Java 文件下载

            out = new BufferedOutputStream(response.getOutputStream());

            if (valueMap == null) {
                isSuc = true;
                return;
            }

            if (ret.endsWith("output.xls")) {
                // 文件下载
                response.setContentType("application/octet-stream; CHARSET=GB2312");
                response.setHeader("Content-Disposition", "attachment; filename="
                        + response.encodeURL(new String("数据更新结果.xls".getBytes("gb2312"), "iso8859-1")));

                System.out.println("ret file name" + ret);
                SmartUpload su = new SmartUpload();

                su.initialize(servletConfig, request, response);
                su.setContentDisposition(null);
                su.downloadFile(ret);

                File file = new File(ret);
                byte[] buff = new byte[512];

                in = new BufferedInputStream(new FileInputStream(file));
                while ((in.read(buff) != -1)) {
                    out.write(buff);
                }

                if (file.exists())//删除文件
                    file.delete();
            } else {
                isSuc = true;
            }