[转]DownloadImage

using System;
2using System.Collections.Generic;
3using System.Linq;
4using System.Text;
5using System.IO;
6
7namespace DownloadImagebyXMLListFor2008 8{
9    public class HttpDownLoad
10    {
11        /**//// <summary>
12        /// HttpWebRequest Property
13        /// </summary>
14        /// <param name="fileName"></param>
15        /// <param name="url"></param>
16        /// <param name="localPath"></param>
17        /// <param name="timeout"></param>
18        public static void DownloadOneFileByURL(string fileName, string url, string localPath, int timeout)
19        {
20            System.Net.HttpWebRequest request = null;
21            System.Net.HttpWebResponse response = null;
22            request = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(url + fileName);
23            request.Timeout = timeout;//8000 Not work ?
24            response = (System.Net.HttpWebResponse)request.GetResponse();
25            Stream s = response.GetResponseStream();
26            BinaryReader br = new BinaryReader(s);
27            //int length2 = Int32.TryParse(response.ContentLength.ToString(), out 0);
28            int length2 = Int32.Parse(response.ContentLength.ToString());
29            byte[] byteArr = new byte[length2];
30            s.Read(byteArr, 0, length2);
31            if (File.Exists(localPath + fileName)) { File.Delete(localPath + fileName); }
32            if (Directory.Exists(localPath) == false) { Directory.CreateDirectory(localPath); }
33            FileStream fs = File.Create(localPath + fileName);
34            fs.Write(byteArr, 0, length2);
35            fs.Close();
36            br.Close();
37        }
38        /**//// <summary>
39        ///Web Client Method ,only For Small picture
40        /// </summary>
41        /// <param name="fileName"></param>
42        /// <param name="url"></param>
43        /// <param name="localPath"></param>
44        public static void DownloadOneFileByURLWithWebClient(string fileName, string url, string localPath)
45        {
46            System.Net.WebClient wc = new System.Net.WebClient();
47            if (File.Exists(localPath + fileName)) { File.Delete(localPath + fileName); }
48            if (Directory.Exists(localPath) == false) { Directory.CreateDirectory(localPath); }
49            wc.DownloadFile(url + fileName, localPath + fileName);
50        }
51    }
52}

需要注意点：
第一　DownloadOneFileByURL方法，有时会下载不了文件，如果文件大于40K就更明显，DownloadOneFileByURLWithWebClient则无此问题。
第二　调用时请用Thread,给出一个示例

1 private void btnGet_Click(object sender, EventArgs e)
2        {
3            if (txtTempFile.Text.Trim().Length == 0)
4            {
5                ErrorStop("列表文件为空！"); return;
6            }
7            System.Threading.Thread thread = new System.Threading.Thread(new System.Threading.ThreadStart(DownloadAll));
8            thread.Start();
9        }
10 private void DownloadAll()
11        {
12            List<string> ls = GetStringsByFile(txtTempFile.Text.Trim());
13            if (null != ls)
14            {
15
16                foreach (string s in ls)
17                {
18                    try
19                    {
20                        //HttpDownLoad.DownloadOneFileByURL(s, Globals.HttpPreUrl, Globals.LocalPrePath, 8000000);
21                        HttpDownLoad.DownloadOneFileByURLWithWebClient(s, Globals.HttpPreUrl, Globals.LocalPrePath);
22                    }
23                    catch { continue; }
24                }
25            }
26        }