转,net实现下载

     现在正用的,起初为了省事,直接用了<a  href="down/test.rar">下载</a>..后来又让加个判断,只有登录用户才能下载,本可以在页面通过<% if(--) { %>--等语句实现..上面觉得不合适,那就改成流下载,搜了下,试了下;.

     原文地址:http://hi.baidu.com/%C8%FC%C4%C9%D0%D0%D0%C7/blog..也不是原文地址,他也转载的--

注意点:

1. 根据传入的地址,要获取文件名,可以用类似

 string saveFileName = "";//客户端保存的文件名
 int intStart = filePathTemp.LastIndexOf("//") + 2;
 saveFileName = filePathTemp.Substring(intStart, filePathTemp.Length - intStart);

2.根据传入的地址,获取文件的物理路径,类似

string filePath = Server.MapPath(filePathTemp);//获取实际路径

3.主要是利用Response,基本过程 设置类型->添加头部->写入 ->关闭

Response.ContentType = "application/x-zip-compressed";
Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(saveFileName));

Response.WriteFile(fileInfo.FullName);//文件流实现

//Response.BinaryWrite(bytes);//字节流实现

// Response.OutputStream.Write(buffer, 0, lengthRead);//分段写入

//Response.TransmitFile(filePathTemp);//TransmitFile写入

Response.End(); //关闭

4.保存文件名,是汉字时容易出现乱码:,用类似

Response.AddHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(saveFileName));
Response.AddHeader( "Content-Disposition", "attachment;  filename=" + HttpUtility.UrlEncode(saveFileName, System.Text.Encoding.UTF8));

5. 疑问:

<1>设置为不弹出保存框,没看到效果

<2>当弹出迅雷下载框时,下载的确是本页面的内容

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;
using Microsoft.Win32;
public partial class downLoad : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    #region
   
    //asp.net中无弹出页面实现下载
    //没能看到效果,,,,,不知道为什么?????
    //<summary>
    /// 下载文件
    /// </summary>
    /// <param name="filename">文件物理地址</param>
    protected void DownloadFile(string filePathTemp)
    {

        string saveFileName = "";
        int intStart = filePathTemp.LastIndexOf("//") + 2;
        saveFileName = filePathTemp.Substring(intStart, filePathTemp.Length - intStart);
        //string filePath = Server.MapPath(filePathTemp);//路径

        System.IO.FileInfo fi = new System.IO.FileInfo(filePathTemp);
        string fileextname = fi.Extension;
        string DEFAULT_CONTENT_TYPE = "application/unknown";
        Microsoft.Win32.RegistryKey regkey, fileextkey;
        string filecontenttype;
        try
        {
            regkey = Registry.ClassesRoot;
            fileextkey = regkey.OpenSubKey(fileextname);
            filecontenttype = fileextkey.GetValue("Content Type", DEFAULT_CONTENT_TYPE).ToString();
        }
        catch
        {
            filecontenttype = DEFAULT_CONTENT_TYPE;
        }

        Response.Clear();
        Response.Charset = "utf-8";
        Response.Buffer = true;
        this.EnableViewState = false;
        Response.ContentEncoding = System.Text.Encoding.UTF8;

        Response.AppendHeader("Content-Disposition", "attachment;filename=" + saveFileName);
        Response.ContentType = filecontenttype;

        Response.WriteFile(filePathTemp);
        Response.Flush();
        Response.Close();

        Response.End();
    }

    protected void download_Click(object sender, EventArgs e)
    {
        //文件的物理地址
        string src = "down//1.jpg";
        this.DownloadFile(src);
    }

    #endregion

    protected void Button1_Click1(object sender, EventArgs e)
    {
        downLoad4("down//1.jpg");
        // downLoad2("down//1.jpg");
        //downLoad2("down//boke.xls");
        // downLoad2("down//project.rar");
        //downLoad3("down//图片横着轮流显示.html");
        //this.DownloadFile("down//图片横着轮流显示.html");
    }

    //TransmitFile实现下载
    protected void downLoad1(string filePathTemp)
    {
        /*
          微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite
          下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。
          代码如下：
         */
        string saveFileName = "";//客户端保存的文件名
        int intStart = filePathTemp.LastIndexOf("//") + 2;
        saveFileName = filePathTemp.Substring(intStart, filePathTemp.Length - intStart);

        Response.ContentType = "application/x-zip-compressed";
        Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(saveFileName));

        string filename = Server.MapPath(filePathTemp);
        Response.TransmitFile(filePathTemp);
    }

    //WriteFile实现下载
    /// <summary>
    /// 基本上可以,但是当弹出迅雷框下载时,下载的是本页面--不知道为什么
    /// </summary>
    /// <param name="filePathTemp"></param>
    protected void downLoad2(string filePathTemp)
    {
        /*
          using System.IO;
         */
        //string fileName ="1.jpg";//客户端保存的文件名
        try
        {
            string saveFileName = "";
            int intStart = filePathTemp.LastIndexOf("//") + 2;
            saveFileName = filePathTemp.Substring(intStart, filePathTemp.Length - intStart);
            string filePath = Server.MapPath(filePathTemp);//获取实际路径
            FileInfo fileInfo = new FileInfo(filePath);
            if (fileInfo.Exists == false)
            {
                Response.Write("<script>alert('文件不存在');</script>");
                return;
            }
            Response.Clear();
            Response.ClearContent();
            Response.ClearHeaders();
            Response.AddHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(saveFileName));
            Response.AddHeader("Content-Length", fileInfo.Length.ToString());
            Response.AddHeader("Content-Transfer-Encoding", "binary");
            Response.ContentType = "application/octet-stream";
            //Response.ContentEncoding = System.Text.Encoding.UTF8; 都可以
            Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");

            Response.WriteFile(fileInfo.FullName);
            Response.Flush();
            Response.End();
        }
        catch (Exception ex)
        {
            System.Console.WriteLine(ex.Message.ToString());
            Response.Write("<script>alert('出现错误');</script>");
            return;
        }
    }

    //流方式下载
    protected void downLoad3(string filePathTemp)
    {
        string saveFileName = "";
        int intStart = filePathTemp.LastIndexOf("//") + 2;
        saveFileName = filePathTemp.Substring(intStart, filePathTemp.Length - intStart);
        string filePath = Server.MapPath(filePathTemp);//路径

        //以字符流的形式下载文件
        FileStream fs = new FileStream(filePath, FileMode.Open);
        byte[] bytes = new byte[(int)fs.Length];
        fs.Read(bytes, 0, bytes.Length);
        fs.Close();
        Response.ContentType = "application/octet-stream";
        //通知浏览器下载文件而不是打开
        Response.AddHeader("Content-Disposition", "attachment;   filename=" + HttpUtility.UrlEncode(saveFileName, System.Text.Encoding.UTF8));

        Response.BinaryWrite(bytes);//流写入
        Response.Flush();
        Response.End();

    }

    //WriteFile分块下载
    protected void downLoad4(string filePathTemp)
    {
        string saveFileName = "";//客户端保存的文件名
        int intStart = filePathTemp.LastIndexOf("//") + 2;
        saveFileName = filePathTemp.Substring(intStart, filePathTemp.Length - intStart);

        string filePath = Server.MapPath(filePathTemp);//路径
        System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);

        if (fileInfo.Exists == true)
        {
            const long ChunkSize = 102400;//100K 每次读取文件，只读取100Ｋ，这样可以缓解服务器的压力
            byte[] buffer = new byte[ChunkSize];

            Response.Clear();
            System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
            long dataLengthToRead = iStream.Length;//获取下载的文件总大小
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(saveFileName));
            while (dataLengthToRead > 0 && Response.IsClientConnected)
            {
                int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小
                Response.OutputStream.Write(buffer, 0, lengthRead);
                Response.Flush();
                dataLengthToRead = dataLengthToRead - lengthRead;
            }
            Response.Close();
        }
    }
}

 

 

 需求的变动??还是考虑太差劲,缺乏经验::

1.先是直接放个链接--后又使用流下载--改为只有会员才可以下载..

2.当判断是否登录时::::::先是新建一个页面(如download.aspx),..当点击下载时跳转到新建的页面,并传递下载文件路径作为参数(download.aspx?file=12.jpg)--在download.aspx页面判断是否登录,没有则不提供下载,否则可以下载-----

 3.当不能下载时提示,没有登录,,然后呢?

　　第一:提供登录框引导用户登录或注册,当注册完成后跳转到登陆或注册前下载页面(如msdn下在)..可以把最后的下载页面作为参数放到session中,在登录成功跳转页面,先判断session中的最后页面值是否为空,不为空则跳转到对应页面,为空则跳转到首页??

 　 第二:(上一条嫌麻烦)只在原页面提示:没有登录.其他不在管  ...问题:提示后仍留在下载页download.aspx页面虽然不能下载--解决:用一个隐藏的iframe...把原来的下载链接download.aspx,的targer指向隐藏的iframe:

<table width="214" height="220" border="0" cellpadding="0" cellspacing="0" bgcolor="#FFFFFF">
                            <tr><td valign ="top">
                            <table>
                            <asp:Repeater ID = "repeaterKejian" Runat="server">
                                <ItemTemplate>
                                    <tr>
                                    <td width="34" align="center" class="k004">
                                    <a target="HideFrame"  href='../commonWeb/DownLoadNow.aspx?file=<%# DataBinder.Eval(Container.DataItem, "NewsID") %>' title="点击下载"><img src="../images/disk.png" width="16" height="16"></a></td>
                                    </tr>
                                </ItemTemplate>    
                            </asp:Repeater>
                            </table>
                            </td></tr>
                        </table>

<iframe style="display:none"  id="HideFrame" name="HideFrame" src=""></iframe>

4.当传递一个下载问价路径时,把路径暴露在了地址栏中,后改为传递id..在下载页面重新查一下下载文件路径,进行下载