在特定的类/控制器级别调用AddNewtonsoftJson()方法

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers(options =>
        {
            // 为特定的控制器添加 Newtonsoft.Json 支持
            options.Conventions.Add(new UseNewtonsoftJsonConvention());
        });
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        // ... 其他中间件配置
    }
}

public class UseNewtonsoftJsonConvention : IControllerModelConvention
{
    public void Apply(ControllerModel controller)
    {
        foreach (var action in controller.Actions)
        {
            action.OutputFormatters.Add(new NewtonsoftJsonOutputFormatter());
        }
    }
}

public class UseNewtonsoftJsonAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        var formatter = new NewtonsoftJsonOutputFormatter();
        context.HttpContext.Response.ContentType = "application/json";
        context.Result = new JsonResult(context.ActionArguments, formatter);
    }
}

[UseNewtonsoftJson]
public IActionResult MyAction()
{
    // ...
}