编程高手看看这个代码是讲什么？

espnstarsky · 发表于 2011-2-17 04:06:46| 字数 1,319| - LAN

代码实现：

public class DownServlet extends HttpServlet {

private static final long serialVersionUID = 1332534778678L;

private static final int byte_size = 1024;

protected void service(HttpServletRequest request,

         HttpServletResponse response) throws ServletException, IOException {

   response.setContentLength(byte_size); // 输出到客户端的文件大小

   String fileName = "default.dmh";

   response.setContentType("text/plain");

   response.setCharacterEncoding("utf-8");

   response.setHeader("Content-disposition", "attachment; filename="

            + fileName);                            // 设置文件头

   String url = request.getParameter("url");

   URL fileUrl = new URL(url);

   HttpURLConnection httpCon = (HttpURLConnection) fileUrl

            .openConnection();

//    System.out.println("before range.......... "+httpCon.getResponseCode());

   String sProperty = "bytes=10-" + byte_size;    // -后面表示要取多少数据

   httpCon.setRequestProperty("RANGE", sProperty); // 设置偏移量

   System.out.println("after range.......... "+httpCon.getResponseCode());

   InputStream in = httpCon.getInputStream();

   System.out.println("after InputStream.......... "+httpCon.getResponseCode());

   DataInputStream dis = new DataInputStream(in); // 重新包装输入流

   OutputStream out = response.getOutputStream(); // 从httpUrlConnecction中获得输出流

   byte[] b = new byte[byte_size];             // 读取多少

   dis.read(b);

   out.write(b);

   out.flush();

   out.close(); // 关闭输入输出流

   dis.close();

   in.close();

}

}