java文件下载

一、页面上用 超链接 a  或者 是 iframe的src属性

二、Java代码

1、HttpServletResponse 和 HttpServletRequest    2、下面的方法是struts2利用ServletActionContext获取  HttpServletResponse 和 HttpServletRequest    ，spring mvc直接写在方法参数列表即可。 3、IO流读写

    /**

     * 下载订单模板

     * @param response

     * @param req

     * @return

     */

    public String downloadOrderTemplate(){

     

     HttpServletResponse response = ServletActionContext.getResponse();

     HttpServletRequest  req  = ServletActionContext.getRequest();

     

     String fileName = "订单模板.xls";

     String realPath = req.getSession().getServletContext().getRealPath("/guest/distPlatform/excelOrderTemplate/");

     

     System.out.println(realPath);

  System.out.println(new File(realPath,fileName).toString());

     

  BufferedInputStream in;

   

  try {

   

   in = new BufferedInputStream(new FileInputStream(new File(realPath,fileName)));

 

   ByteArrayOutputStream out = new ByteArrayOutputStream();

   byte[] temp = new byte[1024];

   int size = 0;

   while ((size = in.read(temp)) != -1) {

    out.write(temp, 0, size);

   }

   System.out.println(size);

   in.close();

   

   byte[] buff=out.toByteArray();

   

   response.reset();

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

     + new String(fileName.getBytes("gb18030"), "iso8859-1")

     + "\"");

     

   response.addHeader("Content-Length", "" + buff.length);

   response.setContentType("application/octet-stream;charset=UTF-8");

   

   OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());

   outputStream.write(buff);

   outputStream.flush();

   outputStream.close();

  } catch (Exception e) {

            log.info("下载订单模板异常");

   e.printStackTrace();

  }

   

     return null;

    }