.net core中间件

.net core处理流程是一个管道，中间件位于管道内部，有序排队，请求进来时依次通过中间件，且决定是否进入下一中间件，请求返回时，也依次倒叙离开中间件。

指向下一个中间件：return next();

public void Configure(IApplicationBuilder app)
{
    app.Use((context, next) =>
    {
        var cultureQuery = context.Request.Query["culture"];
        if (!string.IsNullOrWhiteSpace(cultureQuery))
        {
            var culture = new CultureInfo(cultureQuery);

            CultureInfo.CurrentCulture = culture;
            CultureInfo.CurrentUICulture = culture;
        }

        // Call the next delegate/middleware in the pipeline
        return next();
    });

    app.Run(async (context) =>
    {
        await context.Response.WriteAsync(
            $"Hello {CultureInfo.CurrentCulture.DisplayName}");
    });
}