C# 写一个Http 服务器和客户端

C# WinForm 程序中实现一个简易的 HTTP 服务器，能够处理 JSON 格式的 GET 和 POST 请求，这是一个很实用的需求，尤其适合做本地调试或轻量级服务。

实现思路

我会基于.NET自带的HttpListener类来实现这个 HTTP 服务器，它可以让 WinForm 程序监听指定端口并处理 HTTP 请求。核心步骤包括：

1. 1、初始化HttpListener并配置监听地址

2. 2、异步监听并处理客户端请求

3. 3、区分 GET/POST 请求类型

4. 4、解析 / 响应 JSON 格式数据

5. 5、在 WinForm 界面中控制服务器的启动和停止

完整代码实现

以下是一个开箱即用的 WinForm 程序代码，包含 UI 交互和完整的 HTTP 服务逻辑：

1. 首先是 Form1 的设计（Form1.Designer.cs 核心部分）

using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace HttpServerWinFormClient
{
    public partial class Form1 : Form
    {
        private readonly HttpClient _httpClient;
        // 默认服务器地址
        private string _baseUrl = "http://localhost:8080/";
        public Form1()
        {
            InitializeComponent();
            // 初始化HttpClient（设置超时10秒）
            _httpClient = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };

            // 初始化界面
            txtServerUrl.Text = _baseUrl;
            cbxMethod.SelectedIndex = 0; // 默认GET
            // 预设JSON模板
            txtRequestJson.Text = @"
{
    ""Id"": 1001,
    ""Name"": ""张三-测试中文"",
    ""Email"": ""zhangsan@test.com""
}";
            // 清空响应区
            ClearResponse();
        }
        #region 界面事件
        /// <summary>
        /// 发送请求按钮点击
        /// </summary>
        private async void btnSend_Click(object sender, EventArgs e)
        {
            try
            {
                // 禁用按钮，防止重复点击
                btnSend.Enabled = false;
                ClearResponse();
                _baseUrl = txtServerUrl.Text.Trim();
                if (string.IsNullOrWhiteSpace(_baseUrl))
                {
                    AppendLog("错误：服务器地址不能为空！", LogLevel.Error);
                    btnSend.Enabled = true;
                    return;
                }
                // 记录开始时间
                var stopwatch = System.Diagnostics.Stopwatch.StartNew();
                AppendLog($"开始发送{cbxMethod.Text}请求到：{_baseUrl}", LogLevel.Info);
                HttpResponseMessage response = null;
                if (cbxMethod.Text == "GET")
                {
                    // 发送GET请求
                    response = await _httpClient.GetAsync(_baseUrl);
                }
                else if (cbxMethod.Text == "POST")
                {
                    // 验证POST请求体
                    string json = txtRequestJson.Text.Trim();
                    if (string.IsNullOrWhiteSpace(json))
                    {
                        AppendLog("错误：POST请求体不能为空！", LogLevel.Error);
                        btnSend.Enabled = true;
                        return;
                    }
                    // 构造POST内容（UTF-8编码）
                    var content = new StringContent(json, Encoding.UTF8, "application/json");
                    content.Headers.TryAddWithoutValidation("Content-Type", "application/json; charset=utf-8");
                    // 发送POST请求
                    response = await _httpClient.PostAsync(_baseUrl, content);
                }
                // 停止计时
                stopwatch.Stop();
                // 解析响应
                string responseContent = await response.Content.ReadAsStringAsync();
                // 显示响应信息
                lblStatusCode.Text = $"状态码：{(int)response.StatusCode} ({response.StatusCode})";
                lblTimeCost.Text = $"耗时：{stopwatch.ElapsedMilliseconds} ms";
                txtResponseJson.Text = FormatJson(responseContent);
                // 记录日志
                AppendLog($"请求完成 - 状态码：{(int)response.StatusCode}，耗时：{stopwatch.ElapsedMilliseconds}ms", LogLevel.Success);
            }
            catch (HttpRequestException ex)
            {
                AppendLog($"请求异常：{ex.Message}（请检查服务器是否启动/地址是否正确）", LogLevel.Error);
            }
            catch (TaskCanceledException)
            {
                AppendLog("请求超时：服务器无响应（超时10秒）", LogLevel.Error);
            }
            catch (Exception ex)
            {
                AppendLog($"未知异常：{ex.Message}", LogLevel.Error);
            }
            finally
            {
                btnSend.Enabled = true;
            }
        }
        /// <summary>
        /// 清空响应按钮
        /// </summary>
        private void btnClear_Click(object sender, EventArgs e)
        {
            ClearResponse();
            txtLog.Clear();
        }
        /// <summary>
        /// 快速测试：正常POST（含中文）
        /// </summary>
        private void btnTestNormalPost_Click(object sender, EventArgs e)
        {
            cbxMethod.SelectedIndex = 1; // 切换到POST
            txtRequestJson.Text = @"
{
    ""Id"": 1001,
    ""Name"": ""张三-测试中文"",
    ""Email"": ""zhangsan@test.com""
}";
            AppendLog("已加载【正常POST（含中文）】测试模板", LogLevel.Info);
        }
        /// <summary>
        /// 快速测试：错误JSON（Id为字符串）
        /// </summary>
        private void btnTestErrorPost_Click(object sender, EventArgs e)
        {
            cbxMethod.SelectedIndex = 1; // 切换到POST
            txtRequestJson.Text = @"
{
    ""Id"": ""1001a"",
    ""Name"": ""李四"",
    ""Email"": ""lisi@test.com""
}";
            AppendLog("已加载【错误JSON（Id为字符串）】测试模板", LogLevel.Info);
        }
        /// <summary>
        /// 请求方法切换（隐藏/显示POST请求体）
        /// </summary>
        private void cbxMethod_SelectedIndexChanged(object sender, EventArgs e)
        {
            // GET隐藏请求体，POST显示
            panelPostJson.Visible = (cbxMethod.Text == "POST");
        }
        #endregion
        #region 辅助方法
        /// <summary>
        /// 清空响应区域
        /// </summary>
        private void ClearResponse()
        {
            lblStatusCode.Text = "状态码：-";
            lblTimeCost.Text = "耗时：- ms";
            txtResponseJson.Clear();
        }
        /// <summary>
        /// 格式化JSON字符串（便于阅读）
        /// </summary>
        private string FormatJson(string json)
        {
            if (string.IsNullOrWhiteSpace(json)) return "";
            try
            {
                // 使用Newtonsoft.Json格式化（需安装NuGet包）
                dynamic parsedJson = Newtonsoft.Json.JsonConvert.DeserializeObject(json);
                return Newtonsoft.Json.JsonConvert.SerializeObject(parsedJson, Newtonsoft.Json.Formatting.Indented);
            }
            catch
            {
                // 格式化失败则返回原字符串
                return json;
            }
        }
        /// <summary>
        /// 日志级别枚举
        /// </summary>
        private enum LogLevel
        {
            Info,
            Success,
            Error
        }
        /// <summary>
        /// 追加日志（线程安全）
        /// </summary>
        private void AppendLog(string message, LogLevel level = LogLevel.Info)
        {
            if (txtLog.InvokeRequired)
            {
                txtLog.Invoke(new Action<string, LogLevel>(AppendLog), message, level);
                return;
            }
            string timeStr = $"[{DateTime.Now:HH:mm:ss.fff}]";
            string levelStr = level switch
            {
                LogLevel.Info => "[信息]",
                LogLevel.Success => "[成功]",
                LogLevel.Error => "[错误]",
                _ => "[未知]"
            };
            string logLine = $"{timeStr} {levelStr} {message}{Environment.NewLine}";
            txtLog.AppendText(logLine);
            // 自动滚动到最后一行
            txtLog.SelectionStart = txtLog.TextLength;
            txtLog.ScrollToCaret();
        }
        #endregion
        #region 窗体设计器代码（自动生成）
        private System.ComponentModel.IContainer components = null;
        private TextBox txtServerUrl;
        private Label label1;
        private ComboBox cbxMethod;
        private Button btnSend;
        private Panel panelPostJson;
        private Label label2;
        private TextBox txtRequestJson;
        private Label label3;
        private TextBox txtResponseJson;
        private Label lblStatusCode;
        private Label lblTimeCost;
        private Button btnClear;
        private GroupBox groupBox1;
        private GroupBox groupBox2;
        private GroupBox groupBox3;
        private TextBox txtLog;
        private Button btnTestNormalPost;
        private Button btnTestErrorPost;
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            _httpClient?.Dispose();
            base.Dispose(disposing);
        }
        private void InitializeComponent()
        {
            this.txtServerUrl = new System.Windows.Forms.TextBox();
            this.label1 = new System.Windows.Forms.Label();
            this.cbxMethod = new System.Windows.Forms.ComboBox();
            this.btnSend = new System.Windows.Forms.Button();
            this.panelPostJson = new System.Windows.Forms.Panel();
            this.txtRequestJson = new System.Windows.Forms.TextBox();
            this.label2 = new System.Windows.Forms.Label();
            this.label3 = new System.Windows.Forms.Label();
            this.txtResponseJson = new System.Windows.Forms.TextBox();
            this.lblStatusCode = new System.Windows.Forms.Label();
            this.lblTimeCost = new System.Windows.Forms.Label();
            this.btnClear = new System.Windows.Forms.Button();
            this.groupBox1 = new System.Windows.Forms.GroupBox();
            this.btnTestErrorPost = new System.Windows.Forms.Button();
            this.btnTestNormalPost = new System.Windows.Forms.Button();
            this.groupBox2 = new System.Windows.Forms.GroupBox();
            this.groupBox3 = new System.Windows.Forms.GroupBox();
            this.txtLog = new System.Windows.Forms.TextBox();
            this.panelPostJson.SuspendLayout();
            this.groupBox1.SuspendLayout();
            this.groupBox2.SuspendLayout();
            this.groupBox3.SuspendLayout();
            this.SuspendLayout();
            // txtServerUrl
            this.txtServerUrl.Location = new System.Drawing.Point(85, 15);
            this.txtServerUrl.Name = "txtServerUrl";
            this.txtServerUrl.Size = new System.Drawing.Size(250, 23);
            this.txtServerUrl.TabIndex = 0;
            // label1
            this.label1.AutoSize = true;
            this.label1.Location = new System.Drawing.Point(10, 18);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(69, 17);
            this.label1.TabIndex = 1;
            this.label1.Text = "服务器地址：";
            // cbxMethod
            this.cbxMethod.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
            this.cbxMethod.Items.AddRange(new object[] { "GET", "POST" });
            this.cbxMethod.Location = new System.Drawing.Point(341, 15);
            this.cbxMethod.Name = "cbxMethod";
            this.cbxMethod.Size = new System.Drawing.Size(80, 25);
            this.cbxMethod.TabIndex = 2;
            this.cbxMethod.SelectedIndexChanged += new System.EventHandler(this.cbxMethod_SelectedIndexChanged);
            // btnSend
            this.btnSend.Location = new System.Drawing.Point(427, 15);
            this.btnSend.Name = "btnSend";
            this.btnSend.Size = new System.Drawing.Size(80, 25);
            this.btnSend.TabIndex = 3;
            this.btnSend.Text = "发送请求";
            this.btnSend.UseVisualStyleBackColor = true;
            this.btnSend.Click += new System.EventHandler(this.btnSend_Click);
            // panelPostJson
            this.panelPostJson.Controls.Add(this.txtRequestJson);
            this.panelPostJson.Controls.Add(this.label2);
            this.panelPostJson.Location = new System.Drawing.Point(10, 45);
            this.panelPostJson.Name = "panelPostJson";
            this.panelPostJson.Size = new System.Drawing.Size(497, 120);
            this.panelPostJson.TabIndex = 4;
            // txtRequestJson
            this.txtRequestJson.Dock = System.Windows.Forms.DockStyle.Fill;
            this.txtRequestJson.Multiline = true;
            this.txtRequestJson.Name = "txtRequestJson";
            this.txtRequestJson.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;
            this.txtRequestJson.Size = new System.Drawing.Size(497, 95);
            this.txtRequestJson.TabIndex = 1;
            // label2
            this.label2.AutoSize = true;
            this.label2.Location = new System.Drawing.Point(0, 0);
            this.label2.Name = "label2";
            this.label2.Size = new System.Drawing.Size(79, 17);
            this.label2.TabIndex = 0;
            this.label2.Text = "POST请求体：";
            // label3
            this.label3.AutoSize = true;
            this.label3.Location = new System.Drawing.Point(10, 170);
            this.label3.Name = "label3";
            this.label3.Size = new System.Drawing.Size(79, 17);
            this.label3.TabIndex = 5;
            this.label3.Text = "响应内容：";
            // txtResponseJson
            this.txtResponseJson.Location = new System.Drawing.Point(10, 190);
            this.txtResponseJson.Multiline = true;
            this.txtResponseJson.Name = "txtResponseJson";
            this.txtResponseJson.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;
            this.txtResponseJson.Size = new System.Drawing.Size(497, 120);
            this.txtResponseJson.TabIndex = 6;
            // lblStatusCode
            this.lblStatusCode.AutoSize = true;
            this.lblStatusCode.Location = new System.Drawing.Point(10, 315);
            this.lblStatusCode.Name = "lblStatusCode";
            this.lblStatusCode.Size = new System.Drawing.Size(53, 17);
            this.lblStatusCode.TabIndex = 7;
            this.lblStatusCode.Text = "状态码：-";
            // lblTimeCost
            this.lblTimeCost.AutoSize = true;
            this.lblTimeCost.Location = new System.Drawing.Point(120, 315);
            this.lblTimeCost.Name = "lblTimeCost";
            this.lblTimeCost.Size = new System.Drawing.Size(65, 17);
            this.lblTimeCost.TabIndex = 8;
            this.lblTimeCost.Text = "耗时：- ms";
            // btnClear
            this.btnClear.Location = new System.Drawing.Point(427, 310);
            this.btnClear.Name = "btnClear";
            this.btnClear.Size = new System.Drawing.Size(80, 25);
            this.btnClear.TabIndex = 9;
            this.btnClear.Text = "清空";
            this.btnClear.UseVisualStyleBackColor = true;
            this.btnClear.Click += new System.EventHandler(this.btnClear_Click);
            // groupBox1
            this.groupBox1.Controls.Add(this.btnTestErrorPost);
            this.groupBox1.Controls.Add(this.btnTestNormalPost);
            this.groupBox1.Controls.Add(this.txtServerUrl);
            this.groupBox1.Controls.Add(this.label1);
            this.groupBox1.Controls.Add(this.cbxMethod);
            this.groupBox1.Controls.Add(this.btnSend);
            this.groupBox1.Controls.Add(this.panelPostJson);
            this.groupBox1.Location = new System.Drawing.Point(10, 10);
            this.groupBox1.Name = "groupBox1";
            this.groupBox1.Size = new System.Drawing.Size(517, 180);
            this.groupBox1.TabIndex = 10;
            this.groupBox1.TabStop = false;
            this.groupBox1.Text = "请求配置";
            // btnTestNormalPost
            this.btnTestNormalPost.Location = new System.Drawing.Point(10, 170);
            this.btnTestNormalPost.Name = "btnTestNormalPost";
            this.btnTestNormalPost.Size = new System.Drawing.Size(150, 25);
            this.btnTestNormalPost.TabIndex = 5;
            this.btnTestNormalPost.Text = "快速测试：正常POST（中文）";
            this.btnTestNormalPost.UseVisualStyleBackColor = true;
            this.btnTestNormalPost.Click += new System.EventHandler(this.btnTestNormalPost_Click);
            // btnTestErrorPost
            this.btnTestErrorPost.Location = new System.Drawing.Point(166, 170);
            this.btnTestErrorPost.Name = "btnTestErrorPost";
            this.btnTestErrorPost.Size = new System.Drawing.Size(150, 25);
            this.btnTestErrorPost.TabIndex = 6;
            this.btnTestErrorPost.Text = "快速测试：错误JSON（Id字符串）";
            this.btnTestErrorPost.UseVisualStyleBackColor = true;
            this.btnTestErrorPost.Click += new System.EventHandler(this.btnTestErrorPost_Click);
            // groupBox2
            this.groupBox2.Controls.Add(this.label3);
            this.groupBox2.Controls.Add(this.txtResponseJson);
            this.groupBox2.Controls.Add(this.lblStatusCode);
            this.groupBox2.Controls.Add(this.lblTimeCost);
            this.groupBox2.Controls.Add(this.btnClear);
            this.groupBox2.Location = new System.Drawing.Point(10, 195);
            this.groupBox2.Name = "groupBox2";
            this.groupBox2.Size = new System.Drawing.Size(517, 340);
            this.groupBox2.TabIndex = 11;
            this.groupBox2.TabStop = false;
            this.groupBox2.Text = "响应结果";
            // groupBox3
            this.groupBox3.Controls.Add(this.txtLog);
            this.groupBox3.Location = new System.Drawing.Point(10, 540);
            this.groupBox3.Name = "groupBox3";
            this.groupBox3.Size = new System.Drawing.Size(517, 150);
            this.groupBox3.TabIndex = 12;
            this.groupBox3.TabStop = false;
            this.groupBox3.Text = "操作日志";
            // txtLog
            this.txtLog.Dock = System.Windows.Forms.DockStyle.Fill;
            this.txtLog.Multiline = true;
            this.txtLog.Name = "txtLog";
            this.txtLog.ReadOnly = true;
            this.txtLog.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;
            this.txtLog.Size = new System.Drawing.Size(517, 125);
            this.txtLog.TabIndex = 0;
            // Form1
            this.AutoScaleDimensions = new System.Drawing.SizeF(7F, 17F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(539, 700);
            this.Controls.Add(this.groupBox3);
            this.Controls.Add(this.groupBox2);
            this.Controls.Add(this.groupBox1);
            this.Name = "Form1";
            this.Text = "HTTP服务器测试客户端";
            this.panelPostJson.ResumeLayout(false);
            this.panelPostJson.PerformLayout();
            this.groupBox1.ResumeLayout(false);
            this.groupBox1.PerformLayout();
            this.groupBox2.ResumeLayout(false);
            this.groupBox2.PerformLayout();
            this.groupBox3.ResumeLayout(false);
            this.groupBox3.PerformLayout();
            this.ResumeLayout(false);
        }
        #endregion
    }
}

APIPost软件测试：

关键代码解释

1. 1、HttpListener

   ：核心类，用于监听 HTTP 请求，支持多前缀、多请求处理

2. 2、多线程处理

   ：监听线程和请求处理线程分离，避免阻塞 UI 线程

3. 3、JSON 序列化 / 反序列化

   ：使用JavaScriptSerializer处理 JSON 数据（也可以替换为 Newtonsoft.Json，更推荐）

4. 4、跨线程 UI 更新

   ：通过Control.Invoke实现日志的跨线程输出，避免 WinForm 跨线程访问异常

5. 5、异常处理

   ：完善的异常捕获和错误响应，保证服务器稳定运行

总结

1. 1、该 WinForm 服务器基于HttpListener实现，能够稳定处理 JSON 格式的 GET/POST 请求，核心是异步监听 + 多线程处理请求，避免阻塞 UI。

2. 2、关键要点：需要管理员权限运行、正确处理跨线程 UI 更新、严格遵循 HTTP 响应规范（设置 Content-Type、关闭响应流）。