.net中下载文件的实例代码

一、//transmitfile实现下载

protected void button_click(object sender, eventargs e)
    {
        /*
        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：
        */
        response.contenttype = "application/x-zip-compressed";
        response.addheader("content-disposition", "attachment;filename=z.zip");
        string filename = server.mappath("download/z.zip");
        response.transmitfile(filename);
    }

二、//writefile实现下载

protected void button2_click(object sender, eventargs e)
    {
        /*
        using system.io;

        */
        string filename = "asd.txt";//客户端保存的文件名
        string filepath = server.mappath("download/aaa.txt");//路径

        fileinfo fileinfo = new fileinfo(filepath);
        response.clear();
        response.clearcontent();
        response.clearheaders();
        response.addheader("content-disposition", "attachment;filename=" + filename);
        response.addheader("content-length", fileinfo.length.tostring());
        response.addheader("content-transfer-encoding", "binary");
        response.contenttype = "application/octet-stream";
        response.contentencoding = system.text.encoding.getencoding("gb2312");
        response.writefile(fileinfo.fullname);
        response.flush();
        response.end();
    }

三、   //writefile分块下载

protected void button3_click(object sender, eventargs e)
    {
        string filename = "aaa.txt";//客户端保存的文件名
        string filepath = server.mappath("download/aaa.txt");//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(filename));
            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();
        }
    }

四、//流方式下载

protected void button4_click(object sender, eventargs e)
    {
        string filename = "aaa.txt";//客户端保存的文件名
        string filepath = server.mappath("download/aaa.txt");//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(filename, system.text.encoding.utf8));
        response.binarywrite(bytes);
        response.flush();
        response.end();
    }

//----------------------------------------------------------

 

public void downloadfile( system.web.ui.page webform,string filenamewhenuserdownload ,string filebody )
{

　　webform.response.clearheaders();
　　webform.response.clear();
　　webform.response.expires = 0;
　　webform.response.buffer = true;
　　webform.response.addheader("accept-language", "zh-tw");
　　//'文件名称
　　webform.response.addheader("content-disposition", "attachment; filename='"+system.web.httputility.urlencode(filenamewhenuserdownload, system.text.encoding.utf8)+"'");
　　webform.response.contenttype = "application/octet-stream";
　　//'文件内容
　　webform.response.write(filebody);//-----------
    webform.response.end();
}

//上面这段代码是下载一个动态产生的文本文件，若这个文件已经存在于服务器端的实体路径，则可以通过下面的函数：

public void downloadfilebyfilepath( system.web.ui.page webform,string filenamewhenuserdownload ,string filepath )
{
　　webform.response.clearheaders();
　　webform.response.clear();
　　webform.response.expires = 0;
    webform.response.buffer = true;
　　webform.response.addheader("accept-language", "zh-tw");
　　//文件名称
　　webform.response.addheader("content-disposition", "attachment; filename='" + system.web.httputility.urlencode(filenamewhenuserdownload, system.text.encoding.utf8) +"'" );
　　webform.response.contenttype = "application/octet-stream";
　　//文件内容
　　webform.response.write(system.io.file.rea}dallbytes(filepath));//---------
　　webform.response.end();

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