相关疑难解决方法(0)

.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. …

HttpClientWebAPI客户端的生命周期应该是多少？为多个调用
设置一个实例是否更好HttpClient？

创建和处理HttpClient每个请求的开销是多少,如下面的示例所示(摘自http://www.asp.net/web-api/overview/web-api-clients/calling-a-web-api-from- a-net-client):

using (var client = new HttpClient())
{
    client.BaseAddress = new Uri("http://localhost:9000/");
    client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    // New code:
    HttpResponseMessage response = await client.GetAsync("api/products/1");
    if (response.IsSuccessStatusCode)
    {
        Product product = await response.Content.ReadAsAsync<Product>();
        Console.WriteLine("{0}\t${1}\t{2}", product.Name, product.Price, product.Category);
    }
}

我如何将其转换为HttpClient？我要做的是向Twitter api提交一条Tweet，并以Json的身份获得回复。HttpWebRequest工作正常，但我只想将其移植到HttpClient。我在第二个代码示例中进行了尝试，但实际上并没有发送或接收响应。

HttpWebRequest request = null;
WebResponse response = null;
string responseCode = String.Empty;
try
{
    string postBody = "status=" + EncodingUtils.UrlEncode(status);

    request = (HttpWebRequest)HttpWebRequest.Create(resource_url);        
    request.ServicePoint.Expect100Continue = true;
    request.UseDefaultCredentials = true;
    request.PreAuthenticate = true;
    request.Credentials = CredentialCache.DefaultCredentials;
    request.ServicePoint.ConnectionLimit = 1;
    request.Headers.Add("Authorization", authHeader);
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded";

    using (Stream stream = request.GetRequestStream())
    {
        using (StreamWriter writer = new StreamWriter(stream))
        {                       
            writer.Write(postBody);
        }
    }
    using (response = request.GetResponse())
    {
        response.ContentType = "application/json";
        responseCode = ((HttpWebResponse)response).StatusCode.ToString();
    }
}
catch (WebException ex) …