'System.Net.HttpWebRequest‘不包含'GetResponse’的定义

Question

我正在创建一个用于在Visual 2013中使用restful方法的方法，其框架为4.5。这是windows_phone_8 (目标电话操作系统8.0)应用程序。这是我的密码。

static string HttpGet(string url)
    {
        HttpWebRequest req = WebRequest.Create(url)
                             as HttpWebRequest;
        string result = null;
        using (HttpWebResponse resp = req.GetResponse()
                                      as HttpWebResponse)
        {
            StreamReader reader =
                new StreamReader(resp.GetResponseStream());
            result = reader.ReadToEnd();
        }
        return result;
    }

但是，我得到了一个构建错误，如下所示

'System.Net.HttpWebRequest‘不包含'GetResponse’的定义，也找不到接受'System.Net.HttpWebRequest‘类型的第一个参数的扩展方法'GetResponse’(您缺少使用指令还是程序集引用？)

我不知道为什么会发生这种情况，相同的代码在相同的环境中可以很好地工作在Windows_application上。

更新:我也尝试过使用客户端方法

 WebClient client = new WebClient();

            client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");

            Stream data = client.OpenRead("http://192.168.10.73:8087/cisms/mobilews/login/userNameCheck?userName=supervisor");
            StreamReader reader = new StreamReader(data);
            string s = reader.ReadToEnd();
            data.Close();
            reader.Close();

又有一系列错误..。

错误1 'System.Net.WebHeaderCollection‘不包含'Add’的定义，也没有扩展方法'Add‘可以找到'System.Net.WebHeaderCollection’类型的第一个参数(您是缺少使用指令还是程序集引用？) 错误2 'System.Net.WebClient‘不包含'OpenRead’的定义，也找不到接受'System.Net.WebClient‘类型的第一个参数的扩展方法'OpenRead’(您缺少使用指令还是程序集引用？) 错误3 'System.Net.HttpWebRequest‘不包含'GetResponse’的定义，也找不到接受'System.Net.HttpWebRequest‘类型的第一个参数的扩展方法'GetResponse’(您缺少使用指令还是程序集引用？)

更新2 :

我根据@Gavin的答案修改了代码如下。

static async void HttpGet(string url)
    {
        Uri uri = new Uri(url);
        string result = null;
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
        request.Method = "GET";
        using (var response = (HttpWebResponse)(await Task<WebResponse>.Factory.FromAsync(request.BeginGetResponse, request.EndGetResponse, null)))
        {
            StreamReader reader = new StreamReader(response.GetResponseStream());
            result = reader.ReadToEnd();
        }
    }

但是控件返回到调用事件，从下面的行开始。

using (var response = (HttpWebResponse)(await Task<WebResponse>.Factory.FromAsync(request.BeginGetResponse, request.EndGetResponse, null)))

如果能在这方面提供任何帮助，我们将不胜感激。

答案:

我修改了代码如下，它现在正在工作。

public async Task<string> httpRequest(string url)
        {
            Uri uri = new Uri(url);
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
            string received;

            using (var response = (HttpWebResponse)(await Task<WebResponse>.Factory.FromAsync(request.BeginGetResponse, request.EndGetResponse, null)))
            {
                using (var responseStream = response.GetResponseStream())
                {
                    using (var sr = new StreamReader(responseStream))
                    {

                        received = await sr.ReadToEndAsync();
                    }
                }
            }

            return received;
        }

呼叫部分如下..。

private async void Button_Click(object sender, RoutedEventArgs e)
        {
            string uriString = "http://192.168.10.73:8087/cisms/mobilews/login/userNameCheck?userName=supervisor";
            var response = await httpRequest(uriString);
        }

更新3:

我在处理职位申请时还有一个问题。下面给出了我尝试过的代码。

static string HttpPost(string url, string[] paramName, string[] paramVal)
        {
            HttpWebRequest req = WebRequest.Create(new Uri(url))
                                 as HttpWebRequest;
            req.Method = "POST";
            req.ContentType = "application/x-www-form-urlencoded";

            // Build a string with all the params, properly encoded.
            // We assume that the arrays paramName and paramVal are
            // of equal length:
            StringBuilder paramz = new StringBuilder();
            for (int i = 0; i < paramName.Length; i++)
            {
                paramz.Append(paramName[i]);
                paramz.Append("=");
                paramz.Append(HttpUtility.UrlEncode(paramVal[i]));
                paramz.Append("&");
            }

            // Encode the parameters as form data:
            byte[] formData =
                UTF8Encoding.UTF8.GetBytes(paramz.ToString());
            req.ContentLength = formData.Length;

            // Send the request:
            using (Stream post = req.GetRequestStream())
            {
                post.Write(formData, 0, formData.Length);
            }

            // Pick up the response:
            string result = null;
            using (HttpWebResponse resp = req.GetResponse()
                                          as HttpWebResponse)
            {
                StreamReader reader =
                    new StreamReader(resp.GetResponseStream());
                result = reader.ReadToEnd();
            }

            return result;
        }

此方法在Windows 8应用程序中有两个构建错误

错误1 'System.Net.HttpWebRequest‘不包含'GetRequestStream’的定义，也找不到接受'System.Net.HttpWebRequest‘类型的第一个参数的扩展方法'GetRequestStream’(您缺少使用指令还是程序集引用？) 错误2 'System.Net.HttpWebRequest‘不包含'GetResponse’的定义，也找不到接受'System.Net.HttpWebRequest‘类型的第一个参数的扩展方法'GetResponse’(您缺少使用指令还是程序集引用？)

谢谢塞巴斯蒂安

Answer 1

WP8支持.NET Framework4.5的子集。

您可以根据需要调整下面的代码变体：

WebRequest request = WebRequest.Create(url);
return Task.Factory.FromAsync(request.BeginGetResponse, result =>
{
    HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(result);
    ...
}

或

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
request.Method = "GET";
using (var response = (HttpWebResponse)(await Task<WebResponse>.Factory.FromAsync(request.BeginGetResponse, request.EndGetResponse, null)))
{
    ...
}