MVC中JSON字符长度超出限制的异常处理

异常信息如下：

使用 JSON JavaScriptSerializer 进行序列化或反序列化时出错。字符串的长度超过了为 maxJsonLength 属性设置的值。

这个异常是在执行MVC中的JsonResult的时抛出的，根据异常的Message得知是序列化的字符串超出了maxJsonLength的限制。并得知这个属性是由JavaScriptSerializer提供的，因为MVC内置的JsonResult是用JavaScriptSerializer进行序列化的。

单纯在web.config中加入下列配置节无效：

<system.web.extensions><scripting><webServices><jsonSerialization maxJsonLength="20971520"/></webServices></scripting>
</system.web.extensions>

还必须重写JsonResult这个类：

ConfigurableJsonResult public class ConfigurableJsonResult : JsonResult{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("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.");}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();ScriptingJsonSerializationSection section = ConfigurationManager.GetSection("system.web.extensions/scripting/webServices/jsonSerialization") as ScriptingJsonSerializationSection;if (section != null){serializer.MaxJsonLength = section.MaxJsonLength;serializer.RecursionLimit = section.RecursionLimit;}response.Write(serializer.Serialize(Data));}}}