判断请求是否为Ajax请求的小妙招

在写后台程序时，有时候需要知道客户端发送的是普通的请求，还是ajax 请求，最近在做项目的时候，有些地方需要判断当前的请求是不是ajax。特地找了下发现，jQuery 发出 ajax 请求时，会在请求头部添加一个名为 X-Requested-With 的信息，信息内容为：XMLHttpRequest。Ajax请求的request headers里都会有一个key为x-requested-with，值为XMLHttpRequest的header，所以我们就可以使用这个特性进行判断。

using System;
namespace CompanyName.ProjectName.Web.Host.Framework
{
public static class RequestExt
{
/// 

/// Determines whether the specified HTTP request is an AJAX request.
/// 
///
/// 
/// true if the specified HTTP request is an AJAX request; otherwise, false.
/// 
/// The HTTP request.
///  
///  The 
///  parameter is null (Nothing in Visual Basic).
public static bool IsAjaxRequest(this Microsoft.AspNetCore.Http.HttpRequest request)
{
if (request == null)
throw new ArgumentNullException("request");
if (request.Headers != null)
return request.Headers["X-Requested-With"] == "XMLHttpRequest";
return false;
}
}
}

using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.ActionConstraints;
using Microsoft.AspNetCore.Routing;
namespace CompanyName.ProjectName.Web.Host.Framework
{
public class AjaxOnlyAttribute : ActionMethodSelectorAttribute
{
public bool Ignore { get; set; }
public AjaxOnlyAttribute(bool ignore = false)
{
Ignore = ignore;
}
public override bool IsValidForRequest(RouteContext routeContext, ActionDescriptor action)
{
if (Ignore)
return true;
var request = routeContext.HttpContext.Request;
if (request != null && request.Headers != null && request.Headers["X-Requested-With"] == "XMLHttpRequest")
return true;
return false;
}
}
}