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：
privatestaticreadonly HttpMethod getMethod = new HttpMethod("GET"); privatestaticreadonly HttpMethod putMethod = new HttpMethod("PUT"); privatestaticreadonly HttpMethod postMethod = new HttpMethod("POST"); privatestaticreadonly HttpMethod deleteMethod = new HttpMethod("DELETE"); privatestaticreadonly HttpMethod headMethod = new HttpMethod("HEAD"); privatestaticreadonly HttpMethod optionsMethod = new HttpMethod("OPTIONS"); privatestaticreadonly 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 = newbyte[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)
