HttpWebRequest和WebClient的区别

 HttpWebRequest和WebClient的区别(From Linzheng)：

1,HttpWebRequest是个抽象类，所以无法new的，需要调用HttpWebRequest.Create();
2,其Method指定了请求类型，这里用的GET,还有POST；也可以指定ConentType;
3,其请求的Uri必须是绝对地址;
4,其请求是异步回调方式的，从BeginGetResponse开始，并通过AsyncCallback指定回调方法；
5,WebClient 方式使用基于事件的异步编程模型,在HTTP响应返回时引发的WebClient回调是在UI线程中调用的，因此可用于更新UI元素的属性，例如把 HTTP响应中的数据绑定到UI的指定控件上进行显示。HttpWebRequest是基于后台进程运行的，回调不是UI线程，所以不能直接对UI进行操作，通常使用Dispatcher.BeginInvoke()跟界面进行通讯。

 //body是要传递的参数,格式"roleId=1&uid=2"
 //post的cotentType填写:
 //"application/x-www-form-urlencoded"
 //soap填写:"text/xml; charset=utf-8"
 public static string PostHttp(string url, string body, string contentType)
 {
 HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url);

 httpWebRequest.ContentType = contentType;
 httpWebRequest.Method = "POST";
 httpWebRequest.Timeout = ;

 byte[] btBodys = Encoding.UTF8.GetBytes(body);
 httpWebRequest.ContentLength = btBodys.Length;
 httpWebRequest.GetRequestStream().Write(btBodys, , btBodys.Length);

 HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
 StreamReader streamReader = new StreamReader(httpWebResponse.GetResponseStream());
 string responseContent = streamReader.ReadToEnd();

 httpWebResponse.Close();
 streamReader.Close();
 httpWebRequest.Abort();
 httpWebResponse.Close();

 return responseContent;
 }

 POST方法(httpWebRequest)

 /// <summary>
 /// 通过WebClient类Post数据到远程地址，需要Basic认证；
 /// 调用端自己处理异常
 /// </summary>
 /// <param name="uri"></param>
 /// <param name="paramStr">name=张三&age=20</param>
 /// <param name="encoding">请先确认目标网页的编码方式</param>
 /// <param name="username"></param>
 /// <param name="password"></param>
 /// <returns></returns>
 public static string Request_WebClient(string uri, string paramStr, Encoding encoding, string username, string password)
 {
 if (encoding == null)
 encoding = Encoding.UTF8;

 string result = string.Empty;

 WebClient wc = new WebClient();

 // 采取POST方式必须加的Header
 wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

 byte[] postData = encoding.GetBytes(paramStr);

 if (!string.IsNullOrEmpty(username) && !string.IsNullOrEmpty(password))
 {
 wc.Credentials = GetCredentialCache(uri, username, password);
 wc.Headers.Add("Authorization", GetAuthorization(username, password));
 }

 byte[] responseData = wc.UploadData(uri, "POST", postData); // 得到返回字符流
 return encoding.GetString(responseData);// 解码
 }

 POST方法(WebClient)

 public static string GetHttp(string url, HttpContext httpContext)
 {
 string queryString = "?";

 foreach (string key in httpContext.Request.QueryString.AllKeys)
 {
 queryString += key + "=" + httpContext.Request.QueryString[key] + "&";
 }

 queryString = queryString.Substring(, queryString.Length - );

 HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url + queryString);

 httpWebRequest.ContentType = "application/json";
 httpWebRequest.Method = "GET";
 httpWebRequest.Timeout = ;

 //byte[] btBodys = Encoding.UTF8.GetBytes(body);
 //httpWebRequest.ContentLength = btBodys.Length;
 //httpWebRequest.GetRequestStream().Write(btBodys, 0, btBodys.Length);

 HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
 StreamReader streamReader = new StreamReader(httpWebResponse.GetResponseStream());
 string responseContent = streamReader.ReadToEnd();

 httpWebResponse.Close();
 streamReader.Close();

 return responseContent;
 }

 Get方法(HttpWebRequest)

 /// <summary>
 /// 通过 WebRequest/WebResponse 类访问远程地址并返回结果，需要Basic认证；
 /// 调用端自己处理异常
 /// </summary>
 /// <param name="uri"></param>
 /// <param name="timeout">访问超时时间，单位毫秒；如果不设置超时时间，传入0</param>
 /// <param name="encoding">如果不知道具体的编码，传入null</param>
 /// <param name="username"></param>
 /// <param name="password"></param>
 /// <returns></returns>
 public static string Request_WebRequest(string uri, int timeout, Encoding encoding, string username, string password)
 {
 string result = string.Empty;

 WebRequest request = WebRequest.Create(new Uri(uri));

 if (!string.IsNullOrEmpty(username) && !string.IsNullOrEmpty(password))
 {
 request.Credentials = GetCredentialCache(uri, username, password);
 request.Headers.Add("Authorization", GetAuthorization(username, password));
 }

 if (timeout > )
 request.Timeout = timeout;

 WebResponse response = request.GetResponse();
 Stream stream = response.GetResponseStream();
 StreamReader sr = encoding == null ? new StreamReader(stream) : new StreamReader(stream, encoding);

 result = sr.ReadToEnd();

 sr.Close();
 stream.Close();

 return result;
 }

 #region # 生成 Http Basic 访问凭证 #

 private static CredentialCache GetCredentialCache(string uri, string username, string password)
 {
 string authorization = string.Format("{0}:{1}", username, password);

 CredentialCache credCache = new CredentialCache();
 credCache.Add(new Uri(uri), "Basic", new NetworkCredential(username, password));

 return credCache;
 }

 private static string GetAuthorization(string username, string password)
 {
 string authorization = string.Format("{0}:{1}", username, password);

 return "Basic " + Convert.ToBase64String(new ASCIIEncoding().GetBytes(authorization));
 }

 #endregion

 basic验证的WebRequest/WebResponse

备注：引自  http://www.cnblogs.com/shadowtale/p/3372735.html