相关疑难解决方法(0)

我正在尝试根据我调用的API 设置对象的Content-Type标头HttpClient.

我尝试过Content-Type如下设置:

using (var httpClient = new HttpClient())
{
    httpClient.BaseAddress = new Uri("http://example.com/");
    httpClient.DefaultRequestHeaders.Add("Accept", "application/json");
    httpClient.DefaultRequestHeaders.Add("Content-Type", "application/json");
    // ...
}

它允许我添加Accept标题但是当我尝试添加Content-Type它时抛出以下异常:

未使用的标题名称.确保请求标头与对象HttpRequestMessage一起使用 ,响应标头HttpResponseMessage和带有HttpContent对象的内容标头.

如何Content-Type在HttpClient请求中设置标头？

.NET Framework 4.5中的System.Net.Http.HttpClient和System.Net.Http.HttpClientHandler实现了IDisposable(通过System.Net.Http.HttpMessageInvoker).

该using声明文件说:

通常,当您使用IDisposable对象时,您应该在using语句中声明并实例化它.

这个答案使用了这种模式:

var baseAddress = new Uri("http://example.com");
var cookieContainer = new CookieContainer();
using (var handler = new HttpClientHandler() { CookieContainer = cookieContainer })
using (var client = new HttpClient(handler) { BaseAddress = baseAddress })
{
    var content = new FormUrlEncodedContent(new[]
    {
        new KeyValuePair<string, string>("foo", "bar"),
        new KeyValuePair<string, string>("baz", "bazinga"),
    });
    cookieContainer.Add(baseAddress, new Cookie("CookieName", "cookie_value"));
    var result = client.PostAsync("/test", content).Result;
    result.EnsureSuccessStatusCode();
}

但是微软最明显的例子并没有Dispose()明确地或隐含地调用.例如:

• 在原来的博客文章中宣布的HttpClient的RELASE. …

我想问你关于正确架构何时使用的意见Task.Run.我在WPF .NET 4.5应用程序(使用Caliburn Micro框架)中遇到了滞后的UI.

基本上我在做(非常简化的代码片段):

public class PageViewModel : IHandle<SomeMessage>
{
   ...

   public async void Handle(SomeMessage message)
   {
      ShowLoadingAnimation();

      // Makes UI very laggy, but still not dead
      await this.contentLoader.LoadContentAsync();

      HideLoadingAnimation();
   }
}

public class ContentLoader
{
    public async Task LoadContentAsync()
    {
        await DoCpuBoundWorkAsync();
        await DoIoBoundWorkAsync();
        await DoCpuBoundWorkAsync();

        // I am not really sure what all I can consider as CPU bound as slowing down the UI
        await DoSomeOtherWorkAsync();
    }
}

从我阅读/看到的文章/视频中,我知道await async不一定在后台线程上运行,并且需要在后台开始工作,需要等待它Task.Run(async () => …