Question

我一直在研究一个项目，该项目通过httprequests从其余服务器获取结果。在这种情况下，我尝试并成功（昨天，相同的代码也起作用。）搜索国家/地区，并将其标志设置为dipslay。

我已经缩小了功能“ makeRequest”正在挂断我的程序。

挂断电话是指我什至无法通过单击右上角的“ x”来关闭表单，而不得不通过单击“停止调试”来强制退出。

任何暗示我做错了或出错的事情将不胜感激。

表单使用的代码：

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

namespace ApiQueryHandler
{
abstract class QueryCreator
{

    static public string createQueryLandcode(String country)
    {
        string queryStandaard = "https://restcountries.eu/rest/v2/name/";
        string queryLandCode = "?fields=alpha2Code";
        string query = queryStandaard + country + queryLandCode;
        return query;
    }
    static public string makeRequest(string query)
    {
        WebRequest request = WebRequest.Create(query);
        request.Credentials = CredentialCache.DefaultCredentials;
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        Stream dataStream = response.GetResponseStream();
        StreamReader reader = new StreamReader(dataStream);
        string responseFromServer = reader.ReadToEnd();
        reader.Close();
        dataStream.Close();
        response.Close();
        return responseFromServer;
    }
    static public string createQueryFlag(string country)
    {
        string queryStandaard = "https://restcountries.eu/rest/v2/name/";
        string queryFlag = "?fields=flag";
        string query = queryStandaard + country + queryFlag;
        return query;
    }
    static public string getSVGFlagUrl(string queryResponseFlag)
    {
        String beginUrl = queryResponseFlag.Substring(10);
        int endUrl = beginUrl.IndexOf('"');
        String url = queryResponseFlag.Substring(10,endUrl);
        return url;
    }
    static public string getPNGFlagUrl(string landCode)
    {
        string PNGUrl = "https://www.countryflags.io/"+landCode+"/flat/64.png";
        return PNGUrl;
    }
    static public string getCode(string queryResponseCode)
    {
        String beginCode = queryResponseCode.Substring(16);
        int endCode = beginCode.IndexOf('"');
        String code = queryResponseCode.Substring(16, endCode);
        return code;
    }
    static public string getCodeShort(string queryResponseCode)
    {
        String beginCode = queryResponseCode.Substring(10);
        int endCode = beginCode.IndexOf('"');
        String code = queryResponseCode.Substring(10, endCode-1);
        return code;
    }
}

}

表单代码：

private void textBoxCounrty_TextChanged(object sender, EventArgs e)
    {
        string country = textBoxCountry.Text;
        string queryLandcode = QueryCreator.createQueryLandcode(country);
        string queryFlag = QueryCreator.createQueryFlag(country);
        try
        {

            string responseLandcode = QueryCreator.makeRequest(queryLandcode);
            string responseFlag = QueryCreator.makeRequest(queryFlag);
            string SVGUrl = QueryCreator.getSVGFlagUrl(responseFlag);
            labelURLQuery.Text = queryLandcode;
            string processedLandcode = QueryCreator.getCode(responseLandcode);
            string PNGUrl = QueryCreator.getPNGFlagUrl(processedLandcode);
            richTextBoxServerResponse.Text = responseLandcode+"\n\n"+processedLandcode+"\n\n"+PNGUrl+"\n\n"+SVGUrl;
            pictureBoxFlag.Load(PNGUrl);
            labelERROR.Text = "";
        }
        catch (WebException)
        {
            labelERROR.Text = "404 not found";
        }
        catch (ArgumentException)
        {
            labelERROR.Text = "404 not found";
        }

    }

Answer 1

使您的请求异步

public async Task<string> makerequest(string query){

}

然后在调用它时使用await修饰符

string response= await makerequest(yourstring)

异步执行此操作可以停止挂起的问题。重要的是要注意，您不必使调用方法与之异步，因为异步调用只能由异步方法进行。

Answer 2

似乎https://restcountries.eu（我向其发送请求的其余服务器没有响应）

在使用其他http://countryapi.gear.host之类的其他服务器时，我的代码（原始）确实有效。

request.GetResponse（）似乎挂断了我的程序

2 个答案: