背景
WebAPI 插件热插拔是指在不重启应用程序的情况下，能够动态地加载、更新或卸载功能模块（即插件）的能力。这种设计模式在软件开发中非常有用，尤其是在需要频繁更新或扩展功能的大型系统中。通过实现插件架构，可以将系统的不同部分解耦，使得它们可以独立开发、测试和部署。
对于WebAPI来说，这意味着服务端可以在运行时根据业务需求灵活调整其提供的API接口和服务逻辑，而无需担心每次修改都要重新启动整个应用，从而减少停机时间，提高系统的稳定性和灵活性。
程序演示
我们启动程序通过调用动态接口使用插件的增删改查等功能；，其中带{DynamicParam}的是你要使用的插件的名称；{funName}是你要使用插件的接口名称。
程序运行界面
查询筛选接口
使用postman 进行查询筛选博客操作
插件新增接口
插件的新增博客接口，然后看数据库变化
插件更新接口
插件的更新博客接口
插件删除接口
插件上传文件接口
代码实现
前提准备
需要安装nuget程序包：Newtonsoft.Json，SqlSugarCore。方便我们做类型转换和数据存储的相关功能；
1，首先我们创建一个webapi 的项目，然后定义一个插件IPluginDllApi.cs的接口（后续新增的类库需要继承用）
using Microsoft.AspNetCore.Mvc; namespace DynamicPluginApiDemo.Utils { public interface IPluginDllApi { string Name { get; } IActionResult GetRequest(string funName, Dictionary<string, string> queryParameters); IActionResult PostRequestForm(string funName, Dictionary<string, string> queryParameters, IFormCollection formData); IActionResult PostRequestBody(string funName, Dictionary<string, string> queryParameters, object jsonData); } }
2，创建一个插件帮助类和数据库帮助类。
using SqlSugar; namespace DynamicPluginApiDemo.Utils { public static class DbHelper { public static SqlSugarClient Db; static DbHelper() { if (Db == null) //创建数据库对象 (用法和EF Dappper一样通过new保证线程安全) Db = new SqlSugarClient(new ConnectionConfig() { ConnectionString = "server=192.168.1.61;Database=testdb;Uid=root;Pwd=MyNewPass@123;SslMode=None;AllowPublicKeyRetrieval=true;", DbType = SqlSugar.DbType.MySql, IsAutoCloseConnection = true }, db => { db.Aop.OnLogExecuting = (sql, pars) => { //获取原生SQL推荐 5.1.4.63 性能OK Console.WriteLine(UtilMethods.GetNativeSql(sql, pars)); }; }); } } } using System.Runtime.Loader; namespace DynamicPluginApiDemo.Utils { public class PluginDllHelper { public static List<IPluginDllApi> _labPlugins = new List<IPluginDllApi>(); private static string _pluginFolder = Path.Combine(Directory.GetCurrentDirectory(), "Plugins"); /// <summary> /// 重新加载 /// </summary> public static void ReLoadDll() { if (!Directory.Exists(_pluginFolder)) Directory.CreateDirectory(_pluginFolder); _labPlugins = new List<IPluginDllApi>(); foreach (var dllPath in Directory.GetFiles(_pluginFolder, "*.dll")) { try { var assemblyLoadContext = new AssemblyLoadContext(Path.GetFileNameWithoutExtension(dllPath), true); var assembly = assemblyLoadContext.LoadFromAssemblyPath(dllPath); var pluginTypes = assembly.GetTypes() .Where(t => typeof(IPluginDllApi).IsAssignableFrom(t) && !t.IsInterface && !t.IsAbstract); foreach (var pluginType in pluginTypes) { if (Activator.CreateInstance(pluginType) is IPluginDllApi pluginInstance) { if (pluginInstance != null) _labPlugins.Add((pluginInstance)); } } } catch (Exception ex) { Console.WriteLine($"Failed to load assembly {dllPath}: {ex.Message}"); } } } } }
3，然后我们在程序启动的时候进行调用
4，接下来我们创建一个PluginController.cs控制器，这个控制器实现了动态的路由。代码如下：
using DynamicPluginApiDemo.Utils; using Microsoft.AspNetCore.Http; using Microsoft.AspNetCore.Mvc; using Newtonsoft.Json.Linq; namespace DynamicPluginApiDemo.Controllers { [Route("api/[controller]/{DynamicParam}")] [ApiController] public class PluginController : ControllerBase { /// <summary> /// 动态插件的名称 /// </summary> private readonly string _dynamicParam = string.Empty; public PluginController(IHttpContextAccessor httpContextAccessor) { var dynamicParamKey = httpContextAccessor?.HttpContext?.GetRouteValue("DynamicParam"); if (dynamicParamKey != null) _dynamicParam = dynamicParamKey?.ToString() ?? string.Empty; } // GET: api/ApifulPlugin/apidll/GetRequest/Query?SearchName=AAA [HttpGet("GetRequest/{functionName}")] public IActionResult GetRequest(string functionName, [FromQuery] Dictionary<string, string> queryParameters) { var instance = PluginDllHelper._labPlugins.FirstOrDefault(x => x.Name == _dynamicParam); if (instance == null) return NotFound(); return instance.GetRequest(functionName, queryParameters); } // POST: api/Dynamic/json // Receives query parameters and JSON body [HttpPost("PostRequestBody/{functionName}")] public IActionResult PostRequestBody(string functionName, [FromQuery] Dictionary<string, string> queryParameters, [FromBody] object jsonData) { var instance = PluginDllHelper._labPlugins.FirstOrDefault(x => x.Name == _dynamicParam); if (instance == null) return NotFound(); return instance.PostRequestBody(functionName, queryParameters, jsonData); } // POST: api/Dynamic/form [HttpPost("PostRequestForm/{functionName}")] public IActionResult PostRequestForm(string functionName, [FromQuery] Dictionary<string, string> queryParameters, IFormCollection formData) { var instance = PluginDllHelper._labPlugins.FirstOrDefault(x => x.Name == _dynamicParam); if (instance == null) return NotFound(); return instance.PostRequestForm(functionName, queryParameters, formData); } } }
5，webapi项目的内容差不多了。接下来我们创建一个类库项目，名字叫做BlogPluginApi。然后项目引用一下主项目，并且创建一个BlogPluginApi.cs文件继承主项目的IPluginDllApi。
using BlogPluginApi.Service; using DynamicPluginApiDemo.Utils; using Microsoft.AspNetCore.Http; using Microsoft.AspNetCore.Mvc; using Microsoft.SqlServer.Server; namespace BlogPluginApi { public class BlogPluginApi : IPluginDllApi { public string Name => "BlogPluginApi"; public IActionResult GetRequest(string funName, Dictionary<string, string> queryParameters) { var result = string.Empty; switch (funName) { case "Query": result = BlogService.Query(queryParameters); break; } return new ContentResult { StatusCode = 200, ContentType = "text/plain", Content = result }; } public IActionResult PostRequestBody(string funName, Dictionary<string, string> queryParameters, object jsonData) { var result = string.Empty; switch (funName) { case "Save": result = BlogService.Save(jsonData); break; case "Update": result = BlogService.Update(jsonData); break; case "Delete": result = BlogService.Delete(jsonData); break; } return new ContentResult { StatusCode = 200, ContentType = "text/plain", Content = result }; } public IActionResult PostRequestForm(string funName, Dictionary<string, string> queryParameters, IFormCollection formData) { var result = string.Empty; switch (funName) { case "UploadFile": result = BlogService.UploadFile(queryParameters, formData); break; } return new ContentResult { StatusCode = 200, ContentType = "text/plain", Content = result }; } } }
6，然后我们增加blog表的实体，服务，模型等。当然这些可以放在主项目中，通过项目引用使用主项目的代码。
using SqlSugar; using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace BlogPluginApi.Entitys.Blogs { [SugarTable("BLOG", TableDescription = "博客")] public class Blog { [SugarColumn(ColumnName = "ID", IsIdentity = true, IsPrimaryKey = true)] public int Id { get; set; } [SugarColumn(ColumnName = "Title")] public string Title { get; set; } [SugarColumn(ColumnName = "Context")] public string Context { get; set; } [SugarColumn(ColumnName = "UserId")] public int UserId { get; set; } [SugarColumn(ColumnName = "CreateTime")] public DateTime CreateTime { get; set; } } } using SqlSugar; using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace BlogPluginApi.Models.Blogs { public class BlogInputDto { public int? Id { get; set; } public string? Title { get; set; } public string? Context { get; set; } public int? UserId { get; set; } public DateTime? CreateTime { get; set; } } } using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace BlogPluginApi.Models.Blogs { public class SearchDto { public string SearchName { get; set; } } } using AutoMapper; using BlogPluginApi.Entitys.Blogs; using BlogPluginApi.Models.Blogs; using DynamicPluginApiDemo.Utils; using Microsoft.AspNetCore.Http; using Newtonsoft.Json; using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace BlogPluginApi.Service { public static class BlogService { public static string Query(Dictionary<string, string> queryParameters) { SearchDto searchBlogDto = new SearchDto(); if (queryParameters.TryGetValue("SearchName", out var searchName)) { searchBlogDto.SearchName = searchName; } var result = string.Join(",", DbHelper.Db.Queryable<Blog>().Select(s => s.Title).ToList()); return result; } public static string Delete(object param) { var strParam = param.ToString(); if (string.IsNullOrEmpty(strParam)) return string.Empty; var deleteIds = JsonConvert.DeserializeObject<List<int>>(strParam); if (deleteIds != null) { var count = DbHelper.Db.Deleteable<Blog>().Where(x => deleteIds.Contains(x.Id)).ExecuteCommand(); return count.ToString(); } return string.Empty; } public static string Save(object param) { var strParam = param.ToString(); if (string.IsNullOrEmpty(strParam)) return string.Empty; var inputDto = JsonConvert.DeserializeObject<Blog>(strParam); if (inputDto != null) { var count = DbHelper.Db.Insertable(inputDto).ExecuteCommand(); } return "success"; } public static string Update(object param) { var strParam = param.ToString(); if (string.IsNullOrEmpty(strParam)) return string.Empty; var inputDto = JsonConvert.DeserializeObject<Blog>(strParam); if (inputDto != null) { var count = DbHelper.Db.Updateable(inputDto).ExecuteCommand(); } return "success"; } public static string UploadFile(Dictionary<string, string> queryParameters, IFormCollection formData) { string UploadId = string.Empty; if (queryParameters.TryGetValue("uploadId", out var uploadId)) { UploadId = uploadId; } var file = formData.Files.FirstOrDefault(); if (file != null) return file.FileName; return string.Empty; } } }
7，然后我们生成一下BlogPluginApi项目，把生成的dll文件放在放在主项目的Plugins文件夹下就可以了。
注意：
系统必须被设计为能够识别和管理不同的插件版本，并且能够在运行时安全地切换这些版本。
结语
Web API插件的热插拔是一个复杂但非常有价值的功能，它不仅提高了系统的灵活性和可用性，还增强了用户体验。通过精心规划和技术实践，可以使这一特性成为现代Web应用和服务的一个亮点。
