用正则表达式自动下载网页中的图片
首先获得网页的Html代码，然后用正则表达式分析其中图片的下载地址，最后自动逐个下载。
using System.Net;
//// <summary>
/// Download Image from website
/// better to put into threads
/// </summary>
private void DownloadImage()
{
WebClient c = new WebClient();
//Get html code
string content = c.DownloadString(Uri);
Collection<string> address = new Collection<string>();
Collection<string> name = new Collection<string>();
//Analyse html code to get images address(Uri) and (Name) list
ParseHtml(content, Prefix, PicUriPrefix + @"(?<Uri>[^""]*?)"">(?<Name>[^<]*?)</dt>", address, name);
if (address.Count > 0 && name.Count > 0 && address.Count == name.Count)
{
if (Directory.Exists(folder) == false) Directory.CreateDirectory(folder);//Create folder
foreach (string add in address)
{
//Download images one by one
c.DownloadFile(add, Path.Combine(folder, name[address.IndexOf(add)] + ".jpg"));
}
}
}
/// <summary>
/// Parse Html using regular expressions
/// </summary>
/// <param name="content">Html content</param>
/// <param name="prefix">Uri prefix</param>
/// <param name="expression">regular expression</param>
/// <param name="address">Image addresses collection</param>
/// <param name="name">Image names collection</param>
private void ParseHtml(string content, string prefix, string expression, Collection<string> address, Collection<string> name)
{
if (String.IsNullOrEmpty(expression) || address == null || name == null) return;
Regex re = new Regex(expression, RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.RightToLeft);
MatchCollection mc = re.Matches(content);
if (mc == null || mc.Count == 0) return;
foreach (Match m in mc)
{
address.Add(prefix + m.Groups["Uri"].Value);
name.Add(m.Groups["Name"].Value);
}
}
Html部分代码如下：
Html code
要用正则表达式从中获得图片下载地址（例如：/docfile/dyn/12345678LANGCCCCDDDDEEEEEEEERT09）和图片名称（例如：BMW 3-series）
正则表达式部分如下：
Regular expression
using System.Net; //// <summary> /// Download Image from website /// better to put into threads /// </summary> private void DownloadImage() {
WebClient c = new WebClient(); //Get html code string content = c.DownloadString(Uri); Collection<string> address = new Collection<string>(); Collection<string> name = new Collection<string>(); //Analyse html code to get images address(Uri) and (Name) list ParseHtml(content, Prefix, PicUriPrefix + @"(?<Uri>[^""]*?)"">(?<Name>[^<]*?)</dt>", address, name); if (address.Count > 0 && name.Count > 0 && address.Count == name.Count) {
if (Directory.Exists(folder) == false) Directory.CreateDirectory(folder);//Create folder foreach (string add in address) { //Download images one by one c.DownloadFile(add, Path.Combine(folder, name[address.IndexOf(add)] + ".jpg")); } } } /// <summary> /// Parse Html using regular expressions /// </summary> /// <param name="content">Html content</param> /// <param name="prefix">Uri prefix</param> /// <param name="expression">regular expression</param> /// <param name="address">Image addresses collection</param> /// <param name="name">Image names collection</param> private void ParseHtml(string content, string prefix, string expression, Collection<string> address, Collection<string> name) { if (String.IsNullOrEmpty(expression) || address == null || name == null) return; Regex re = new Regex(expression, RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.RightToLeft); MatchCollection mc = re.Matches(content); if (mc == null || mc.Count == 0) return; foreach (Match m in mc) { address.Add(prefix + m.Groups["Uri"].Value); name.Add(m.Groups["Name"].Value); } } Html部分代码如下：
Html code要用正则表达式从中获得图片下载地址（例如：/docfile/dyn/12345678LANGCCCCDDDDEEEEEEEERT09）和图片名称（例如：BMW 3-series）
正则表达式部分如下：
Regular expression注意其中group的用法(? *?)，和引号的匹配用法，匹配双引号前面需要再带一个双引号。其中Uri这个group在dyn/后面，直到双引号结束；后面跟随着双引号和>，然后就是Name这个group；它以<号结束，最后跟随</dt>。
本文引用于:http://www.cnblogs.com/Mainz/articles/1087460.html
