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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,它工作正常。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 Create 的定义。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,不能接受我的创建:

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 "";

        }

    }
}
4

2 回答 2

3

在您的表单应用程序中,您的类名为WebRequest,因此编译器正在该类中寻找Create方法,而不是System.Net.WebRequest该类。为了解决这个问题,完全限定WebRequestSystem.Net 中的:

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

感谢 Amiram 澄清这不是我最初认为的模棱两可的名称冲突。

于 2012-11-07T17:53:58.093 回答
0

出现此问题是因为您的目标.net framework小于4.5,要解决此问题只需将 更改为target framework4.5然后project properties application tab重新构建项目。

于 2015-07-09T15:14:15.340 回答