asp.net mvc自定义JsonResult类来防止MaxJsonLength超过限制

据，结果报了500错误，前不久在做一个项目的时候，我用到了mvc的webapi返回了一个大从上面可以看出错误的原因是对象在JavaScriptSerializer序列化的时候超过了默认的最大限制，所以我们需要一个类来重写JsonResult从而允许更大的数据。

using System;
using System.Web.Script.Serialization;
 
namespace System.Web.Mvc
{
    public class LargeJsonResult : JsonResult
    {
        const string JsonRequest_GetNotAllowed = "This request has been blocked because sensitive information could be disclosed 
to third party web sites when this is used in a GET request. To allow GET requests, set JsonRequestBehavior to AllowGet.";
        public LargeJsonResult()
        {
            MaxJsonLength = 1024000;
            RecursionLimit = 100;
        }
 
        public int MaxJsonLength { get; set; }
        public int RecursionLimit { get; set; }
 
        public override void ExecuteResult( ControllerContext context )
        {
            if( context == null )
            {
                throw new ArgumentNullException( "context" );
            }
            if( JsonRequestBehavior == JsonRequestBehavior.DenyGet &&
                String.Equals( context.HttpContext.Request.HttpMethod, "GET", StringComparison.OrdinalIgnoreCase ) )
            {
                throw new InvalidOperationException( JsonRequest_GetNotAllowed );
            }
 
            HttpResponseBase response = context.HttpContext.Response;
 
            if( !String.IsNullOrEmpty( ContentType ) )
            {
                response.ContentType = ContentType;
            }
            else
            {
                response.ContentType = "application/json";
            }
            if( ContentEncoding != null )
            {
                response.ContentEncoding = ContentEncoding;
            }
            if( Data != null )
            {
                JavaScriptSerializer serializer = new JavaScriptSerializer() { MaxJsonLength = MaxJsonLength, RecursionLimit = RecursionLimit };
                response.Write( serializer.Serialize( Data ) );
            }
        }
    }
}

你可以在Action里面使用return new LargeJsonResult(){ Data = data }  来替代 return Json(data).
当然你也可以自己控制JavaScriptSerializer的MaxJsonLength：

return new LargeJsonResult() { Data = output, MaxJsonLength = int.MaxValue };