java - 为什么调用 OutputStream.flush() 时我的浏览器没有收到数据？

Question

我有一个 servlet，它只读取文件并将其发送到浏览器。文件读取正确，但在 OutputStream.flush() 上，浏览器未收到任何数据。

火狐说:“内容损坏错误 由于检测到数据传输错误，无法显示您尝试查看的页面。”。Firebug 显示状态“已中止”。

IE 打开或保存空文件。我尝试过小文件或大文件。

代码是:

    /** 
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // Use a ServletOutputStream because we may pass binary information
        response.reset();
        OutputStream out = response.getOutputStream();

        // Get the file to view
        String file = request.getParameter("path");

        // Get and set the type and size of the file
        String contentType = getServletContext().getMimeType(file);
        response.setContentType(contentType);
        long fileSize = (new File(file)).length();
        response.setHeader("Content-Length:", "" + fileSize);

        File f = new File(file);
        response.setHeader("Content-Disposition", "attachment;filename="+f.getName()); 
        response.setContentLength((int) fileSize);

        // Return the file
        try {
            returnFile(file, out, response);
        } catch (Exception e) {
            Logger.getLogger(AffichageItemsServlet.class).error("", e);
        } finally {
            out.close();
        }
    }

    // Send the contents of the file to the output stream
    public static void returnFile(String filename, OutputStream out, HttpServletResponse resp)
            throws FileNotFoundException, IOException {
        FileInputStream fis = null;

        try {
            fis = new FileInputStream(filename);
            byte[] buff = new byte[8* 1024];

            int nbRead = 0;
            while ((nbRead = fis.read(buff, 0, buff.length)) !=-1) {
                out.write(buff, 0, nbRead);
            }

            out.flush();
        } finally {
            if (fis != null) {
                fis.close();
            }
        }
    }

响应在“out.flush”上发送。

有什么想法吗？

Answer 1

首先，删除这一行(您在下面调用 setContentLength() ):

response.setHeader("Content-Length:", "" + fileSize);

此外，您可以尝试将 getOutputStream() 调用移至开始使用流之前。