ASP.NET获取网页中的图片

ASP.NET获取网页中的图片

下面介绍一个输入网址,获取该网址图片的ASP.NET方法

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  • C# 代码   复制
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    /// <summary>
        /// 下载指定URL下的所有图片
        /// </summary>
        public class WebPageImage
        {
            /// <summary>
            /// 获取网页中全部图片
            /// </summary>
            /// <param name="url">网页地址</param>
            /// <param name="charSet">网页编码,为空自动判断</param>
            /// <returns>全部图片显示代码</returns>
            public string getImages(string url, string charSet)
            {
                string s = getHtml(url, charSet);
                return getPictures(s, url);
            }
    
            /// <summary>
            /// 获取网页中全部图片
            /// </summary>
            /// <param name="url">网址</param>
            /// <returns>全部图片代码</returns>
            public string getImages(string url)
            {
                return getImages(url, "");
            }
    
            string doman(string url)
            {
                Uri u = new Uri(url);
                return u.Host;
            }
    
            /// <summary>
            /// 获取网页内容
            /// </summary>
            /// <param name="url">网站地址</param>
            /// <param name="charSet">目标网页的编码,如果传入的是null或者"",那就自动分析网页的编码 </param>
            /// <returns></returns>
            string getHtml(string url, string charSet)
            {
                WebClient myWebClient = new WebClient();
                //创建WebClient实例myWebClient 
                // 需要注意的: 
                //有的网页可能下不下来,有种种原因比如需要cookie,编码问题等等 
                //这是就要具体问题具体分析比如在头部加入cookie 
                // webclient.Headers.Add("Cookie", cookie); 
                //这样可能需要一些重载方法。根据需要写就可以了 
    
                //获取或设置用于对向 Internet 资源的请求进行身份验证的网络凭据。 
                myWebClient.Credentials = CredentialCache.DefaultCredentials;
                //如果服务器要验证用户名,密码 
                //NetworkCredential mycred = new NetworkCredential(struser, strpassword); 
                //myWebClient.Credentials = mycred; 
                //从资源下载数据并返回字节数组。(加@是因为网址中间有"/"符号) 
                byte[] myDataBuffer = myWebClient.DownloadData(url);
                string strWebData = Encoding.Default.GetString(myDataBuffer);
    
                //获取网页字符编码描述信息 
                Match charSetMatch = Regex.Match(strWebData, "<meta([^<]*)charset=([^<]*)\\"", RegexOptions.IgnoreCase | RegexOptions.Multiline);
                string webCharSet = charSetMatch.Groups[2].Value.Replace("\\"", "");
                if (charSet == null || charSet == "")
                    charSet = webCharSet;
    
                if (charSet != null && charSet != "" && Encoding.GetEncoding(charSet) != Encoding.Default)
                    strWebData = Encoding.GetEncoding(charSet).GetString(myDataBuffer);
                return strWebData;
            }
    
            string getPictures(string data, string url)
            {
                MatchCollection ps = Regex.Matches(data, @"<img\\b[^<>]*?\\bsrc[\\s\\t\\r\\n]*=[\\s\\t\\r\\n]*[""']?[\\s\\t\\r\\n]*(?<imgUrl>[^\\s\\t\\r\\n""'<>]*)[^<>]*?/?[\\s\\t\\r\\n]*>");
                string s = string.Empty;
                for (int i = 0; i < ps.Count; i++)
                {
                    pictures p = new pictures(ps[i].Value, url);
                    s += p.GetHtml + "<br />" + Environment.NewLine;
                }
                return s;
            }
    
            /// <summary>
            /// 图片实体
            /// 图片文件属性处理类
            /// </summary>
            public class pictures
            {
                public pictures(string strHtml, string baseUrl)
                {
                    _html = strHtml;
                    Uri u1 = new Uri(baseUrl);
                    _doman = u1.Host;
                    _baseUrl = u1.Scheme + "://" + _doman;
                    setSrc();
                }
    
                private string _html = string.Empty;
                private string _baseUrl = string.Empty;
                private string _doman = string.Empty;
    
                public string GetHtml
                {
                    get { return _html; }
                }
    
                public string Alt
                {
                    get
                    {
                        return GetAttribute("alt")[0];
                    }
                }
    
                public string Src
                {
                    get
                    {
                        string s = GetAttribute("src")[0];
                        return s;
                    }
                }
    
                /// <summary>
                /// 根据基路径把相对路径转换成绝对径
                /// </summary>
                /// <param name="baseUrl">基础路径</param>
                /// <param name="u">待转换的相对路径</param>
                /// <returns>绝对路径</returns>
                public string absUrl(string baseUrl, string u)
                {
                    Uri ub = new Uri(baseUrl);
                    Uri ua = new Uri(ub, u);
                    return ua.AbsoluteUri;
                }
    
                private void setSrc()
                {
                    string strPattern = @"src[\\s\\t\\r\\n]*=[\\s\\t\\r\\n]*[""']?\\S+[""']?";
                    string src = GetAttribute("src")[0].ToLower();
                    if (!(src.IndexOf("http://") == 0 || src.IndexOf("https://") == 0) && _baseUrl.Length > 10)
                    {
                        src = absUrl(_baseUrl, src);
                        string s = "src=\\"" + src + "\\"";
                        _html = Regex.Replace(_html, strPattern, s);
                    }
                }
    
                /// <summary>
                /// 获取HTML代码中标签属性
                /// </summary>
                /// <param name="strHtml">HTML代码</param>
                /// <param name="strAttributeName">属性名称</param>
                /// <returns>属性值集合</returns>
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