我有一个定义受保护字段的类。受保护的字段有一个字段初始值设定项。
当我反序列化具体类时,字段初始值设定项不会运行。为什么?解决问题的最佳模式是什么?如果我将初始化移至构造函数中,则也不会调用构造函数。
[DataContract]
public class MyConcrete
{
// FIELD INITIALIZER DOES NOT RUN WHEN COMMENTED IN:
protected readonly Dictionary<int, string> myDict;// = new Dictionary<int, string>();
public MyConcrete()
{
myDict = new Dictionary<int, string>();
}
private bool MyMethod(int key)
{
return myDict.ContainsKey(key);
}
private int myProp;
[DataMember]
public int MyProp
{
get { return myProp; }
set { bool b = MyMethod(value); myProp = value; } // Call MyMethod to provoke error
}
}
原始类层次结构
[DataContract]
public abstract class MyAbstract
{
// THIS INITIALIZER IS NOT RUN WHILE DESERIALIZING:
protected readonly Dictionary<int, string> myDict = new Dictionary<int, string>();
private bool MyMethod(int key)
{
return myDict.ContainsKey(key);
}
private int myProp;
[DataMember]
public int MyProp
{
get { return myProp; }
set { bool b = MyMethod(value); myProp = value; } // Call MyMethod to provoke error
}
}
[DataContract]
public class MyConcrete : MyAbstract
{
}
class Program
{
static void Main(string[] args)
{
string tempfn = Path.GetTempFileName();
MyConcrete concrete = new MyConcrete() { MyProp = 42 };
string data = concrete.SerializeToString<MyConcrete>();
MyConcrete rehydrated = SerializationHelper.DeserializeFromString<MyConcrete>(data);
}
}
支持方法
static public string SerializeToString<T>(this T obj)
{
return SerializationHelper.SerializeToString<T>(obj);
}
static public string SerializeToString<T>(T obj)
{
DataContractSerializer s = new DataContractSerializer(typeof(T));
using (MemoryStream ms = new MemoryStream())
{
s.WriteObject(ms, obj);
ms.Position = 0;
using (StreamReader sr = new StreamReader(ms))
{
string serialized = sr.ReadToEnd();
return serialized;
}
}
}
static public T DeserializeFromString<T>(string serializedDataAsString)
{
DataContractSerializer s = new DataContractSerializer(typeof(T));
using (MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(serializedDataAsString)))
{
object s2 = s.ReadObject(ms);
return (T)s2;
}
}
关于反序列化构造函数和字段初始值设定项都不会被调用 https://stackoverflow.com/a/179486/33969并使用“空白”未初始化的对象来代替。
要解决它,您可以使用OnDeserializing http://msdn.microsoft.com/en-us/library/system.runtime.serialization.ondeserializingattribute.aspx or OnDerserialized http://msdn.microsoft.com/en-us/library/system.runtime.serialization.ondeserializedattribute.aspx属性以使解串器调用具有以下签名的函数:
void OnDeserializing(System.Runtime.Serialization.StreamingContext c);
在该函数中,您可以初始化反序列化过程中遗漏的任何内容。
按照惯例,我倾向于让我的构造函数调用一个方法OnCreated()
然后还有反序列化方法调用相同的东西。然后,您可以在那里处理所有字段初始化,并确保在反序列化之前触发它。
[DataContract]
public abstract class MyAbstract
{
protected Dictionary<int, string> myDict;
protected MyAbstract()
{
OnCreated();
}
private void OnCreated()
{
myDict = new Dictionary<int, string>();
}
[OnDeserializing]
private void OnDeserializing(StreamingContext c)
{
OnCreated();
}
private bool MyMethod(int key)
{
return myDict.ContainsKey(key);
}
private int myProp;
[DataMember]
public int MyProp
{
get { return myProp; }
set { bool b = MyMethod(value); myProp = value; }
}
}
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