System.Net.WebException：'错误：ConnectFailure（连接被拒绝）'

Question

我在下面有这个页面，我想将带有 json 的数据发送到我的 PHP 页面，以将用户插入 MySQL 数据库。 但连接失败：“System.Net.WebException：'错误：ConnectFailure（连接被拒绝）'”我在 xaml 中的页面：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:d="http://xamarin.com/schemas/2014/forms/design"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d"
             x:Class="fullApp.MainPage">

    <StackLayout Margin="0,30,0,0" Padding="20">
        <Entry x:Name="user" Placeholder="UserName"></Entry>
        <Entry x:Name="pass" Placeholder="Password" ></Entry>
        <Entry x:Name="phone" Placeholder="Phone Number"></Entry>
        <Entry x:Name="gover" Placeholder="Governorate"></Entry>
        <Entry x:Name="city" Placeholder="City"></Entry>
        <Entry x:Name="street" Placeholder="Street"></Entry>
        <Button x:Name="rigister" Clicked="Rigister_Clicked"></Button>
    </StackLayout>

</ContentPage>

我的cs页面：

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace fullApp
{
    // Learn more about making custom code visible in the Xamarin.Forms previewer
    // by visiting https://aka.ms/xamarinforms-previewer
    [DesignTimeVisible(false)]
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            pass.IsPassword = true;
        }

        void Rigister_Clicked(object sender, EventArgs e)
        {

            PostJson("http://localhost:3308/test/API/rigister_user.php", new users
            {
                username = user.Text,
                password = pass.Text,
                PhoneNumber = phone.Text,
                Governorate = gover.Text,
                City = city.Text,
                Street = street.Text
            });
            void PostJson(string uri, users postParameters)
            {
                string postData = JsonConvert.SerializeObject(postParameters);
                byte[] bytes = Encoding.UTF8.GetBytes(postData);
                var httpWebRequest = (HttpWebRequest)WebRequest.Create(uri);
                httpWebRequest.Method = "POST";
                httpWebRequest.ContentLength = bytes.Length;
                httpWebRequest.ContentType = "text/xml";
                using (Stream requestStream = httpWebRequest.GetRequestStream())
                {
                    requestStream.Write(bytes, 0, bytes.Count());
                }
                var httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
                if (httpWebResponse.StatusCode != HttpStatusCode.OK)
                {
                    string message = String.Format("POST failed. Received HTTP {0}", httpWebResponse.StatusCode);
                    throw new ApplicationException(message);
                }

            }
        }

    }
        public class users
        {
            public string username { get; set; }
            public string password { get; set; }
            public string PhoneNumber { get; set; }
            public string Governorate { get; set; }
            public string City { get; set; }
            public string Street { get; set; }
        }
}

此行上的调试停止，我收到错误消息：“System.Net.WebException：'错误：ConnectFailure（连接被拒绝）'”：

using (Stream requestStream = httpWebRequest.GetRequestStream())

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Answer 1

您可以使用 HttpClient 并将其设为异步 function：

async Task<string> PostJson(string uri, users postParameters)
{
  string postData = JsonConvert.SerializeObject(postParameters);
  using (var client = new HttpClient());
  var response = await client.PostAsync(uri, new StringContent(postData));
  if (!response.IsSuccessStatusCode) 
  {
     string message = String.Format("POST failed. Received HTTP {0}", response.StatusCode);
     throw new ApplicationException(message);
  }
  return await response.Content.ReadAsStringAsync();
}

更新：

我知道这并不能解决 OP 的问题，但这只是一种更优雅的方式。