用vs2019加.net core如何創(chuàng)建WeiApi項目

using Microsoft.AspNetCore.Components;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace WEBAPI.Controllers
{

  /// <summary>
  /// 設(shè)置路由
  /// </summary>
  [Route("api/[controller]/[action]")]
  public class Calculation
  {


  }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace WEBAPI.Controllers
{

  /// <summary>
  /// 設(shè)置路由
  /// </summary>
  [Route("api/[controller]/[action]")]
  [ApiController]
  public class Calculation
  {

    /// <summary>
    /// 獲取文本
    /// </summary>
    /// <returns></returns>
    [HttpGet]
    public ActionResult<string> Get()
    {
      return "Hello World!";
    }
    /// <summary>
    /// 兩數(shù)相加
    /// </summary>
    /// <param name="num1">第一個數(shù)</param>
    /// <param name="num2">第二個數(shù)</param>
    /// <returns></returns>
    [HttpGet]
    public ActionResult<int> Sum(int num1, int num2)
    {
      return num1 + num2;
    }
    /// <summary>
    /// 兩數(shù)相減
    /// </summary>
    /// <param name="param">參數(shù)</param>
    /// <returns></returns>
    [HttpPost]
    public ActionResult<int> Subtract(Param param)
    {
      int result = param.num1 - param.num2;
      return result;
    }


  }

  /// <summary>
  /// 參數(shù)
  /// </summary>
  public class Param
  {
    /// <summary>
    /// 第一個數(shù)
    /// </summary>
    public int num1 { get; set; }
    /// <summary>
    /// 第二個數(shù)
    /// </summary>
    public int num2 { get; set; }
  }
}

services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
      //配置Swagger
      //注冊Swagger生成器，定義一個Swagger 文檔
      services.AddSwaggerGen(c =>
      {
        c.SwaggerDoc("v1", new OpenApiInfo
        {
          Version = "v1",
          Title = "接口文檔",
          Description = "RESTful API"
        });
        // 為 Swagger 設(shè)置xml文檔注釋路徑
        var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
        var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
        c.IncludeXmlComments(xmlPath);
      });
      services.AddMvc(x => x.EnableEndpointRouting = false);

//啟用中間件服務(wù)生成Swagger
      app.UseSwagger();
      //啟用中間件服務(wù)生成Swagger，指定Swagger JSON終結(jié)點
      app.UseSwaggerUI(c =>
      {
        c.SwaggerEndpoint("/swagger/v1/swagger.json", "Web App V1");
        c.RoutePrefix = string.Empty;//設(shè)置根節(jié)點訪問
      });
      app.UseMvc();