Download Web Content other than using WebClient class

Keywords: WebClient, UTF-8, WebRequest

从一个URI上下载网页Content或Xml, 可以直接使用WebClient类(在System.Net命名空间), 非常简单. 它有很多Download方法, 比如DownloadString()和DownloadFile(). 这些都是同步方法, 当然它也有异步Download方法, 不过经常用的是它的同步方法.

但在用WebClient.DownloadString()一个以UTF-8编码格式存盘的一个Xml文件时, 得到的Xml字符串有乱码, 不管怎样设置WebClient的Encode属性都没有用处, 可能是WebClient的一个bug吧.

可以WebRequest方法来实现同步DownloadString的功能. 代码如下:

        public void DownloadAndLoadXml(string uri, XmlDocument doc)
        {
            System.Net.WebRequest request = System.Net.WebRequest.Create(uri);
            using (System.Net.WebResponse response=request.GetResponse())
            using (System.IO.Stream stream=response.GetResponseStream())
            {
                if (stream.Length > 0)
                {
                    stream.Position = 0;
                    doc.Load(stream);
                }
            }
        }

        /// <summary>
        /// download the web page from the given uri
        /// </summary>
        /// <param name="uri"></param>
        /// <returns></returns>
        public string DownloadStringFromWeb(string uri)
        {
            System.Net.WebRequest request = System.Net.WebRequest.Create(uri);
            using (System.Net.WebResponse response = request.GetResponse())
            using (System.IO.Stream stream = response.GetResponseStream())
            {
                System.IO.StreamReader reader = new StreamReader(stream);
                //save all info from stream into a string variable 
                string result=reader.ReadToEnd();
                reader.Close();
                return result;
            }
        }