WebAPI-HTTP编程模型

带着问题去思考，大家好！
它是什么？它包含什么？它能干什么？

消息

HTTP编程模型的核心就是消息抽象，表示为：HttPRequestMessage,HttpResponseMessage.用于客户端和服务端之间交换请求和响应消息。

HttpMethod类包含了一组静态属性：

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")

标头

HttpRequestHeaders：包含请求标头
HttpResponseHeaders：包含响应标头
HttpContentHeaders：包含内容标头

消息内容

HttpContent包含了非虚拟公共方法

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

第一种方式用于推送方式访问原始的消息内容。将一个流传递给CopyAsync方法，然后把消息内容推送到这个流中

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().拉取方式访问。这个方法异步返回一个流

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-异步提供消息内容的缓冲副本。ReadAsStringAsync返回原始的字节内容，ReadAsByteArrayAsync将内容解码为字符串返回

当然也可以扩展为

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

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