微信下载远程图片的公用方法

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Runtime.Serialization.Json;
using System.Text;
using System.Text.RegularExpressions;

namespace Wisdom.JPClient.WeiXin.Utility
{
    public class CommonUtility
    {
        public static bool IsGUID(string str)
        {
            Match m = Regex.Match(str, @"^[0-9a-f]{8}(-[0-9a-f]{4}){3}-[0-9a-f]{12}$", RegexOptions.IgnoreCase);
            if (m.Success)
            {
                //可以转换 
                //Guid guid = new Guid(str);
                return true;
            }
            else
            {
                //不可转换 
                return false;
            }
        }

        /// <summary>
        /// 获取远程图片
        /// </summary>
        /// <param name="imgUrl">远程图片地址</param>
        /// <param name="path">文件夹名</param>
        /// <returns></returns>
        public static int SaveImageFromWeb(string imgUrl, string Pic_Path_IDCard, ref string NewPicName)
        {
            NewPicName = DateTime.Now.ToString("yyyyMMddHHmmss") + new Random().Next(10, 100);
            var aaa = Environment.CurrentDirectory;
            string imgName = imgUrl.ToString().Substring(imgUrl.ToString().LastIndexOf("/") + 1);
            if (Directory.Exists(System.Web.HttpContext.Current.Server.MapPath("~/UploadFiles/" + Pic_Path_IDCard + "/")) == false)//如果不存在就创建file文件夹
            {
                Directory.CreateDirectory(System.Web.HttpContext.Current.Server.MapPath("~/UploadFiles/" + Pic_Path_IDCard + "/"));
            }
            string path = System.Web.HttpContext.Current.Server.MapPath(String.Format("/UploadFiles/" + Pic_Path_IDCard + "/{0}", NewPicName));
            //path = path + "//" + imgName;
            string defaultType = ".jpg";
            string[] imgTypes = new string[] { ".jpg", ".jpeg", ".png", ".gif", ".bmp" };
            string imgType = imgUrl.ToString().Substring(imgUrl.ToString().LastIndexOf("."));
            foreach (string it in imgTypes)
            {
                if (imgType.ToLower().Equals(it))
                    break;
                if (it.Equals(".bmp"))
                    imgType = defaultType;
            }
            try
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(imgUrl);
                request.UserAgent = "Mozilla/6.0 (MSIE 6.0; Windows NT 5.1; Natas.Robot)";
                request.Timeout = 10000;
                WebResponse response = request.GetResponse();
                Stream stream = response.GetResponseStream();
                if (response.ContentType.ToLower().StartsWith("image/"))
                {
                    byte[] arrayByte = new byte[1024];
                    int imgLong = (int)response.ContentLength;
                    int l = 0;
                    // CreateDirectory(path);
                    FileStream fso = new FileStream(path, FileMode.Create);
                    while (l < imgLong)
                    {
                        int i = stream.Read(arrayByte, 0, 1024);
                        fso.Write(arrayByte, 0, i);
                        l += i;
                    }
                    fso.Close();
                    stream.Close();
                    response.Close();
                    return 1;
                }
                else
                {
                    return 0;
                }
            }
            catch (WebException)
            {
                return 0;
            }
            catch (UriFormatException)
            {
                return 0;
            }
        }

        /// <summary>
        /// 返回中文周几，
        /// </summary>
        /// <param name="y">年</param>
        /// <param name="m">月</param>
        /// <param name="d">日</param>
        /// <returns></returns>
        public static string CaculateChineseWeekDay(int y, int m, int d)
        {
            if (m == 1) m = 13;
            if (m == 2) m = 14;
            int week = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400) % 7 + 1;
            string weekstr = "";
            switch (week)
            {
                case 1: weekstr = "周一"; break;
                case 2: weekstr = "周二"; break;
                case 3: weekstr = "周三"; break;
                case 4: weekstr = "周四"; break;
                case 5: weekstr = "周五"; break;
                case 6: weekstr = "周六"; break;
                case 7: weekstr = "周日"; break;
            }

            return weekstr;
        }




        /// <summary>
        /// 下载保存多媒体文件,返回多媒体保存路径
        /// </summary>
        /// <param name="ACCESS_TOKEN"></param>
        /// <param name="MEDIA_ID"></param>
        /// <returns></returns>
        public static string GetMultimedia(string ACCESS_TOKEN, string MEDIA_ID, string fileName, ref string NewPicName)
        {
            NewPicName = DateTime.Now.ToString("yyyyMMddHHmmss") + new Random().Next(10, 100) + ".jpg";
            string file = string.Empty;
            string content = string.Empty;
            string strpath = string.Empty;
            string savepath = string.Empty;
            string stUrl = "http://file.api.weixin.qq.com/cgi-bin/media/get?access_token=" + ACCESS_TOKEN + "&media_id=" + MEDIA_ID;

            if (Directory.Exists(System.Web.HttpContext.Current.Server.MapPath("~/UploadFiles/" + fileName + "/")) == false)//如果不存在就创建file文件夹
            {
                Directory.CreateDirectory(System.Web.HttpContext.Current.Server.MapPath("~/UploadFiles/" + fileName + "/"));
            }

            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(stUrl);

            req.Method = "GET";
            using (WebResponse wr = req.GetResponse())
            {
                HttpWebResponse myResponse = (HttpWebResponse)req.GetResponse();

                strpath = myResponse.ResponseUri.ToString();
                WebClient mywebclient = new WebClient();
                savepath = System.Web.HttpContext.Current.Server.MapPath(String.Format("/UploadFiles/" + fileName + "/{0}", NewPicName));
                try
                {
                    mywebclient.DownloadFile(strpath, savepath);
                    file = savepath;
                }
                catch (Exception ex)
                {
                    savepath = ex.ToString();
                }

            }
            return file;
        }



        ///   <summary> 
        ///   将指定字符串按指定长度进行截取并加上指定的后缀
        ///   </summary> 
        ///   <param   name= "oldStr "> 需要截断的字符串 </param> 
        ///   <param   name= "maxLength "> 字符串的最大长度 </param> 
        ///   <param   name= "endWith "> 超过长度的后缀 </param> 
        ///   <returns> 如果超过长度，返回截断后的新字符串加上后缀，否则，返回原字符串 </returns> 
        public static string StringTruncat(string oldStr, int maxLength, string endWith)
        {
            //判断原字符串是否为空
            if (string.IsNullOrEmpty(oldStr))
                return oldStr + endWith;


            //返回字符串的长度必须大于1
            if (maxLength < 1)
                throw new Exception("返回的字符串长度必须大于[0] ");


            //判断原字符串是否大于最大长度
            if (oldStr.Length > maxLength)
            {
                //截取原字符串
                string strTmp = oldStr.Substring(0, maxLength);


                //判断后缀是否为空
                if (string.IsNullOrEmpty(endWith))
                    return strTmp;
                else
                    return strTmp + endWith;
            }
            return oldStr;
        }

        /// <summary>
        /// post方法
        /// </summary>
        /// <param name="postUrl">url地址</param>
        /// <param name="paramData">提交的ParamData对象</param>
        /// <returns></returns>
        public static string PostWebRequest<T>(string postUrl, T paramData)
        {
            string ret = string.Empty;
            try
            {
                string str_Tem = JsonConvert.SerializeObject(paramData);//将对象转成json串
                byte[] byteArray = System.Text.Encoding.UTF8.GetBytes(str_Tem);
                HttpWebRequest webReq = (HttpWebRequest)WebRequest.Create(new Uri(postUrl));
                webReq.Method = "POST";
                webReq.ContentType = " application/json; charset=utf-8";
                webReq.ContentLength = byteArray.Length;
                Stream newStream = webReq.GetRequestStream();
                newStream.Write(byteArray, 0, byteArray.Length);//写入参数
                newStream.Close();
                HttpWebResponse response = (HttpWebResponse)webReq.GetResponse();
                StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                ret = sr.ReadToEnd();
                sr.Close();
                response.Close();
                newStream.Close();
            }
            catch (Exception ex)
            {

            }
            return ret;
        }

        /// <summary>
        /// C#反序列化JSON
        /// </summary>
        /// <typeparam name="T">返回类型</typeparam>
        /// <param name="jsonString">JSON字符串</param>
        /// <returns></returns>
        public static T JsonDeserialize<T>(string strJson)
        {
            DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
            MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(strJson));
            T objT = (T)ser.ReadObject(ms);
            ms.Close();
            return objT;
        }
    }
}