如果这不是 Silverlight,您可以在序列化/反序列化时使用 IDataContractSurrogate 来使用 object[](您的 JSON 中实际存在的内容)而不是 Book。遗憾的是,IDataContractSurrogate(以及使用它的 DataContractJsonSerializer 构造函数的重载)在 Silverlight 中不可用。
在 Silverlight 上,这里有一个 hacky 但简单的解决方法。从实现ICollection<object> 的类型派生Book 类。由于序列化 JSON 中的类型是 object[],因此框架将尽职尽责地将其序列化为您的 ICollection<object>,然后您可以使用您的属性进行包装。
最简单(也是最难的)就是从List<object> 派生。这种简单的 hack 的缺点是用户可以修改基础列表数据并弄乱您的属性。如果您是此代码的唯一用户,那可能没问题。再做一些工作,您可以滚动您自己的 ICollection 实现,并只允许运行足够的方法以使序列化工作,并为其余的抛出异常。我在下面提供了两种方法的代码示例。
如果上面的 hack 对你来说太难看了,我相信还有更优雅的方法来处理这个问题。您可能希望将注意力集中在为您的 collectionitems 属性创建自定义集合类型而不是 List<Book> 上。此类型可能包含一个类型为 List<object[]> 的字段(这是您的 JSON 中的实际类型),您可能能够说服序列化程序填充该字段。然后,您的 IList 实现可以将该数据挖掘到实际的 Book 实例中。
另一行调查可以尝试强制转换。例如,您能否在Book 和string[] 之间实现隐式类型转换,并且序列化是否足够聪明以使用它?我对此表示怀疑,但可能值得一试。
无论如何,这里是上面提到的从 ICollection 获取的代码示例。警告:我还没有在 Silverlight 上验证这些,但它们应该只使用 Silverlight 可访问的类型,所以我认为(手指交叉!)它应该可以正常工作。
简单的黑客示例
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.Serialization.Json;
using System.Runtime.Serialization;
using System.IO;
[DataContract]
class BookCollection
{
[DataMember(Order=1)]
public string collectionname { get; set; }
[DataMember(Order = 2)]
public List<Book> collectionitems { get; set; }
}
[CollectionDataContract]
class Book : List<object>
{
public string Id { get { return (string)this[0]; } set { this[0] = value; } }
public int NumberOfPages { get { return (int)this[1]; } set { this[1] = value; } }
public string Title { get { return (string)this[2]; } set { this[2] = value; } }
}
class Program
{
static void Main(string[] args)
{
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(BookCollection));
string json = "{"
+ "\"collectionname\":\"Books\","
+ "\"collectionitems\": [ "
+ "[\"12345-67890\",201,\"Book One\"],"
+ "[\"09876-54321\",45,\"Book Two\"]"
+ "]"
+ "}";
using (MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json)))
{
BookCollection obj = ser.ReadObject(ms) as BookCollection;
using (MemoryStream ms2 = new MemoryStream())
{
ser.WriteObject(ms2, obj);
string serializedJson = Encoding.UTF8.GetString(ms2.GetBuffer(), 0, (int)ms2.Length);
}
}
}
}
更难、更简单的示例
这是第二个示例,显示了 ICollection 的手动实现,它阻止用户访问集合 - 它支持调用 Add() 3 次(在反序列化期间),但不允许通过 ICollection<T> 进行修改。 ICollection 方法是使用显式接口实现公开的,并且这些方法上有一些属性可以将它们从智能感知中隐藏起来,这应该会进一步减少黑客因素。但是正如你所看到的,这是更多的代码。
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.Serialization.Json;
using System.Runtime.Serialization;
using System.IO;
using System.Diagnostics;
using System.ComponentModel;
[DataContract]
class BookCollection
{
[DataMember(Order=1)]
public string collectionname { get; set; }
[DataMember(Order = 2)]
public List<Book> collectionitems { get; set; }
}
[CollectionDataContract]
class Book : ICollection<object>
{
public string Id { get; set; }
public int NumberOfPages { get; set; }
public string Title { get; set; }
// code below here is only used for serialization/deserialization
// keeps track of how many properties have been initialized
[EditorBrowsable(EditorBrowsableState.Never)]
private int counter = 0;
[EditorBrowsable(EditorBrowsableState.Never)]
public void Add(object item)
{
switch (++counter)
{
case 1:
Id = (string)item;
break;
case 2:
NumberOfPages = (int)item;
break;
case 3:
Title = (string)item;
break;
default:
throw new NotSupportedException();
}
}
[EditorBrowsable(EditorBrowsableState.Never)]
IEnumerator<object> System.Collections.Generic.IEnumerable<object>.GetEnumerator()
{
return new List<object> { Id, NumberOfPages, Title }.GetEnumerator();
}
[EditorBrowsable(EditorBrowsableState.Never)]
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
return new object[] { Id, NumberOfPages, Title }.GetEnumerator();
}
[EditorBrowsable(EditorBrowsableState.Never)]
int System.Collections.Generic.ICollection<object>.Count
{
get { return 3; }
}
[EditorBrowsable(EditorBrowsableState.Never)]
bool System.Collections.Generic.ICollection<object>.IsReadOnly
{ get { throw new NotSupportedException(); } }
[EditorBrowsable(EditorBrowsableState.Never)]
void System.Collections.Generic.ICollection<object>.Clear()
{ throw new NotSupportedException(); }
[EditorBrowsable(EditorBrowsableState.Never)]
bool System.Collections.Generic.ICollection<object>.Contains(object item)
{ throw new NotSupportedException(); }
[EditorBrowsable(EditorBrowsableState.Never)]
void System.Collections.Generic.ICollection<object>.CopyTo(object[] array, int arrayIndex)
{ throw new NotSupportedException(); }
[EditorBrowsable(EditorBrowsableState.Never)]
bool System.Collections.Generic.ICollection<object>.Remove(object item)
{ throw new NotSupportedException(); }
}
class Program
{
static void Main(string[] args)
{
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(BookCollection));
string json = "{"
+ "\"collectionname\":\"Books\","
+ "\"collectionitems\": [ "
+ "[\"12345-67890\",201,\"Book One\"],"
+ "[\"09876-54321\",45,\"Book Two\"]"
+ "]"
+ "}";
using (MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json)))
{
BookCollection obj = ser.ReadObject(ms) as BookCollection;
using (MemoryStream ms2 = new MemoryStream())
{
ser.WriteObject(ms2, obj);
string serializedJson = Encoding.UTF8.GetString(ms2.GetBuffer(), 0, (int)ms2.Length);
}
}
}
}
顺便说一句,我第一次阅读您的问题时,我跳过了重要的 Silverlight 要求。哎呀!无论如何,如果不使用 Silverlight,这是我为该案例编写的解决方案——它更容易,我不妨将它保存在这里以供以后的任何 Google 员工使用。
您正在寻找的(在常规 .NET 框架上,而不是 Silverlight 上)魔法是 IDataContractSurrogate。当您想在序列化/反序列化时将一种类型替换为另一种类型时,请实现此接口。在您的情况下,您可以用object[] 替换Book。
这里有一些代码展示了它是如何工作的:
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.Serialization.Json;
using System.Runtime.Serialization;
using System.IO;
using System.Collections.ObjectModel;
[DataContract]
class BookCollection
{
[DataMember(Order=1)]
public string collectionname { get; set; }
[DataMember(Order = 2)]
public List<Book> collectionitems { get; set; }
}
class Book
{
public string Id { get; set; }
public int NumberOfPages { get; set; }
public string Title { get; set; }
}
// A type surrogate substitutes object[] for Book when serializing/deserializing.
class BookTypeSurrogate : IDataContractSurrogate
{
public Type GetDataContractType(Type type)
{
// "Book" will be serialized as an object array
// This method is called during serialization, deserialization, and schema export.
if (typeof(Book).IsAssignableFrom(type))
{
return typeof(object[]);
}
return type;
}
public object GetObjectToSerialize(object obj, Type targetType)
{
// This method is called on serialization.
if (obj is Book)
{
Book book = (Book) obj;
return new object[] { book.Id, book.NumberOfPages, book.Title };
}
return obj;
}
public object GetDeserializedObject(object obj, Type targetType)
{
// This method is called on deserialization.
if (obj is object[])
{
object[] arr = (object[])obj;
Book book = new Book { Id = (string)arr[0], NumberOfPages = (int)arr[1], Title = (string)arr[2] };
return book;
}
return obj;
}
public Type GetReferencedTypeOnImport(string typeName, string typeNamespace, object customData)
{
return null; // not used
}
public System.CodeDom.CodeTypeDeclaration ProcessImportedType(System.CodeDom.CodeTypeDeclaration typeDeclaration, System.CodeDom.CodeCompileUnit compileUnit)
{
return typeDeclaration; // Not used
}
public object GetCustomDataToExport(Type clrType, Type dataContractType)
{
return null; // not used
}
public object GetCustomDataToExport(System.Reflection.MemberInfo memberInfo, Type dataContractType)
{
return null; // not used
}
public void GetKnownCustomDataTypes(Collection<Type> customDataTypes)
{
return; // not used
}
}
class Program
{
static void Main(string[] args)
{
DataContractJsonSerializer ser =
new DataContractJsonSerializer(
typeof(BookCollection),
new List<Type>(), /* knownTypes */
int.MaxValue, /* maxItemsInObjectGraph */
false, /* ignoreExtensionDataObject */
new BookTypeSurrogate(), /* dataContractSurrogate */
false /* alwaysEmitTypeInformation */
);
string json = "{"
+ "\"collectionname\":\"Books\","
+ "\"collectionitems\": [ "
+ "[\"12345-67890\",201,\"Book One\"],"
+ "[\"09876-54321\",45,\"Book Two\"]"
+ "]"
+ "}";
using (MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json)))
{
BookCollection obj = ser.ReadObject(ms) as BookCollection;
using (MemoryStream ms2 = new MemoryStream())
{
ser.WriteObject(ms2, obj);
string serializedJson = Encoding.UTF8.GetString(ms2.GetBuffer(), 0, (int)ms2.Length);
}
}
}
}