Question

我昨天运行了一个控制台应用程序来发送和接收Web请求和Web响应，它运行正常。今天我在我的表单应用程序上测试相同的方法，我得到错误WebRequest不包含创建定义。我所有的进口都是一样的。这有点奇怪，我不知道我做错了什么。这是我的控制台应用程序的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using HtmlAgilityPack;
using System.Net;
using System.IO;

namespace WebrequestCsharp
{
    class Program
    {
        static void Main(string[] args)
        {
            StreamWriter sw;
            sw = File.AppendText("c:\\Temp\\webresponse.txt");
            //Create a Web-Request to an URL
            HttpWebRequest HWR_Request = (HttpWebRequest)WebRequest.Create("http://www.hitta.se/ericsson/företag_och_personer");

            //Send Web-Request and receive a Web-Response
            HttpWebResponse HWR_Response = (HttpWebResponse)HWR_Request.GetResponse();

            //Translate data from the Web-Response to a string
            Stream S_DataStream = HWR_Response.GetResponseStream();
            StreamReader SR_DataStream = new StreamReader(S_DataStream, Encoding.UTF8);
            string s_ResponseString = SR_DataStream.ReadToEnd();
            S_DataStream.Close();
            sw.WriteLine(s_ResponseString);
            sw.Flush();
            sw.Close();

            HtmlDocument doc = new HtmlDocument();
            doc.Load("c:\\Temp\\webresponse.txt");
            Console.ReadKey();
        }


    }
}

这是我的表单应用程序无法接受我的创建：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using HtmlAgilityPack;
using System.Net;
using System.IO;

namespace PhoneFind
{
    class WebRequest
    {
        private String url { get; set; }
        private String searchEngine { get; set; }
        HttpWebRequest HWR_Request = (HttpWebRequest)WebRequest.Create("http://www.hitta.se/ericsson/företag_och_personer");
        public WebRequest(String url, String searchEngine)
        {
            this.url = url;
            this.searchEngine = searchEngine;
        }

        // sends a request to the search engine 
        public String sendRequest(String url, String searchEngine)
        {
            switch (searchEngine){
                case "hitta":
                    //Create a Web-Request to a URL

                    //Send Web-Request and receive a Web-Response
                    HttpWebResponse HWR_Response = (HttpWebResponse)HWR_Request.GetResponse();

                    //Translate data from the Web-Response to a string
                    Stream S_DataStream = HWR_Response.GetResponseStream();
                    StreamReader SR_DataStream = new StreamReader(S_DataStream, Encoding.UTF8);
                    string s_ResponseString = SR_DataStream.ReadToEnd();
                    S_DataStream.Close();
                    break;
            }
            return "";

        }

    }
}

Answer 1

在表单应用程序中，您的类名为WebRequest，因此编译器正在该类中查找Create方法，而不是System.Net.WebRequest类。要解决此问题，请完全限定System.Net中的WebRequest：

HttpWebRequest HWR_Request = (HttpWebRequest)System.Net.WebRequest.Create("http://www.hitta.se/ericsson/företag_och_personer");

感谢Amiram澄清这不是一个模糊的名称冲突，正如我原先认为的那样。

Answer 2

出现此问题是因为您定位.net framework小于4.5，要解决此问题，只需将target framework更改为4.5，然后再project properties application tab，然后重建项目。

WebRequest不包含Create的定义

2 个答案: