我正在尝试按以下方式序列化Type对象：
Type myType = typeof (StringBuilder);
var serializer = new XmlSerializer(typeof(Type));
TextWriter writer = new StringWriter();
serializer.Serialize(writer, myType);
执行此操作时，对Serialize的调用会引发以下异常：
“不期望System.Text.StringBuilder类型。使用 XmlInclude或SoapInclude属性指定不是的类型 静静地知道。“
我有没有办法序列化Type对象？请注意，我不是要尝试序列化StringBuilder本身，而是序列化Type对象，其中包含有关StringBuilder类的元数据。
答案 0 :(得分：86)
我不知道只能使用包含完全限定名称的字符串创建Type对象。要获取完全限定名称，可以使用以下命令：
string typeName = typeof (StringBuilder).FullName;
然后您可以根据需要保留此字符串，然后重建类型：
Type t = Type.GetType(typeName);
如果您需要创建该类型的实例，可以执行以下操作：
object o = Activator.CreateInstance(t);
如果检查o.GetType（）的值，它将是StringBuilder，正如您所期望的那样。
答案 1 :(得分：11)
我遇到了同样的问题，我的解决方案是创建一个SerializableType类。它可以自由地转换为System.Type和从System.Type转换，但它序列化为字符串。您所要做的就是将变量声明为SerializableType，从那时起您可以将其称为System.Type。
这是班级：
// a version of System.Type that can be serialized
[DataContract]
public class SerializableType
{
public Type type;
// when serializing, store as a string
[DataMember]
string TypeString
{
get
{
if (type == null)
return null;
return type.FullName;
}
set
{
if (value == null)
type = null;
else
{
type = Type.GetType(value);
}
}
}
// constructors
public SerializableType()
{
type = null;
}
public SerializableType(Type t)
{
type = t;
}
// allow SerializableType to implicitly be converted to and from System.Type
static public implicit operator Type(SerializableType stype)
{
return stype.type;
}
static public implicit operator SerializableType(Type t)
{
return new SerializableType(t);
}
// overload the == and != operators
public static bool operator ==(SerializableType a, SerializableType b)
{
// If both are null, or both are same instance, return true.
if (System.Object.ReferenceEquals(a, b))
{
return true;
}
// If one is null, but not both, return false.
if (((object)a == null) || ((object)b == null))
{
return false;
}
// Return true if the fields match:
return a.type == b.type;
}
public static bool operator !=(SerializableType a, SerializableType b)
{
return !(a == b);
}
// we don't need to overload operators between SerializableType and System.Type because we already enabled them to implicitly convert
public override int GetHashCode()
{
return type.GetHashCode();
}
// overload the .Equals method
public override bool Equals(System.Object obj)
{
// If parameter is null return false.
if (obj == null)
{
return false;
}
// If parameter cannot be cast to SerializableType return false.
SerializableType p = obj as SerializableType;
if ((System.Object)p == null)
{
return false;
}
// Return true if the fields match:
return (type == p.type);
}
public bool Equals(SerializableType p)
{
// If parameter is null return false:
if ((object)p == null)
{
return false;
}
// Return true if the fields match:
return (type == p.type);
}
}
以及使用示例：
[DataContract]
public class A
{
...
[DataMember]
private Dictionary<SerializableType, B> _bees;
...
public B GetB(Type type)
{
return _bees[type];
}
...
}
您也可以考虑使用AssemblyQualifiedName而不是Type.FullName - 请参阅@GreyCloud的评论
答案 2 :(得分：7)
Brian's回答很有效（就像GreyCloud在其中一条注释中指出的那样）。 因此，如果类型在另一个程序集中，则需要使用AssemblyQualifiedName，正如GreyCloud也指出的那样。
但是，由于AssemblyQualifiedName保存了版本，如果您的程序集的版本与您拥有该类型的字符串的版本不同，则它将无效。
在我的情况下，这是一个问题，我解决了这个问题：
string typeName = typeof (MyClass).FullName;
Type type = GetTypeFrom(typeName);
object myInstance = Activator.CreateInstance(type);
GetTypeFrom方法
private Type GetTypeFrom(string valueType)
{
var type = Type.GetType(valueType);
if (type != null)
return type;
try
{
var assemblies = AppDomain.CurrentDomain.GetAssemblies();
//To speed things up, we check first in the already loaded assemblies.
foreach (var assembly in assemblies)
{
type = assembly.GetType(valueType);
if (type != null)
break;
}
if (type != null)
return type;
var loadedAssemblies = assemblies.ToList();
foreach (var loadedAssembly in assemblies)
{
foreach (AssemblyName referencedAssemblyName in loadedAssembly.GetReferencedAssemblies())
{
var found = loadedAssemblies.All(x => x.GetName() != referencedAssemblyName);
if (!found)
{
try
{
var referencedAssembly = Assembly.Load(referencedAssemblyName);
type = referencedAssembly.GetType(valueType);
if (type != null)
break;
loadedAssemblies.Add(referencedAssembly);
}
catch
{
//We will ignore this, because the Type might still be in one of the other Assemblies.
}
}
}
}
}
catch(Exception exception)
{
//throw my custom exception
}
if (type == null)
{
//throw my custom exception.
}
return type;
}
如果有人需要，我会张贴此内容。
答案 3 :(得分：2)
根据System.Type [1]的MSDN文档，您应该能够序列化System.Type对象。但是，由于错误明确指向System.Text.StringBuilder，这可能是导致序列化错误的类。
[1]类型类（系统） - http://msdn.microsoft.com/en-us/library/system.type.aspx
答案 4 :(得分：1)
只是看看它的定义，它没有标记为Serializable。如果您确实需要将此数据序列化，则可能必须将其转换为标记为此类的自定义类。
public abstract class Type : System.Reflection.MemberInfo
Member of System
Summary:
Represents type declarations: class types, interface types, array types, value types, enumeration types, type parameters, generic type definitions, and open or closed constructed generic types.
Attributes:
[System.Runtime.InteropServices.ClassInterfaceAttribute(0),
System.Runtime.InteropServices.ComDefaultInterfaceAttribute(System.Runtime.InteropServices._Type),
System.Runtime.InteropServices.ComVisibleAttribute(true)]
答案 5 :(得分：0)
我遇到了这个问题，试图在.net standard 2.0中进行二进制序列化。我最终使用自定义的SurrogateSelector和SerializationBinder解决了这个问题。
TypeSerializationBinder是必需的，因为框架在解决System.RuntimeType之前无法解决SurrogateSelector。我不太明白为什么在此步骤之前必须先解析类型...
代码如下：
// Serializes and deserializes System.Type
public class TypeSerializationSurrogate : ISerializationSurrogate {
public void GetObjectData(object obj, SerializationInfo info, StreamingContext context) {
info.AddValue(nameof(Type.FullName), (obj as Type).FullName);
}
public object SetObjectData(object obj, SerializationInfo info, StreamingContext context, ISurrogateSelector selector) {
return Type.GetType(info.GetString(nameof(Type.FullName)));
}
}
// Just a stub, doesn't need an implementation
public class TypeStub : Type { ... }
// Binds "System.RuntimeType" to our TypeStub
public class TypeSerializationBinder : SerializationBinder {
public override Type BindToType(string assemblyName, string typeName) {
if(typeName == "System.RuntimeType") {
return typeof(TypeStub);
}
return Type.GetType($"{typeName}, {assemblyName}");
}
}
// Selected out TypeSerializationSurrogate when [de]serializing Type
public class TypeSurrogateSelector : ISurrogateSelector {
public virtual void ChainSelector(ISurrogateSelector selector) => throw new NotSupportedException();
public virtual ISurrogateSelector GetNextSelector() => throw new NotSupportedException();
public virtual ISerializationSurrogate GetSurrogate(Type type, StreamingContext context, out ISurrogateSelector selector) {
if(typeof(Type).IsAssignableFrom(type)) {
selector = this;
return new TypeSerializationSurrogate();
}
selector = null;
return null;
}
}
用法示例：
byte[] bytes
var serializeFormatter = new BinaryFormatter() {
SurrogateSelector = new TypeSurrogateSelector()
}
using (var stream = new MemoryStream()) {
serializeFormatter.Serialize(stream, typeof(string));
bytes = stream.ToArray();
}
var deserializeFormatter = new BinaryFormatter() {
SurrogateSelector = new TypeSurrogateSelector(),
Binder = new TypeDeserializationBinder()
}
using (var stream = new MemoryStream(bytes)) {
type = (Type)deserializeFormatter .Deserialize(stream);
Assert.Equal(typeof(string), type);
}