如何在ASP.NET MVC中通过HTML文本框设置C#控制器字符串变量

按以下步骤修改代码，即可实现需求：

1. 解决控制器配置持久化问题 #

ASP.NET Core的控制器是瞬时对象，每次请求都会创建新实例，直接用控制器字段存储machineIP会导致每次请求重置为默认值。需要创建单例服务来保存配置：

创建MachineConfigService.cs服务类：

namespace MachineManager.Services
{
    public class MachineConfigService
    {
        public string MachineIP { get; set; } = "192.168.10.107";
        public string Url { get; set; } = "https://192.168.10.107/selfcashapi";
    }
}

在Program.cs注册为单例：

builder.Services.AddSingleton<MachineConfigService>();

2. 修改控制器逻辑，注入配置服务 #

更新VNEcontroller.cs，替换原有字段为注入的配置服务，确保IP和URL在请求间保持一致：

using MachineManager.Models;
using MachineManager.Services;
using Microsoft.AspNetCore.Mvc;
using System.Net;
using System.IO;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace MachineManager.Controllers
{
    [ApiController]
    [Route("api/[controller]")]
    public class VNEcontroller : Controller
    {
        private readonly MachineConfigService _configService;

        // 注入配置服务
        public VNEcontroller(MachineConfigService configService)
        {
            _configService = configService;
        }

        [HttpPost("SetIP")]
        public IActionResult SetIP([FromForm] string VNEIP)
        {
            if (!string.IsNullOrEmpty(VNEIP))
            {
                _configService.MachineIP = VNEIP;
                _configService.Url = $"https://{VNEIP}/selfcashapi/";
            }
            return Ok(new VNEViewModel 
            { 
                machineIP = _configService.MachineIP, 
                url = _configService.Url 
            });
        }

        [HttpPost("Login")]
        public IActionResult Login()
        {
            var httpWebRequest = (HttpWebRequest)WebRequest.Create(_configService.Url);
            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Method = "POST";
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
            ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

            using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            {
                object jsonObj = new { tipo = 40 };
                string json = JsonConvert.SerializeObject(jsonObj);
                streamWriter.Write(json);
            }

            string result = "";
            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                result = streamReader.ReadToEnd();
            }

            JObject jObject = JObject.Parse(result);
            string req_status = jObject["req_status"]?.ToString();
            return Ok(req_status);
        }

        // EmptyHopper方法同样替换为使用配置服务的Url
        [HttpPost("EmptyHopper")]
        public IActionResult EmptyHopper(bool totalEmpty = true)
        {
            var httpWebRequest = (HttpWebRequest)WebRequest.Create(_configService.Url);
            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Method = "POST";
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
            ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

            using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            {
                object jsonObj = new { tipo = 50, full = totalEmpty ? 0 : 1 };
                string json = JsonConvert.SerializeObject(jsonObj);
                streamWriter.Write(json);
            }

            string result = "";
            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                result = streamReader.ReadToEnd();
            }
            return Ok(result);
        }
    }
}

3. 前端视图添加交互逻辑 #

更新JCash.cshtml，补充JavaScript函数实现“先更新IP再登录”的流程：

@page
@using MachineManager.Controllers
@model VNEViewModel
@{ 
    ViewData["Title"] = "VNE JCash Manager";
}

<html>
<head>
    <title>JCash Manager</title>
</head>
<body>
    <div>
        <input id="IPlabel" name="VNEIP" type="text" placeholder="IP da Máquina" />
        <button id="callLogin" type="button" onclick="Login()">Conectar</button>
    </div>

    <script>
        async function Login() {
            const ip = document.getElementById('IPlabel').value.trim();
            if (!ip) {
                alert('Por favor, insira o IP da máquina!');
                return;
            }

            try {
                // 第一步：把IP传给后端更新配置
                await fetch('/api/VNE/SetIP', {
                    method: 'POST',
                    headers: {
                        'Content-Type': 'application/x-www-form-urlencoded',
                    },
                    body: `VNEIP=${encodeURIComponent(ip)}`
                });

                // 第二步：执行登录请求
                const response = await fetch('/api/VNE/Login', {
                    method: 'POST',
                    headers: {
                        'Content-Type': 'application/json',
                    }
                });

                const result = await response.text();
                console.log('Resultado do Login:', result);
                alert('Conectado com sucesso! Resultado: ' + result);
            } catch (error) {
                console.error('Erro:', error);
                alert('Ocorreu um erro ao conectar!');
            }
        }
    </script>
</body>
</html>

核心说明 #

• 单例服务MachineConfigService负责持久化IP和URL，避免控制器每次请求重置配置。
• 前端通过异步请求分两步操作：先更新IP配置，再执行登录，保证登录时使用最新输入的IP。
• 移除了原表单的跳转逻辑，改用Fetch API实现无刷新交互，更符合现代Web应用的体验。

内容的提问来源于stack exchange，提问作者Guilherme Silvestre