一、文件流方式获取网络图片资源
方法1
string url = string.Format(@"http://webservice.36wu.com/DimensionalCodeService.asmx/GetCodeImgByString?size={0}&content={1}", 5, 123456); System.Net.WebRequest webreq = System.Net.WebRequest.Create(url); System.Net.WebResponse webres = webreq.GetResponse(); using(System.IO.Stream stream = webres.GetResponseStream()) { ictureBox1.Image = Image.FromStream(stream); }
方法2
生成图片的URL假设是这样：http://localhost/administrator/qrcode.aspx?pid=78
qrcode.aspx.cs的生成图片的部分代码：
Image image = new Bitmap(200, 200); Graphics g = Graphics.FromImage(image); try { string url="http://localhost"; DotNetBarcode bc = new DotNetBarcode(); bc.Type = DotNetBarcode.Types.QRCode; bc.PrintCheckDigitChar = true; bc.WriteBar(url, 0, 0, 210, 210, g); System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Png); Response.ClearContent(); //Response.ContentType = "image/Png"; //Response.BinaryWrite(ms.ToArray());
Response.ContentType = "application/octet-stream"; Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode("qrcode.png", System.Text.Encoding.UTF8)); Response.BinaryWrite(ms.ToArray());
ms.Dispose(); } finally { g.Dispose(); image.Dispose(); }
或者这样
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();
二、WebClient方式从服务器上下载文件
参考方法1：
/// <summary> /// 下载服务器文件至客户端 /// </summary> /// <param name="url">被下载的文件地址，绝对路径</param> /// <param name="dir">另存放的目录</param> public void DownloadUrlFile(string url, string dir) { WebClient client = new WebClient(); string fileName = Path.GetFileName(url); //被下载的文件名 string path = dir + fileName; //另存为的绝对路径＋文件名 try { if (!System.IO.Directory.Exists(dir)) { System.IO.Directory.CreateDirectory(dir); } if (!System.IO.File.Exists(path)) { client.DownloadFile(url, path); } } catch (Exception) { // ShowError("文件下载失败！"); } }
参考方法2 [2]
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="GetPictureByUrl.aspx.cs" Inherits="HoverTreeMobile.GetPictureByUrl" %> <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <meta name="viewport" content="width=device-width, initial-scale=1" /> <title>根据网址把图片下载到服务器 - 何问起</title> </head> <body> <form id="form1" runat="server"> <div> 图片网址：<br /><asp:TextBox runat="server" ID="textBoxImgUrl" Width="500" Text="http://hovertree.com/hvtimg/201508/cnvkv745.jpg" /> <br /> <asp:Button runat="server" ID="btnImg" Text="下载" OnClick="btnImg_Click" /> <br /><asp:Image runat="server" ID="hvtImg" /> <br /> <asp:Literal runat="server" ID="ltlTips" /> </div> </form> </body> </html>
页面所对应的代码
using System; namespace HoverTreeMobile { public partial class GetPictureByUrl : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void btnImg_Click(object sender, EventArgs e) { try { System.Net.WebClient m_hvtWebClient = new System.Net.WebClient(); //如果不是指定格式图片 //例如http://hovertree.com/hvtart/bjae/t2lo8pf7.htm 是htm文件，不是图片 if (!(textBoxImgUrl.Text.EndsWith(".jpg") || textBoxImgUrl.Text.EndsWith(".gif") || textBoxImgUrl.Text.EndsWith(".png"))) { ltlTips.Text = "输入的不是指定格式的图片的网址"; return; } //生成随机的图片文件名 string m_picFileName = HoverTree.HoverTreeFrame.Utils.GetHoverTreeString()+ HoverTree.HoverTreeFrame.HoverString.GetLastStr(textBoxImgUrl.Text,4); string m_keleyiPicture = Server.MapPath("/hovertreeimages/"+ m_picFileName); //根据网址下载文件 m_hvtWebClient.DownloadFile(textBoxImgUrl.Text, m_keleyiPicture); hvtImg.ImageUrl = "/hovertreeimages/" + m_picFileName; ltlTips.Text = string.Empty; } catch(Exception ex) { ltlTips.Text = ex.ToString(); } } } }
//生成随机的图片文件名
string m_picFileName = HoverTree.HoverTreeFrame.Utils.GetHoverTreeString()+ HoverTree.HoverTreeFrame.HoverString.GetLastStr(textBoxImgUrl.Text,4);
以上代码，请下载源代码查看详细实现方法。部分可到 LINK 查看。
HoverTree 开源项目：新增根据网址把图片下载到服务器功能
请看 HoverTreeMobile 项目，http://hovertree.com，何问起，源代码下载 LINK。
三、网页相关的方式
方法1：
public partial class DownLoadFile : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string picName = Request.QueryString["InternalSysURL"]; if (!String.IsNullOrEmpty(picName)) { byte[] content = this.GetImageContent(picName); this.WriteResponse(picName, content); } } #region private byte[] GetImageContent(string picName) { string fileURL = GetImgUrlPrefix() + picName; HttpWebRequest request = (HttpWebRequest)WebRequest.Create(fileURL); request.AllowAutoRedirect = true; WebProxy proxy = new WebProxy(); proxy.BypassProxyOnLocal = true; proxy.UseDefaultCredentials = true; request.Proxy = proxy; WebResponse response = request.GetResponse(); using (Stream stream = response.GetResponseStream()) { using (MemoryStream ms = new MemoryStream()) { Byte[] buffer = new Byte[1024]; int current = 0; while ((current = stream.Read(buffer, 0, buffer.Length)) != 0) { ms.Write(buffer, 0, current); } return ms.ToArray(); } } } private void WriteResponse(string picName, byte[] content) { Response.Clear(); Response.ClearHeaders(); Response.Buffer = false; Response.ContentType = "application/octet-stream"; Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(picName, Encoding.Default)); Response.AppendHeader("Content-Length", content.Length.ToString()); Response.BinaryWrite(content); Response.Flush(); Response.End(); } private static string GetImgUrlPrefix() { XmlDocument xmlDoc = new XmlDocument(); xmlDoc.Load(AppDomain.CurrentDomain.BaseDirectory + "//Pages//ItemMaintain//ImageDownLoad.xml"); XmlNodeList nodes = xmlDoc.GetElementsByTagName("ProductImageOriginal"); if (nodes.Count > 0) { return nodes[0].ChildNodes[0].Value; } else { return ""; } } #endregion }
方法2[3]：
根据URL请求获取页面HTML代码
/// <summary> /// 获取网页的HTML码 /// </summary> /// <param name="url">链接地址</param> /// <param name="encoding">编码类型</param> /// <returns></returns> public static string GetHtmlStr(string url, string encoding) { string htmlStr = ""; if (!String.IsNullOrEmpty(url)) { WebRequest request = WebRequest.Create(url); //实例化WebRequest对象 WebResponse response = request.GetResponse(); //创建WebResponse对象 Stream datastream = response.GetResponseStream(); //创建流对象 Encoding ec = Encoding.Default; if (encoding == "UTF8") { ec = Encoding.UTF8; } else if (encoding == "Default") { ec = Encoding.Default; } StreamReader reader = new StreamReader(datastream, ec); htmlStr = reader.ReadToEnd(); //读取数据 reader.Close(); datastream.Close(); response.Close(); } return htmlStr; }
下载网站图片
/// <summary>
/// 下载网站图片
/// </summary>
/// <param name="picUrl"></param>
/// <returns></returns>
public string SaveAsWebImg(string picUrl)
{
string result = "";
string path = AppDomain.CurrentDomain.SetupInformation.ApplicationBase + @"/File/"; //目录
try
{
if (!String.IsNullOrEmpty(picUrl))
{
Random rd = new Random();
DateTime nowTime = DateTime.Now;
string fileName = nowTime.Month.ToString() + nowTime.Day.ToString() + nowTime.Hour.ToString() + nowTime.Minute.ToString() + nowTime.Second.ToString() + rd.Next(1000, 1000000) + ".jpeg";
WebClient webClient = new WebClient();
webClient.DownloadFile(picUrl, path + fileName);
result = fileName;
}
}
catch { }
return result;
}
参考文章