開發時總會需要用到線上功能，這時候就需要使用http request來收發資訊。
本文講述如何在C#中操作連線問題，並且做訊息收發(GET,POST)。
GET
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string targetUrl = "http://localhost:8080/Request/getTest?value=1"; HttpWebRequest request = HttpWebRequest.Create(targetUrl) as HttpWebRequest; request.Method = "GET"; request.ContentType = "application/x-www-form-urlencoded"; request.Timeout = 3000; string result = ""; // 取得回應資料 using (HttpWebResponse response = request.GetResponse() as HttpWebResponse) { using (StreamReader sr = new StreamReader(response.GetResponseStream())) { result = sr.ReadToEnd(); } } Response.Write(result); |
上方是利用GET方法向伺服器發送request，
其中target URL部分可依照使用者不同ip, port去做修改，也可做成動態string。
另外後方帶的API URL也可依照server API設計去做不同參數傳遞。
再來使用StreamReader將server回傳的資料讀出，並存入想要的參數中。
POST
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string targetUrl = "http://localhost:8080/Request/postTest"; string para = "p=Arvin"; byte[] postData = Encoding.UTF8.GetBytes(para); HttpWebRequest request = HttpWebRequest.Create(targetUrl) as HttpWebRequest; request.Method = "POST"; request.ContentType = "application/x-www-form-urlencoded"; request.Timeout = 3000; request.ContentLength = postData.Length; // 寫入 Post Body Message 資料流 using (Stream st = request.GetRequestStream()) { st.Write(postData, 0, postData.Length); } string result = ""; // 取得回應資料 using (HttpWebResponse response = request.GetResponse() as HttpWebResponse) { using (StreamReader sr = new StreamReader(response.GetResponseStream())) { result = sr.ReadToEnd(); } } Response.Write(result); |
與GET最大的不同是POST在request的同時會將資料傳遞至server上的目標API，server再針對傳入的資料做解析後，傳回相應的回應資料。
POST redirect
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string targetUrl = "http://localhost:8080/Request/postReTest"; string para = "url=http://localhost:8080/Request/default"; byte[] postData = Encoding.UTF8.GetBytes(HttpUtility.HtmlEncode(para)); HttpWebRequest request = HttpWebRequest.Create(targetUrl) as HttpWebRequest; request.Method = "POST"; request.ContentType = "application/x-www-form-urlencoded"; request.Timeout = 3000; request.ContentLength = postData.Length; request.AllowAutoRedirect = false; // 禁止重新導向網頁 // 寫入 Post Body Message 資料流 using (Stream st = request.GetRequestStream()) { st.Write(postData, 0, postData.Length); } string result = ""; // 取得回應資料 using (HttpWebResponse response = request.GetResponse() as HttpWebResponse) { if (response.StatusCode == HttpStatusCode.Found) // 判斷是否為 302 { // 取得返回的Header中的Location參數，Location函有重新導向的網址資訊 Uri redirectUrl = new Uri(response.Headers["Location"]); // 利用HttpUtility類別的ParseQueryString方法剖析QueryString參數 result = HttpUtility.ParseQueryString(redirectUrl.Query, Encoding.UTF8).Get("para"); } } Response.Write(result); |
首先為了避免被重新導向，所以要增加 request.AllowAutoRedirect = false 設定，當Server有重新導向動作時，response回來的StatusCode應該為302，302 有包含導向的Location，所以要取得 response 回來的 Header 資料中的 Location ，Location 將包含導向的URL位置及參數，最後利用HttpUtility類別的ParseQueryString方法剖析QueryString中要取得的參數即可。
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