怎样把远程URL下载下来?

Question

怎样把远程URL(如http://zi.csdn.net/58560ali.jpg)自动下载并保存在D:\下呢?

Answer 1

   WebRequest web = WebRequest.Create("http://zi.csdn.net/58560ali.jpg");
        WebResponse wrp = web.GetResponse();
        Stream stream = wrp.GetResponseStream();
        int n = (int)wrp.ContentLength;
        byte[] byteImg = new byte[n];
        stream.Read(byteImg,0,n);
        wrp.Close();
        FileStream fs = File.Create("d:\\1.jpg");
        fs.Write(byteImg, 0, n);
        fs.Close();

Answer 2

//以前做的，仅供参考
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.Threading; 
using System.Data.SqlClient; 
using System.IO; 
using System.Net; public partial class Default2 : System.Web.UI.Page 
{ 
    private WebClient client = new WebClient(); 
    private string URLAddress = string.Empty; 
    private string fileName = string.Empty;     #region 窗体加载事件 
    protected void Page_Load(object sender, EventArgs e) 
    { 
        this.Title = "测试网页"; 
        Securities security = new Securities(); 
        if (!security.HasLogined()) 
        { 
            Response.Write(" <script>alert('请先登陆！') </script>"); 
            Server.Transfer("Default.aspx"); 
        } 
        string role = Session["role"].ToString(); 
        if (!role.Equals("employee")) 
        { 
            Response.Write(" <script>alert('很抱歉,您的权限不够！') </script>"); 
            Server.Transfer("Default.aspx"); 
        } 
        if (!Page.IsPostBack) 
        { 
            DownFileToDirectory(); 
        } 
    } 
    #endregion     #region 将选定的种子文件下载到指定目录下 
    private void DownFileToDirectory() 
    { 
        if (Request["key"] != null && !Request["key"].Equals(string.Empty)) 
        { 
            try 
            { 
                int fid = Convert.ToInt32(Request["key"]);      //文件的编号，从库中取，服务端有此资源 
                string connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; 
                SqlConnection conn = new SqlConnection(connStr); 
                string sql = "select FileName from fileTable where fileId=" + fid + ""; 
                SqlDataAdapter adapter = new SqlDataAdapter(sql, conn); 
                DataTable dt = new DataTable(); 
                adapter.Fill(dt); 
                if (dt.Rows.Count > 0) 
                { 
                    URLAddress = "http://192.168.1.210/Test/DownloadList.aspx"; 
                    fileName = dt.Rows[0]["FileName"].ToString(); 
                    StartDownload(); 
                } 
            } 
            catch 
            { 
                Response.Redirect("Download.aspx"); 
            } 
        } 
        Response.Redirect("Download.aspx"); 
    } 
    #endregion     #region 下载某网页的文件 
    private void DownloadFileByUrl() 
    { 
        string Dir = @"C:\Program Files\myDirectory\fileByDownload"; 
        if (!Directory.Exists(Dir)) 
        { 
            Directory.CreateDirectory(Dir); 
        } 
        string savePath = Dir + "\\" + fileName; 
        if (File.Exists(savePath)) 
        { 
            return; 
        }         try 
        { 
            WebRequest myre = WebRequest.Create(URLAddress); 
        } 
        catch (WebException exp) 
        { 
            string e = exp.Message; 
        }         try 
        { 
            client.Credentials = CredentialCache.DefaultCredentials; 
            client.DownloadFile(URLAddress, savePath); 
        } 
        catch (WebException exp) 
        { 
            string e = exp.Message; 
        } 
        finally 
        { 
            Thread cur = Thread.CurrentThread; 
            if (cur.Name.Equals("autoDown")) 
            { 
                cur.Abort(); 
            } 
        } 
    } 
    #endregion     #region 启用线程,下载文件 
    private void StartDownload() 
    { 
        Thread th = new Thread(new ThreadStart(DownloadFileByUrl)); 
        th.Name = "autoDown"; 
        th.Start(); 
    } 
    #endregion 
}

Answer 3

  /// <summary>
        ///  下载文件
        /// </summary>
        /// <param name="PageUrl">网址</param>
        /// <param name="filename">保存文件路径</param>
        public void DownFile(string PageUrl, string filename)
        {
            if (!Directory.Exists(filename))
            {
                Directory.CreateDirectory(filename);
            }
            string  path = PageUrl.Substring(PageUrl.LastIndexOf("/") + 1);
            string dirname = filename + "\\" + path;
            if (File.Exists(dirname))
            {
                return;
            }
            else
            {
                try
                {                    
                    WebClient wc = new WebClient();
                    WebProxy wp = new WebProxy(al[proxy].ToString(), true);
                    wc.Proxy = wp;
                    wc.DownloadFile(PageUrl, dirname);
                }
                catch (WebException ex)
                {                   
                    if (ex.Status == WebExceptionStatus.ProtocolError)
                    {
                        //文件未找到--跳出 
                        //MessageBox.Show(ex.ToString());
                        return;
                    }
                    else
                    {
                        //换代理 IP
                        //MessageBox.Show(ex.ToString());
                        proxy++;
                        if (proxy >= al.Count)
                        {
                            al = ReadIPproxy("e:\\test.txt");//初始化代理   IP
                        }
                        DownFile(PageUrl, filename);
                    }
                }
            }        }