1.安装 Swashbuckle.AspNetCore的Nuget包 2.在Startup类的ConfigureServices方法里面注入服务

public void ConfigureServices(IServiceCollection services)
{
    // 添加Swagger
    services.AddSwaggerGen(c =>
    {
        c.SwaggerDoc("v1", new OpenApiInfo { Title = "API Demo", Version = "v1" });
    });
    services.AddControllers();
}

3.在Startup类的ConfigureServices方法里面注入服务

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }

    // 添加Swagger有关中间件 app.UseSwagger();
    app.UseSwaggerUI(c =>
    {
        c.SwaggerEndpoint("/swagger/v1/swagger.json", "API Demo v1");
    });

    app.UseRouting();

    app.UseAuthorization();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });
}

4.配置Properties/launchSettings.json修改launchUrl

"profiles": {
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "launchUrl": "swagger",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    }
}

5.安装Microsoft.Extensions.PlatformAbstractions包，添加注释说明

/// <summary>
/// 获取默认数据信息
/// </summary>
/// <param name="param">参数</param>
/// <returns>默认数据信息</returns>
[HttpGet]
public IEnumerable<WeatherForecast> Get(string param)
{
    var rng = new Random();
    return Enumerable.Range(1, 5).Select(index => new WeatherForecast
    {
        Date = DateTime.Now.AddDays(index),
        TemperatureC = rng.Next(-20, 55),
        Summary = Summaries[rng.Next(Summaries.Length)]
    })
    .ToArray();
}

6.修改Startup类的ConfigureServices方法，增加下面的方法

public void ConfigureServices(IServiceCollection services)
{
    #region 添加Swagger
    services.AddSwaggerGen(options =>
    {
        options.SwaggerDoc("v1",new OpenApiInfo { Title = "My API", Version = "v1" });
        // 获取xml文件名
        var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
        // 获取xml文件路径
        var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
        // 添加控制器层注释，true表示显示控制器注释
        options.IncludeXmlComments(xmlPath, true);
    });
    #endregion
    services.AddControllers();
}

7.效果