byte[] buffer = new byte[1024 * 1024 * 5];
            using (MemoryStream st = new MemoryStream())//MemoryStream为内存流
            {
                //ZipOutputStream类的构造函数需要一个流，文件流、内存流都可以，压缩后的内容会写入到这个流中。
                using (ZipOutputStream zipStream = new ZipOutputStream(st))
                {
                    string str = CommonHelper.HttpGetFile(uri);//此处为下载的文件转换成了字符串
                    if (!string.IsNullOrEmpty(str))
                    {
                        byte[] bytes = Encoding.UTF8.GetBytes(str);
                        ZipEntry zipEntry = new ZipEntry("xxx.doc");
                        zipEntry.DateTime = DateTime.Now;
                        zipEntry.IsUnicodeText = true;
                        zipStream.PutNextEntry(zipEntry);
                        zipStream.Write(bytes,0,bytes.Length);
                        zipStream.CloseEntry();
                    }
                    //获取excel字节并添加到压缩文件
                    buffer = ExcelHelper<T>.OutputExcel();//此处为获取的的excel字节
                    ZipEntry zipEntry2 = new ZipEntry("xxxx.xls");
                    zipEntry2.DateTime = DateTime.Now;
                    zipEntry2.IsUnicodeText = true;//解决文件名乱码
                    zipStream.PutNextEntry(zipEntry2);
                    zipStream.Write(buffer,buffer.Length);
                    zipStream.CloseEntry();
                    //使用流操作时一定要设置IsStreamOwner为false。否则很容易发生在文件流关闭后的异常。
                    zipStream.IsStreamOwner = false;
                    zipStream.Finish();
                    zipStream.Close();
                }
                buffer = st.GetBuffer();
                st.Close();
            }