.NETMVCJSONJavaScriptSerializer字符串的长度超过
maxJso。。。
1 [ArgumentException: 使⽤ JSON JavaScriptSerializer 序列化或还原序列化期间发⽣错误。字符串的长度超过在 maxJsonLength 属性上设定的值。
2参数名称: input]
3 System.Web.Script.Serialization.JavaScriptSerializer.Deserialize(JavaScriptSerializer serializer, String input, Type type, Int32 depthLimit) +168
4 System.Web.Mvc.JsonValueProviderFactory.GetDeserializedObject(ControllerContext controllerContext) +213
5 System.Web.Mvc.JsonValueProviderFactory.GetValueProvider(ControllerContext controllerContext) +16
6 System.Web.Mvc.ValueProviderFactoryCollection.GetValueProvider(ControllerContext controllerContext) +69
7 System.Web._ValueProvider() +30
由于前端 Post 到 Action 的参数太⼤，超过了2M，还没进⼊后台的 Action ⽅法就报错了。这个问题困扰了很久，⼀直未解决。⽹上了⼏个⽅法都⽆效。
在 fig 中加⼊这些，没有作⽤：
1 2 3 4<appSettings>
<add key="aspnet:MaxJsonDeserializerMembers" value="2147483647" /> <add key="aspnet:UpdatePanelMaxScriptLength" value="2147483647" /> </appSettings>
在 fig 中加⼊这些，也没有作⽤：
1 2 3 4 5 6 7 8<sions>
<scripting>
<webServices>
<jsonSerialization maxJsonLength="2147483647"> </jsonSerialization>
</webServices>
</scripting>
</sions>
仔细看了⼀下异常信息，发现，是在
System.Web.Mvc.JsonValueProviderFactory ⾥调⽤的 JavaScriptSerializer：于是查了⼀下 ，发现 JsonValueProviderFactory 在 System.Web.Mvc.dll 程序集⾥的：
反编译 System.Web.Mvc.dll 到 JsonValueProviderFactory 类：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Configuration;
using System.Globalization;
using System.IO;
using System.Web.Mvc.Properties;
using System.Web.Script.Serialization;
namespace System.Web.Mvc
{
public sealed class JsonValueProviderFactory : ValueProviderFactory
{
private class EntryLimitedDictionary
{
private static int_maximumDepth = JsonValueProviderFactory.EntryLimitedDictionary.GetMaximumDepth();
private readonly IDictionary<string, object> _innerDictionary;
private int_itemCount;
public EntryLimitedDictionary(IDictionary<string, object> innerDictionary)
{
this._innerDictionary = innerDictionary;
}
public void Add(string key, object value)
{
if(++this._itemCount > JsonValueProviderFactory.EntryLimitedDictionary._maximumDepth)
{
throw new InvalidOperationException(MvcResources.JsonValueProviderFactory_RequestTooLarge);
}
this._innerDictionary.Add(key, value);
}
private static int GetMaximumDepth()
{
NameValueCollection appSettings = ConfigurationManager.AppSettings;
if(appSettings != null)
{
string[] values = appSettings.GetValues("aspnet:MaxJsonDeserializerMembers");
int result;
if(values != null&& values.Length > 0 && int.TryParse(values[0], out result))
{
return result;
}
}
return1000;
}
}
private static void AddToBackingStore(JsonValueProviderFactory.EntryLimitedDictionary backingStore, string prefix, object value) {
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IDictionary<string, object> dictionary = value as IDictionary<string, object>;
if(dictionary != null)
{
foreach(KeyValuePair<string, object> current in dictionary)
{
JsonValueProviderFactory.AddToBackingStore(backingStore, JsonValueProviderFactory.MakePropertyKey(prefix, current.Key), current.Value);
}
return;
}
IList list = value as IList;
if(list != null)
{
for(int i = 0; i < list.Count; i++)
{
JsonValueProviderFactory.AddToBackingStore(backingStore, JsonValueProviderFactory.MakeArrayKey(prefix, i), list[i]);
}
return;
}
backingStore.Add(prefix, value);
}
private static object GetDeserializedObject(ControllerContext controllerContext)
{
if(!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase))
{
return null;
}
StreamReader streamReader = new StreamReader(controllerContext.HttpContext.Request.InputStream);
string text = streamReader.ReadToEnd();
if(string.IsNullOrEmpty(text))mvc的controller
{
return null;
}
// 问题就出在这⾥，没有给 javaScriptSerializer.MaxJsonLength 赋值，其默认值是 2097152 字节，即2M
JavaScriptSerializer javaScriptSerializer = new JavaScriptSerializer();
return javaScriptSerializer.DeserializeObject(text);
}
public override IValueProvider GetValueProvider(ControllerContext controllerContext)
{
if(controllerContext == null)
{
throw new ArgumentNullException("controllerContext");
}
object deserializedObject = JsonValueProviderFactory.GetDeserializedObject(controllerContext);
if(deserializedObject == null)
{
return null;
}
Dictionary<string, object> dictionary = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
JsonValueProviderFactory.EntryLimitedDictionary backingStore = new JsonValueProviderFactory.EntryLimitedDictionary(dictionary);
JsonValueProviderFactory.AddToBackingStore(backingStore, string.Empty, deserializedObject);
return new DictionaryValueProvider<object>(dictionary, CultureInfo.CurrentCulture);
}
private static string MakeArrayKey(string prefix, int index)
{
return prefix + "["+ index.ToString(CultureInfo.InvariantCulture) + "]";
}
private static string MakePropertyKey(string prefix, string propertyName)
{
if(!string.IsNullOrEmpty(prefix))
{
return prefix + "."+ propertyName;
}
return propertyName;
}
113}
在 JavaScriptSerializer 没有设置 MaxJsonLength，默认值是 2097152 字节，即2M。
解决此问题的⽅法就是 把 javaScriptSerializer.MaxJsonLength = int.MaxValue; （int.MaxValue 值是 2147483647 字节，即2048M）
⾃⼰重写类 JsonValueProviderFactory 命名为 MyJsonValueProviderFactory：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Configuration;
using System.Globalization;
using System.IO;
using System.Web.Mvc;
using System.Web.Mvc.Properties;
using System.Web.Script.Serialization;
namespace XXX
{
public sealed class MyJsonValueProviderFactory : ValueProviderFactory
{
private class EntryLimitedDictionary
{
private static int_maximumDepth = GetMaximumDepth();
private readonly IDictionary<string, object> _innerDictionary;
private int_itemCount;
public EntryLimitedDictionary(IDictionary<string, object> innerDictionary)
{
this._innerDictionary = innerDictionary;
}
public void Add(string key, object value)
{
if(++this._itemCount > _maximumDepth)
{
//throw new InvalidOperationException(MvcResources.JsonValueProviderFactory_RequestTooLarge);
throw new InvalidOperationException("itemCount is over maximumDepth");
}
this._innerDictionary.Add(key, value);
}
private static int GetMaximumDepth()
{
NameValueCollection appSettings = ConfigurationManager.AppSettings;
if(appSettings != null)
{
string[] values = appSettings.GetValues("aspnet:MaxJsonDeserializerMembers");
int result;
if(values != null&& values.Length > 0 && int.TryParse(values[0], out result))
{
return result;
}
}
return1000;
}
}
private static void AddToBackingStore(EntryLimitedDictionary backingStore, string prefix, object value)
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IDictionary<string, object> dictionary = value as IDictionary<string, object>;
if(dictionary != null)
{
foreach(KeyValuePair<string, object> current in dictionary)
{
AddToBackingStore(backingStore, MakePropertyKey(prefix, current.Key), current.Value);
}
return;
}
IList list = value as IList;
if(list != null)
{
for(int i = 0; i < list.Count; i++)
{
AddToBackingStore(backingStore, MakeArrayKey(prefix, i), list[i]);
}
return;
}
backingStore.Add(prefix, value);
}
private static object GetDeserializedObject(ControllerContext controllerContext)
{
if(!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase)) {
return null;
}
StreamReader streamReader = new StreamReader(controllerContext.HttpContext.Request.InputStream);
string text = streamReader.ReadToEnd();
if(string.IsNullOrEmpty(text))
{
return null;
}
JavaScriptSerializer javaScriptSerializer = new JavaScriptSerializer();
// 解决这个问题：
// 使⽤ JSON JavaScriptSerializer 序列化或还原序列化期间发⽣错误。字符串的长度超过在 maxJsonLength 属性上设定的值。javaScriptSerializer.MaxJsonLength = int.MaxValue;
// ----------------------------------------
return javaScriptSerializer.DeserializeObject(text);
}
public override IValueProvider GetValueProvider(ControllerContext controllerContext)
{
if(controllerContext == null)
{
throw new ArgumentNullException("controllerContext");
}
object deserializedObject = GetDeserializedObject(controllerContext);
if(deserializedObject == null)
{
return null;
}
Dictionary<string, object> dictionary = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase); EntryLimitedDictionary backingStore = new EntryLimitedDictionary(dictionary);
AddToBackingStore(backingStore, string.Empty, deserializedObject);
return new DictionaryValueProvider<object>(dictionary, CultureInfo.CurrentCulture);
}
private static string MakeArrayKey(string prefix, int index)
{
return prefix + "["+ index.ToString(CultureInfo.InvariantCulture) + "]";
}
private static string MakePropertyKey(string prefix, string propertyName)
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