[英]Handling response values using HttpClient
我正在实现一项服务,该服务使 API 使用HttpClient
调用外部服务。 特别是其中一个调用并不总是返回与预期相同的答案。 实际上:
这是我的电话:
using (HttpClientHandler handler = new HttpClientHandler { Credentials = new NetworkCredential(key, "") })
using (HttpClient client = new HttpClient(handler))
{
client.Timeout = TimeSpan.FromMilliseconds(Timeout.Infinite);
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, url);
using (HttpResponseMessage response = await client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead))
{
using (Stream body = await response.Content.ReadAsStreamAsync())
{
using (StreamReader reader = new StreamReader(body))
{
string read = string.Empty;
while (!reader.EndOfStream)
{
read += reader.ReadLine();
}
return JsonObject.Parse(read);
}
}
}
这是方面响应体 object:
{
"id" : 15,
"key" : "API_KEY",
"status" : "successful",
"sandbox" : true,
"created_at" : "2013-10-27T13:41:00Z",
"finished_at" : "2013-10-27T13:41:13Z",
"source_file" : {"id":2,"name":"testfile.pdf","size":90571},
"target_files" : [{"id":3,"name":"testfile.pptx","size":15311}],
"target_format" : "png",
"credit_cost" : 1
}
其中status
参数是successful
的,而target_files
参数是一个array of objects
。
然而,有时,答案基本上回来说它还没有完成转换(这个 API 是一个文件转换服务),这种类型的主体:
{
"id" : 15,
"key" : "API_KEY",
"status" : "converting",
"sandbox" : true,
"created_at" : "2013-10-27T13:41:00Z",
"finished_at" : "2013-10-27T13:41:13Z",
"source_file" : {"id":2,"name":"testfile.pdf","size":90571},
"target_files" : [{}],
"target_format" : "png",
"credit_cost" : 0
}
其中status
参数正在converting
并且target_files
参数为空。
有一种方法可以管理调用以返回响应的 object 但仅在status
参数successfull
时才返回? 谢谢
一些 api 采用wait=1
参数或类似于等待的参数。 否则,您必须轮询(可能是不同的网址)。
详细信息应从您的 API 文档中获得。
按照建议,解决了轮询请求:(客户端在 scope 级别实例化)
for (int attempt = 0; attempt < maxAttempts; attempt++)
{
using (HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, url))
{
TimeSpan delay = default;
using (HttpResponseMessage response = await _client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead).ConfigureAwait(false))
{
if (response.IsSuccessStatusCode)
{
using (HttpContent content = response.Content)
{
string data = await content.ReadAsStringAsync().ConfigureAwait(false);
JsonValue value = JsonObject.Parse(data);
JsonValue status = value["status"] ?? string.Empty;
string statusString = status != null ? (string)status : string.Empty;
if (!string.IsNullOrEmpty(status) && statusString.Equals("successful", StringComparison.InvariantCultureIgnoreCase))
return value;
}
}
delay = response.Headers.RetryAfter?.Delta ?? TimeSpan.FromSeconds(3);
}
await Task.Delay(delay);
}
}
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