
    int read = 0;   
    byte[] bytes = new byte[1024];   
       
    OutputStream os = response.getOutputStream();   
    while ((read = is.read(bytes)) != -1) {   
        os.write(bytes, 0, read);   
    }   
    os.flush();   
    os.close();   
}