C# HttpWebRequest和WebClient的區別 通過WebClient/HttpWebRequest實現http的post/get方法

一 HttpWebReques
1,HttpWebRequest是個抽象類，所以無法new的，需要調用HttpWebRequest.Create();
2,其Method指定了請求類型，這里用的GET,還有POST；也可以指定ConentType;
3,其請求的Uri必須是絕對地址;
4,其請求是異步回調方式的，從BeginGetResponse開始，並通過AsyncCallback指定回調方法；
二 WebClient
1,WebClient 方式使用基於事件的異步編程模型,在HTTP響應返回時引發的WebClient回調是在UI線程中調用的，因此可用於更新UI元素的屬性，
例如把 HTTP響應中的數據綁定到UI的指定控件上進行顯示。HttpWebRequest是基於后台進程運行的，回調不是UI線程，所以不能直接對UI進行操作，通常使用Dispatcher.BeginInvoke()跟界面進行通訊。

//body是要傳遞的參數,格式"roleId=1&uid=2"
//post的cotentType填寫:
//"application/x-www-form-urlencoded"
//soap填寫:"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 = 20000;

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

        return responseContent;
    }

POST方法(httpWebRequest)

/// <summary>
        /// 通過WebClient類Post數據到遠程地址，需要Basic認證；
        /// 調用端自己處理異常
        /// </summary>
        /// <param name="uri"></param>
        /// <param name="paramStr">name=張三&age=20</param>
        /// <param name="encoding">請先確認目標網頁的編碼方式</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方式必須加的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);// 解碼                  
        }

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(0, queryString.Length - 1);

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

        httpWebRequest.ContentType = "application/json";
        httpWebRequest.Method = "GET";
        httpWebRequest.Timeout = 20000;

        //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>
        /// 通過 WebRequest/WebResponse 類訪問遠程地址並返回結果，需要Basic認證；
        /// 調用端自己處理異常
        /// </summary>
        /// <param name="uri"></param>
        /// <param name="timeout">訪問超時時間，單位毫秒；如果不設置超時時間，傳入0</param>
        /// <param name="encoding">如果不知道具體的編碼，傳入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 > 0)
                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 訪問憑證 #

        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驗證的WebRequest/WebResponse