C#中List<T>对象的深度拷贝问题

一、List<T>对象中的T是值类型的情况（int 类型等）

对于值类型的List直接用以下方法就可以复制：

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List<T> oldList = new List<T>();

oldList.Add(..);

List<T> newList = new List<T>(oldList);

二、List<T>对象中的T是引用类型的情况（例如自定义的实体类）

1、对于引用类型的List无法用以上方法进行复制，只会复制List中对象的引用，可以用以下扩展方法复制：

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static class Extensions

{

public static IList<T> Clone<T>(this IList<T> listToClone) where T: ICloneable

{

return listToClone.Select(item => (T)item.Clone()).ToList();

}


//当然前题是List中的对象要实现ICloneable接口</span>

}

2、另一种用序列化的方式对引用对象完成深拷贝，此种方法最可靠

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public static T Clone<T>(T RealObject)



{

using (Stream objectStream = new MemoryStream())

{

//利用 System.Runtime.Serialization序列化与反序列化完成引用对象的复制

IFormatter formatter = new BinaryFormatter();

formatter.Serialize(objectStream, RealObject);

objectStream.Seek(0, SeekOrigin.Begin);

return (T)formatter.Deserialize(objectStream);

}

}

3、利用System.Xml.Serialization来实现序列化与反序列化

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public static T Clone<T>(T RealObject)

{

using(Stream stream=new MemoryStream())

{

XmlSerializer serializer = new XmlSerializer(typeof(T));

serializer.Serialize(stream, RealObject);

stream.Seek(0, SeekOrigin.Begin);

return (T)serializer.Deserialize(stream);

}

}

三、对上述几种对象深拷贝进行测试

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测试如下:

using System;

using System.Collections.Generic;

using System.Collections ;

using System.Linq;

using System.Text;

using System.IO;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Binary;



namespace LINQ

{

[Serializable]

public class tt

{

private string name = "";



public string Name

{

get { return name; }

set { name = value; }

}

private string sex = "";



public string Sex

{

get { return sex; }

set { sex = value; }

}

}



class LINQTest

{

public static T Clone<T>(T RealObject)

{

using (Stream objectStream = new MemoryStream())

{

IFormatter formatter = new BinaryFormatter();

formatter.Serialize(objectStream, RealObject);

objectStream.Seek(0, SeekOrigin.Begin);

return (T)formatter.Deserialize(objectStream);

}

}





public static void Main()

{

List<tt> lsttt = new List<tt>();

tt tt1 = new tt();

tt1.Name = "a1";

tt1.Sex = "20";

lsttt.Add(tt1);

List<tt> l333 = new List<tt>();

l333.Add(Clone<tt>(lsttt[0]));

l333[0].Name = "333333333";

}

}

}