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ASP.NET Web API 应用教程（一） ——数据流使用

發(fā)布時(shí)間：2023/12/13 asp.net 21 豆豆

生活随笔收集整理的這篇文章主要介紹了 ASP.NET Web API 应用教程（一） ——数据流使用小編覺得挺不錯(cuò)的,現(xiàn)在分享給大家,幫大家做個(gè)參考.

相信已經(jīng)有很多文章來介紹ASP.Net Web API 技術(shù)，本系列文章主要介紹如何使用數(shù)據(jù)流，HTTPS，以及可擴(kuò)展的Web API 方面的技術(shù)，系列文章主要有三篇內(nèi)容。

主要內(nèi)容如下：

I ?數(shù)據(jù)流

II 使用HTTPS

III 可擴(kuò)展的Web API 文檔

項(xiàng)目環(huán)境要求

VS 2012（SP4）及以上，
.Net 框架4.5.1
Nuget包,可在packages.config 文件中查尋

本文涉及的知識(shí)點(diǎn)

ActionFilter

AuthorizationFilter

DelegateHandler

Different Web API routing 屬性

MediaTypeFormatter

OWIN

Self Hosting

Web API 文檔及可擴(kuò)展功能

.Net 框架

Async/Await

.NET reflection

Serialization

ASP.NET Web API/MVC Error handling

IIS ,HTTPS 及Certificate

設(shè)計(jì)準(zhǔn)則及技術(shù)

前言

自從ASP.NET MVC 4之后.Net 框架開始支持ASP.NET Web API ，ASP.NET Web API 基于HTTP 協(xié)議建立的，是構(gòu)建 RESTful 服務(wù)和處理數(shù)據(jù)的理想平臺(tái)，旨在使用HTTP 技術(shù)實(shí)現(xiàn)對(duì)多平臺(tái)的支持。

ASP.NET Web API 以request-response 的消息轉(zhuǎn)換模式為主，客戶端向服務(wù)器發(fā)送請(qǐng)求，服務(wù)器端響應(yīng)客戶端請(qǐng)求。響應(yīng)可同步或異步。

?個(gè)人認(rèn)為使用Web API創(chuàng)建應(yīng)用需要注意的三個(gè)關(guān)鍵點(diǎn)：

采用服務(wù)及方法滿足的目標(biāo)
每個(gè)方法的輸入，如請(qǐng)求
每個(gè)方法的輸出，如響應(yīng)

通常情況下，Asp.Net Web API 定義method語法與HTTP方法一一對(duì)應(yīng)的，如自定義方法名?GetPysicians()，則與HTTP中Get 方法匹配。下圖是常用匹配表。

但是此方法在很多情況下，并不實(shí)用，假如你想在單個(gè)API controller 類中定義多個(gè)Get 或Post 方法，在這種情況下，需要定義包含action 的路徑，將Action 作為URI 的一部分。以下是配置代碼：

1: public static void Register(HttpConfiguration config) 2: { 3: // Web API configuration and services 4: // Web API routes 5: config.MapHttpAttributeRoutes(); 6: 7: config.Routes.MapHttpRoute(name: "PhysicianApi", 8: routeTemplate: "{controller}/{action}/{id}", 9: defaults: new { id = RouteParameter.Optional }); 10: }

但是此方法不足以應(yīng)對(duì)所有情況，如果想實(shí)現(xiàn)從中央倉庫刪除文件，并且想調(diào)用同一個(gè)方法來獲取文件，這種情況下，Web API 框架需要偽裝Get 及Delete對(duì)應(yīng)的HTTP 方法屬性。如圖所示：

RemoveFile 方法可被Delete(HttpDelete) 或 Get(HttpGet)方法同時(shí)調(diào)用，從某種程度來說，HTTP 方法使開發(fā)人員命名?API“方法”變得簡單而標(biāo)準(zhǔn)。

Web API框架也提供了一些其他功能來處理路徑方面的問題，與MVC 的路徑處理方法相似。因此可定義不同類型的Action方法。?

數(shù)據(jù)流

網(wǎng)絡(luò)App 最常見的執(zhí)行操作就是獲取數(shù)據(jù)流。ASP.NET Web API 能夠處理客戶端與服務(wù)器端傳輸?shù)闹亓考?jí)的數(shù)據(jù)流，數(shù)據(jù)流可來源于目錄文件，也可是數(shù)據(jù)庫中的二進(jìn)制文件。本文主要介紹兩種方法“Download”和“Upload”實(shí)現(xiàn)數(shù)據(jù)流相關(guān)的功能，Download是從服務(wù)器下載數(shù)據(jù)操作，而Upload則是上傳數(shù)據(jù)到服務(wù)器。

相關(guān)項(xiàng)目

WebAPIDataStreaming
WebAPIClient
POCOLibrary

在對(duì)代碼解釋之前，首先來了解如何配置IIS（7.5）和Web API 服務(wù)Web.Config 文件。

1. 保證Downloads/Uploads 涉及的文件具有讀寫權(quán)限。

2. 保證有足夠容量的內(nèi)容或因公安空間處理大文件。

3. 如果文件較大

a. 配置Web.Config 文件時(shí)，保證 maxRequestLength 時(shí)響應(yīng)時(shí)間 executionTimeout 合理。具體的值主要依賴于數(shù)據(jù)大小，允許一次性上傳的最大數(shù)據(jù)為2 GB

b. 保證 maxAllowedContentLength 在requestFiltering部分配置下正確設(shè)置，默認(rèn)值為30MB，最大值4GB

一旦完成預(yù)先配置，那么創(chuàng)建數(shù)據(jù)流服務(wù)就非常簡單了，首先需要定義文件流“ApiController”，如下：

1: /// <summary> 2: /// File streaming API 3: /// </summary> 4: [RoutePrefix("filestreaming")] 5: [RequestModelValidator] 6: public class StreamFilesController : ApiController 7: { 8: /// <summary> 9: /// Get File meta data 10: /// </summary> 11: /// <param name="fileName">FileName value</param> 12: /// <returns>FileMeta data response.</returns> 13: [Route("getfilemetadata")] 14: public HttpResponseMessage GetFileMetaData(string fileName) 15: { 16: // ......................................... 17: // Full code available in the source control 18: // ......................................... 19: ? 20: } 21: ? 22: /// <summary> 23: /// Search file and return its meta data in all download directories 24: /// </summary> 25: /// <param name="fileName">FileName value</param> 26: /// <returns>List of file meta datas response</returns> 27: [HttpGet] 28: [Route("searchfileindownloaddirectory")] 29: public HttpResponseMessage SearchFileInDownloadDirectory(string fileName) 30: { 31: // ......................................... 32: // Full code available in the source control 33: // ......................................... 34: } 35: ? 36: /// <summary> 37: /// Asynchronous Download file 38: /// </summary> 39: /// <param name="fileName">FileName value</param> 40: /// <returns>Tasked File stream response</returns> 41: [Route("downloadasync")] 42: [HttpGet] 43: public async Task<HttpResponseMessage> DownloadFileAsync(string fileName) 44: { 45: // ......................................... 46: // Full code available in the source control 47: // ......................................... 48: } 49: ? 50: /// <summary> 51: /// Download file 52: /// </summary> 53: /// <param name="fileName">FileName value</param> 54: /// <returns>File stream response</returns> 55: [Route("download")] 56: [HttpGet] 57: public HttpResponseMessage DownloadFile(string fileName) 58: { 59: // ......................................... 60: // Full code available in the source control 61: // ......................................... 62: } 63: ? 64: /// <summary> 65: /// Upload file(s) 66: /// </summary> 67: /// <param name="overWrite">An indicator to overwrite a file if it exist in the server</param> 68: /// <returns>Message response</returns> 69: [Route("upload")] 70: [HttpPost] 71: public HttpResponseMessage UploadFile(bool overWrite) 72: { 73: // ......................................... 74: // Full code available in the source control 75: // ......................................... 76: } 77: ? 78: /// <summary> 79: /// Asynchronous Upload file 80: /// </summary> 81: /// <param name="overWrite">An indicator to overwrite a file if it exist in the server</param> 82: /// <returns>Tasked Message response</returns> 83: [Route("uploadasync")] 84: [HttpPost] 85: public async Task<HttpResponseMessage> UploadFileAsync(bool overWrite) 86: { 87: // ......................................... 88: // Full code available in the source control 89: // ......................................... 90: } 91: }

Download 服務(wù)方法首先需要確認(rèn)請(qǐng)求的文件是否存在，如果未找到，則返回錯(cuò)誤提示“file is not found”,如果找到此文件，內(nèi)容則轉(zhuǎn)換為字節(jié)附加到響應(yīng)對(duì)象，為“application/octet-stream” MIMI 內(nèi)容類型。

1: /// <summary> 2: /// Download file 3: /// </summary> 4: /// <param name="fileName">FileName value<param> 5: /// <returns>File stream response<returns> 6: [Route("download")] 7: [HttpGet] 8: public HttpResponseMessage DownloadFile(string fileName) 9: { 10: HttpResponseMessage response = Request.CreateResponse(); 11: FileMetaData metaData = new FileMetaData(); 12: try 13: { 14: string filePath = Path.Combine(this.GetDownloadPath(), @"\", fileName); 15: FileInfo fileInfo = new FileInfo(filePath); 16: ? 17: if (!fileInfo.Exists) 18: { 19: metaData.FileResponseMessage.IsExists = false; 20: metaData.FileResponseMessage.Content = string.Format("{0} file is not found !", fileName); 21: response = Request.CreateResponse(HttpStatusCode.NotFound, metaData, new MediaTypeHeaderValue("text/json")); 22: } 23: else 24: { 25: response.Headers.AcceptRanges.Add("bytes"); 26: response.StatusCode = HttpStatusCode.OK; 27: response.Content = new StreamContent(fileInfo.ReadStream()); 28: response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment"); 29: response.Content.Headers.ContentDisposition.FileName = fileName; 30: response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream"); 31: response.Content.Headers.ContentLength = fileInfo.Length; 32: } 33: } 34: catch (Exception exception) 35: { 36: // Log exception and return gracefully 37: metaData = new FileMetaData(); 38: metaData.FileResponseMessage.Content = ProcessException(exception); 39: response = Request.CreateResponse(HttpStatusCode.InternalServerError, metaData, new MediaTypeHeaderValue("text/json")); 40: } 41: return response; 42: }

Upload服務(wù)方法則會(huì)在multipart/form-data MIMI 內(nèi)容類型執(zhí)行，首先會(huì)檢測(cè)HTTP 請(qǐng)求的內(nèi)容類型是否是多主體，如果是，則對(duì)比內(nèi)容長度是否超過最大尺寸，如果沒有超過，則開始上傳內(nèi)容，當(dāng)操作完成之后，則提示相應(yīng)的信息。

代碼片段如下：

1: /// <summary> 2: /// Upload file(s) 3: /// </summary> 4: /// <param name="overWrite">An indicator to overwrite a file if it exist in the server.</param> 5: /// <returns>Message response</returns> 6: [Route("upload")] 7: [HttpPost] 8: public HttpResponseMessage UploadFile(bool overWrite) 9: { 10: HttpResponseMessage response = Request.CreateResponse(); 11: List<FileResponseMessage> fileResponseMessages = new List<FileResponseMessage>(); 12: FileResponseMessage fileResponseMessage = new FileResponseMessage { IsExists = false }; 13: ? 14: try 15: { 16: if (!Request.Content.IsMimeMultipartContent()) 17: { 18: fileResponseMessage.Content = "Upload data request is not valid !"; 19: fileResponseMessages.Add(fileResponseMessage); 20: response = Request.CreateResponse(HttpStatusCode.UnsupportedMediaType, fileResponseMessages, new MediaTypeHeaderValue("text/json")); 21: } 22: ? 23: else 24: { 25: response = ProcessUploadRequest(overWrite); 26: } 27: } 28: catch (Exception exception) 29: { 30: // Log exception and return gracefully 31: fileResponseMessage = new FileResponseMessage { IsExists = false }; 32: fileResponseMessage.Content = ProcessException(exception); 33: fileResponseMessages.Add(fileResponseMessage); 34: response = Request.CreateResponse(HttpStatusCode.InternalServerError, fileResponseMessages, new MediaTypeHeaderValue("text/json")); 35: ? 36: } 37: return response; 38: } 39: ? 40: /// <summary> 41: /// Asynchronous Upload file 42: /// </summary> 43: /// <param name="overWrite">An indicator to overwrite a file if it exist in the server.<param> 44: /// <returns>Tasked Message response</returns> 45: [Route("uploadasync")] 46: [HttpPost] 47: public async Task<HttpResponseMessage> UploadFileAsync(bool overWrite) 48: { 49: return await new TaskFactory().StartNew( 50: () => 51: { 52: return UploadFile(overWrite); 53: }); 54: } 55: ? 56: /// <summary> 57: /// Process upload request in the server 58: /// </summary> 59: /// <param name="overWrite">An indicator to overwrite a file if it exist in the server.</param> 60: /// </returns>List of message object</returns> 61: private HttpResponseMessage ProcessUploadRequest(bool overWrite) 62: { 63: // ......................................... 64: // Full code available in the source control 65: // ......................................... 66: }

調(diào)用download 及 upload 文件方法是控制臺(tái)應(yīng)用，App 假定文件流服務(wù)通過HttpClient和相關(guān)類。基本下載文件代碼，創(chuàng)建下載HTTP 請(qǐng)求對(duì)象。

1: /// <summary> 2: /// Download file 3: /// </summary> 4: /// <returns>Awaitable Task object</returns> 5: private static async Task DownloadFile() 6: { 7: Console.ForegroundColor = ConsoleColor.Green; 8: Console.WriteLine("Please specify file name with extension and Press Enter :- "); 9: string fileName = Console.ReadLine(); 10: string localDownloadPath = string.Concat(@"c:\", fileName); // the path can be configurable 11: bool overWrite = true; 12: string actionURL = string.Concat("downloadasync?fileName=", fileName); 13: ? 14: try 15: { 16: Console.WriteLine(string.Format("Start downloading @ {0}, {1} time ", 17: DateTime.Now.ToLongDateString(), 18: DateTime.Now.ToLongTimeString())); 19: ? 20: ? 21: using (HttpClient httpClient = new HttpClient()) 22: { 23: httpClient.BaseAddress = baseStreamingURL; 24: HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, actionURL); 25: ? 26: await httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead). 27: ContinueWith((response) 28: => 29: { 30: Console.WriteLine(); 31: try 32: { 33: ProcessDownloadResponse(localDownloadPath, overWrite, response); 34: } 35: catch (AggregateException aggregateException) 36: { 37: Console.ForegroundColor = ConsoleColor.Red; 38: Console.WriteLine(string.Format("Exception : ", aggregateException)); 39: } 40: }); 41: } 42: } 43: catch (Exception ex) 44: { 45: Console.ForegroundColor = ConsoleColor.Red; 46: Console.WriteLine(ex.Message); 47: } 48: } 49: ? 50: ? 51: /// <summary> 52: /// Process download response object 53: /// </summary> 54: /// <param name="localDownloadFilePath">Local download file path</param> 55: /// <param name="overWrite">An indicator to overwrite a file if it exist in the client.</param> 56: /// <param name="response">Awaitable HttpResponseMessage task value</param> 57: private static void ProcessDownloadResponse(string localDownloadFilePath, bool overWrite, 58: Task<HttpResponseMessage> response) 59: { 60: if (response.Result.IsSuccessStatusCode) 61: { 62: response.Result.Content.DownloadFile(localDownloadFilePath, overWrite). 63: ContinueWith((downloadmessage) 64: => 65: { 66: Console.ForegroundColor = ConsoleColor.Green; 67: Console.WriteLine(downloadmessage.TryResult()); 68: }); 69: } 70: else 71: { 72: ProcessFailResponse(response); 73: } 74: }

注意上述代碼中HttpClient 對(duì)象發(fā)送請(qǐng)求，并等待響應(yīng)發(fā)送Header內(nèi)容（HttpCompletionOption.ResponseHeadersRead ）。而不是發(fā)送全部的響應(yīng)內(nèi)容文件。一旦Response header 被讀，則執(zhí)行驗(yàn)證，一旦驗(yàn)證成功，則執(zhí)行下載方法。

以下代碼調(diào)用upload 文件流，與下載方法類似，創(chuàng)建多主體表單數(shù)據(jù)，并發(fā)送給服務(wù)器端。

1: /// <summary> 2: /// Upload file 3: /// </summary> 4: /// <returns>Awaitable task object</returns> 5: private static async Task UploadFile() 6: { 7: try 8: { 9: string uploadRequestURI = "uploadasync?overWrite=true"; 10: ? 11: MultipartFormDataContent formDataContent = new MultipartFormDataContent(); 12: ? 13: // Validate the file and add to MultipartFormDataContent object 14: formDataContent.AddUploadFile(@"c:\nophoto.png"); 15: formDataContent.AddUploadFile(@"c:\ReadMe.txt"); 16: ? 17: if (!formDataContent.HasContent()) // No files found to be uploaded 18: { 19: Console.ForegroundColor = ConsoleColor.Red; 20: Console.Write(formDataContent.GetUploadFileErrorMesage()); 21: return; 22: } 23: else 24: { 25: string uploadErrorMessage = formDataContent.GetUploadFileErrorMesage(); 26: if (!string.IsNullOrWhiteSpace(uploadErrorMessage)) // Some files couldn't be found 27: { 28: Console.ForegroundColor = ConsoleColor.Red; 29: Console.Write(uploadErrorMessage); 30: } 31: ? 32: HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, uploadRequestURI); 33: request.Content = formDataContent; 34: ? 35: using (HttpClient httpClient = new HttpClient()) 36: { 37: Console.ForegroundColor = ConsoleColor.Green; 38: Console.WriteLine(string.Format("Start uploading @ {0}, {1} time ", 39: DateTime.Now.ToLongDateString(), 40: DateTime.Now.ToLongTimeString())); 41: ? 42: httpClient.BaseAddress = baseStreamingURL; 43: await httpClient.SendAsync(request). 44: ContinueWith((response) 45: => 46: { 47: try 48: { 49: ProcessUploadResponse(response); 50: } 51: catch (AggregateException aggregateException) 52: { 53: Console.ForegroundColor = ConsoleColor.Red; 54: Console.WriteLine(string.Format("Exception : ", aggregateException)); 55: } 56: }); 57: } 58: } 59: } 60: catch (Exception ex) 61: { 62: Console.ForegroundColor = ConsoleColor.Red; 63: Console.WriteLine(ex.Message); 64: } 65: } 66: ? 67: /// <summary> 68: /// Process download response object 69: /// </summary> 70: /// <param name="response">Awaitable HttpResponseMessage task value</param> 71: private static void ProcessUploadResponse(Task<HttpResponseMessage> response) 72: { 73: if (response.Result.IsSuccessStatusCode) 74: { 75: string uploadMessage = string.Format("\nUpload completed @ {0}, {1} time ", 76: DateTime.Now.ToLongDateString(), 77: DateTime.Now.ToLongTimeString()); 78: Console.ForegroundColor = ConsoleColor.Green; 79: Console.WriteLine(string.Format("{0}\nUpload Message : \n{1}", uploadMessage, 80: JsonConvert.SerializeObject(response.Result.Content.ReadAsAsync<List<FileResponseMessage>>().TryResult(), Formatting.Indented))); 81: } 82: else 83: { 84: ProcessFailResponse(response); 85: } 86: }

數(shù)據(jù)流項(xiàng)目由可擴(kuò)展類和方法組成，本文就不再詳述。下篇文章中將介紹“使用HTTPS 開發(fā)項(xiàng)目”

數(shù)據(jù)流是數(shù)據(jù)傳輸中的重要部分，學(xué)習(xí)了本節(jié)內(nèi)容有助于大家更好地進(jìn)行ASP.NET的開發(fā)。當(dāng)然，還可以借助一些開發(fā)工具來助力開發(fā)過程。ComponentOne Studio for ASP.NET?提供了一整套完備的開發(fā)工具包，用于在各種瀏覽器中創(chuàng)建和設(shè)計(jì)具有現(xiàn)代風(fēng)格的Web應(yīng)用程序。

下載源代碼

原文鏈接：http://www.codeproject.com/Articles/838274/Web-API-Thoughts-of-Data-Streaming#Hist

原文鏈接：http://www.cnblogs.com/powertoolsteam/p/5029475.html

轉(zhuǎn)載于:https://www.cnblogs.com/Percy_Lee/p/5662424.html

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