WebAPI-HTTP編程模型

帶著問題去思考，大家好！
它是什麼？它包含什麼？它能幹什麼？

消息

HTTP編程模型的核心就是消息抽象，表示為：HttPRequestMessage,HttpResponseMessage.用於客戶端和服務端之間交換請求和響應消息。

HttpMethod類包含了一組靜態屬性：

   private static readonly HttpMethod getMethod = new HttpMethod("GET");

        private static readonly HttpMethod putMethod = new HttpMethod("PUT");

        private static readonly HttpMethod postMethod = new HttpMethod("POST");

        private static readonly HttpMethod deleteMethod = new HttpMethod("DELETE");

        private static readonly HttpMethod headMethod = new HttpMethod("HEAD");

        private static readonly HttpMethod optionsMethod = new HttpMethod("OPTIONS");

        private static readonly HttpMethod traceMethod = new HttpMethod("TRACE")

標頭

• HttpRequestHeaders：包含請求標頭
• HttpResponseHeaders：包含響應標頭
• HttpContentHeaders：包含內容標頭

消息內容

HttpContent包含了非虛擬公共方法

• Task<string> ReadAsStringAsync()
• Task<byte[]> ReadAsByteArrayAsync()
• Task<Stream> ReadAsStreamAsync()
• Task CopyToAsync(Stream stream, TransportContext context)

第一種方式用於推送方式訪問原始的消息內容。將一個流傳遞給CopyAsync方法，然後把消息內容推送到這個流中

using(car client=new HtppClient())
{
    var response=
          await client.GetAsync("",HttpCompletionOption.ResponseHeadersRead);
response.EnsureSuccessStatusCode();
var ms=new MemorySteam();
await response.Content.CopyToAsync(ms);
Assert.True(ms.Length>0);
}

也可以使用ReadAsStreamAsync().拉取方式訪問。這個方法非同步返回一個流

            using(var client=new HttpClient())
            {
                var response = await client.GetAsync("");
                response.EnsureSuccessStatusCode();
                var steam = await response.Content.ReadAsStreamAsync();
                var buffer = new byte[2 * 1024];
                var len = await steam.ReadAsync(buffer, 0, buffer.Length);
               
            }

ReadAsStringAsync和ReadAsByteArrayAsync-非同步提供消息內容的緩衝副本。ReadAsStringAsync返回原始的位元組內容，ReadAsByteArrayAsync將內容解碼為字元串返回

當然也可以擴展為

public override Task<object> ReadContentAsync(HttpRequestMessage request, IEnumerable<MediaTypeFormatter> formatters, IFormatterLogger formatterLogger)