步骤

1）先引用 ICSharpCode.SharpZipLib.dll；

2）.cs文件引入

using System.IO;
using System.Text;

using ICSharpCode.SharpZipLib.Checksums;
using ICSharpCode.SharpZipLib.Zip;
using ICSharpCode.SharpZipLib.GZip;

3）代码

 #region 下列代码为压缩并下载代码
       ZipOutputStream zos = null;
       String strBaseDir = "";

       void dlZipDir(string strPath, string strFileName)
       {
           MemoryStream ms = null;
           Response.ContentType = "application/octet-stream";
           strFileName = HttpUtility.UrlEncode(strFileName).Replace('+', ' ');
           Response.AddHeader("Content-Disposition", "attachment;   filename=" + strFileName + ".zip");
           ms = new MemoryStream();
           zos = new ZipOutputStream(ms);
           strBaseDir = strPath + "\\";
           addZipEntry(strBaseDir);
           zos.Finish();
           zos.Close();
           Response.Clear();
           Response.BinaryWrite(ms.ToArray());
           Response.End();
       }

       void addZipEntry(string PathStr)
       {
           DirectoryInfo di = new DirectoryInfo(PathStr);
           foreach (DirectoryInfo item in di.GetDirectories())
           {
               addZipEntry(item.FullName);
           }
           foreach (FileInfo item in di.GetFiles())
           {
               FileStream fs = File.OpenRead(item.FullName);
               byte[] buffer = new byte[fs.Length];
               fs.Read(buffer, 0, buffer.Length);
               string strEntryName = item.FullName.Replace(strBaseDir, "");
               ZipEntry entry = new ZipEntry(strEntryName);
               zos.PutNextEntry(entry);
               zos.Write(buffer, 0, buffer.Length);
               fs.Close();
           }
       }  
      

       PRotected void Button2_Click(object sender, EventArgs e)
        {
            string userPath ="D:\\华海实训（hohisoft.com）各级账号和密码";
        
               dlZipDir(userPath, "华海实训（hohisoft.com）服务账号");

        }

       #endregion