C ＃ three ways to obtain web page content

C# Three ways to get web content

Search the web , Find out C# There are usually three ways to get web content , Use WebClient、WebBrowser perhaps HttpWebRequest/HttpWebResponse...

Method 1 ： Use WebClient （ Quote from ：http://fbljava.blog.163.com/blog/static/265211742008712105145244/）

static void Main(string[] args)

{

    try {

        WebClient MyWebClient = new WebClient();

        
        MyWebClient.Credentials = CredentialCache.DefaultCredentials;// Gets or sets the value used to Internet Network credentials for authentication of resource requests

        Byte[] pageData = MyWebClient.DownloadData(“http://www.163.com”); // Download data from the specified website

        string pageHtml = Encoding.Default.GetString(pageData);  // If you get the website page using GB2312, Use this sentence             

        //string pageHtml = Encoding.UTF8.GetString(pageData); // If you get the website page using UTF-8, Use this sentence

        Console.WriteLine(pageHtml);// Enter the acquired content in the console

        using (StreamWriter sw = new StreamWriter("c:\\test\\ouput.html"))// Write the acquired content into the text

        {

            sw.Write(pageHtml);

        }

        Console.ReadLine(); // Let the console pause , Otherwise, it will flash by              

    }

    catch(WebException webEx) {

        Console.WriteLine(webEx.Message.ToString());

    }

}

Method 2 ： Use WebBrowser （ Quote from ：http://topic.csdn.net/u/20091225/14/4ea221cd-4c1e-4931-a6db-1fd4ee7398ef.html）

WebBrowser web = new WebBrowser(); 
web.Navigate("http://www.xjflcp.com/ssc/"); 
web.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(web_DocumentCompleted); 
void web_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) 
        { 
            WebBrowser web = (WebBrowser)sender; 
            HtmlElementCollection ElementCollection = web.Document.GetElementsByTagName("Table"); 
            foreach (HtmlElement item in ElementCollection) 
            { 
                 File.AppendAllText("Kaijiang_xj.txt", item.InnerText); 
            } 
        }

Method 3 ： Use HttpWebRequest/HttpWebResponse （ Quote from ：http://hi.baidu.com/onlyafar/blog/item/7ac4c6bf92d4810019d81f98.html）

HttpWebRequest httpReq; 
HttpWebResponse httpResp; 

string strBuff = ""; 
char[] cbuffer = new char[256]; 
int byteRead = 0; 

string filename = @"c:\log.txt"; 
/// Define write stream operations  
public void WriteStream() 
{ 
Uri httpURL = new Uri(txtURL.Text);

///HttpWebRequest Class inherited from WebRequest, Does not have its own constructor , Need to pass WebRequest Of Creat Method establish , And perform forced type conversion  
      httpReq = (HttpWebRequest)WebRequest.Create(httpURL); 
/// adopt HttpWebRequest Of GetResponse() Method establishment HttpWebResponse, Cast

   httpResp = (HttpWebResponse) httpReq.GetResponse(); 
///GetResponseStream() Method to get HTTP The data flow of the response , And try to get URL Page content specified in

     /// If you succeed in getting the content of the web page , with System.IO.Stream returns , If it fails, there will be ProtoclViolationException wrong By mistake . The right way to do this is to put the following code in one try Processing in blocks . It's easy to deal with  
Stream respStream = httpResp.GetResponseStream();

/// The content returned is Stream Formal , So we can use StreamReader Class gets GetResponseStream The content of , And

StreamReader Class Read Method to read the content of each line of the web page source code in turn , To the end of the line （ Read the encoding format ：UTF8） 
StreamReader respStreamReader = new StreamReader(respStream,Encoding.UTF8);

byteRead = respStreamReader.Read(cbuffer,0,256); 

while (byteRead != 0) 
{ 
string strResp = new string(cbuffer,0,byteRead); 
                  strBuff = strBuff + strResp; 
                  byteRead = respStreamReader.Read(cbuffer,0,256); 
} 

respStream.Close(); 
txtHTML.Text = strBuff; 
}

Pro test example ：

 /// <summary>
    /// Access to web pages Html data
    /// </summary>
    protected void GetWebData()
    {
        Debug.Log("Getting web data...");
        try
        {
            byte[] pageData = myWebClient.DownloadData(url);
            string html = Encoding.UTF8.GetString(pageData);


            Debug.Log("Gat web data.");


            if (!string.IsNullOrEmpty(html))
            {
                Debug.Log("Web data is not null!");
                Debug.Log("html" + html);


                string startTag = "<body>";
                string endTag = "</body>";


                int start = html.IndexOf(startTag);
                int end = html.IndexOf(endTag);


                if (start > 0 && end > 0 && end > start)
                {
                    Debug.Log("Data is not null!");


                    int len1 = start + startTag.Length;
                    string body = html.Substring(len1, end - len1);
                    Debug.Log("body:" + body);              
                }
                else
                    Debug.Log("Data is null!");
            }
            else
                Debug.Log("Web data is null!");
        }
        catch
        {
            Debug.Log("Not get web data!");
        }
    }

This article is only for learning and reference ！ Please correct me if there is any mistake ！