您可以为此使用JavaScriptConverter。但是，与 Json.NET 的 JsonConverter 不同，JavaScriptConverter 只能用于映射到 JSON object 的类型——而不是数组或原始类型。因此，您需要为任何可能包含多态属性（可以是数组或单例项）的对象创建自定义转换器。
假设您有如下所示的 JSON：
{
"name": "my name",
"data": {
"foo": "Foo",
"bar": "Bar"
},
"values": [
3.14,
2.718
]
}
"values" 有时可能是这样的原始值：
"values": 3.14
并且，您希望将其映射到以下 POCO：
public class RootObject
{
public string name { get; set; }
public NestedData data { get; set; }
public float[] Values { get; set; }
}
public class NestedData
{
public string foo { get; set; }
public string bar { get; set; }
}
当JavaScriptConverter.Deserialize() 被传递一个IDictionary<string, object> 的解析值时，要采取的步骤是：
分离任何需要自定义处理的属性（请记住，JavaScriptSerializer 不区分大小写，但字典不区分）。
使用JavaScriptSerializer.ConvertToType<T>() 使用不包含转换器的新序列化程序为任何剩余属性生成默认反序列化。
手动反序列化自定义属性并将其填充到部分反序列化的对象中，然后返回。
对于上面显示的类型，以下转换器在某种程度上基于this answer，可以完成这项工作：
class RootObjectConverter : CustomPropertiesConverter<RootObject>
{
const string ValuesName = "values";
protected override IEnumerable<string> CustomProperties
{
get { return new[] { ValuesName }; }
}
protected override void DeserializeCustomProperties(Dictionary<string, object> customDictionary, RootObject obj, JavaScriptSerializer serializer)
{
object itemCost;
if (customDictionary.TryGetValue(ValuesName, out itemCost) && itemCost != null)
obj.Values = serializer.FromSingleOrArray<float>(itemCost).ToArray();
}
protected override void SerializeCustomProperties(RootObject obj, Dictionary<string, object> dict, JavaScriptSerializer serializer)
{
obj.Values.ToSingleOrArray(dict, ValuesName);
}
}
public abstract class CustomPropertiesConverter<T> : JavaScriptConverter
{
protected abstract IEnumerable<string> CustomProperties { get; }
protected abstract void DeserializeCustomProperties(Dictionary<string, object> customDictionary, T obj, JavaScriptSerializer serializer);
protected abstract void SerializeCustomProperties(T obj, Dictionary<string, object> dict, JavaScriptSerializer serializer);
public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
{
// Detach custom properties
var customDictionary = new Dictionary<string, object>();
foreach (var key in CustomProperties)
{
object value;
if (dictionary.TryRemoveInvariant(key, out value))
customDictionary.Add(key, value);
}
// Deserialize and populate all members other than "values"
var obj = new JavaScriptSerializer().ConvertToType<T>(dictionary);
// Populate custom properties
DeserializeCustomProperties(customDictionary, obj, serializer);
return obj;
}
public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
// Generate a default serialization. Is there an easier way to do this?
var defaultSerializer = new JavaScriptSerializer();
var dict = defaultSerializer.Deserialize<Dictionary<string, object>>(defaultSerializer.Serialize(obj));
// Remove default serializations of custom properties, if present
foreach (var key in CustomProperties)
{
dict.RemoveInvariant(key);
}
// Add custom properties
SerializeCustomProperties((T)obj, dict, serializer);
return dict;
}
public override IEnumerable<Type> SupportedTypes
{
get { return new[] { typeof(T) }; }
}
}
public static class JavaScriptSerializerObjectExtensions
{
public static void ReplaceInvariant<T>(this IDictionary<string, T> dictionary, string key, T value)
{
RemoveInvariant(dictionary, key);
dictionary.Add(key, value);
}
public static bool TryRemoveInvariant<T>(this IDictionary<string, T> dictionary, string key, out T value)
{
if (dictionary == null)
throw new ArgumentNullException();
var keys = dictionary.Keys.Where(k => string.Equals(k, key, StringComparison.OrdinalIgnoreCase)).ToArray();
if (keys.Length == 0)
{
value = default(T);
return false;
}
else if (keys.Length == 1)
{
value = dictionary[keys[0]];
dictionary.Remove(keys[0]);
return true;
}
else
{
throw new ArgumentException(string.Format("Duplicate keys found: {0}", String.Join(",", keys)));
}
}
public static void RemoveInvariant<T>(this IDictionary<string, T> dictionary, string key)
{
if (dictionary == null)
throw new ArgumentNullException();
foreach (var actualKey in dictionary.Keys.Where(k => string.Equals(k, key, StringComparison.OrdinalIgnoreCase)).ToArray())
dictionary.Remove(actualKey);
}
public static void ToSingleOrArray<T>(this ICollection<T> list, IDictionary<string, object> dictionary, string key)
{
if (dictionary == null)
throw new ArgumentNullException();
if (list == null || list.Count == 0)
dictionary.RemoveInvariant(key);
else if (list.Count == 1)
dictionary.ReplaceInvariant(key, list.First());
else
dictionary.ReplaceInvariant(key, list.ToArray());
}
public static List<T> FromSingleOrArray<T>(this JavaScriptSerializer serializer, object value)
{
if (value == null)
return null;
if (value.IsJsonArray())
{
return value.AsJsonArray().Select(i => serializer.ConvertToType<T>(i)).ToList();
}
else
{
return new List<T> { serializer.ConvertToType<T>(value) };
}
}
public static bool IsJsonArray(this object obj)
{
if (obj is string || obj is IDictionary)
return false;
return obj is IEnumerable;
}
public static IEnumerable<object> AsJsonArray(this object obj)
{
return (obj as IEnumerable).Cast<object>();
}
}
然后像这样使用它：
var serializer = new JavaScriptSerializer();
serializer.RegisterConverters(new[] { new RootObjectConverter() });
var root = serializer.Deserialize<RootObject>(json);