Tip14 正確實現淺拷貝和深拷貝
淺拷貝:將對象中的所有字段複製到新的對象(副本)中。複製以後,若在副本中修改值類型的字段的值,不會影響到源對象對應的值,但修改引用類型的字段的值,會影響到源對象本身。
深拷貝:將對象中的所有字段複製到新的對象(副本)中。但是複製以後,對於副本的修改都不會影響到源對象本身。
拷貝建議用類型繼承ICloneable接口。例如:
[Serializable]
class Department
{
public string Name { get; set; }
public override string ToString()
{
return this.Name;
}
}
[Serializable]
class Employee : ICloneable
{
public string IDCode { get; set; }
public int Age { get; set; }
public Department Department { get; set; }
public object Clone()
{
//淺拷貝
return this.MemberwiseClone();
}
/// <summary>
/// 淺拷貝
/// </summary>
/// <returns></returns>
public Employee ShalllowClone()
{
return Clone() as Employee;
}
/// <summary>
/// 深拷貝
/// </summary>
/// <returns></returns>
public Employee DeepClone()
{
//使用序列化來進行深拷貝
using (Stream objectStream = new MemoryStream())
{
IFormatter formatter = new BinaryFormatter();
formatter.Serialize(objectStream, this);
objectStream.Seek(0, SeekOrigin.Begin);
return formatter.Deserialize(objectStream) as Employee;
}
}
}
調用如下:
Employee mike = new Employee() { IDCode = "NB123", Age = 30, Department = new Department() { Name = "Dep1" } };
Employee rose = mike.ShalllowClone() as Employee;
//Employee rose = mike.DeepClone() as Employee;
Console.WriteLine(rose.IDCode);
Console.WriteLine(rose.Age);
Console.WriteLine(rose.Department);
Console.WriteLine("開始改變Mike的值:");
mike.IDCode = "NB456";
mike.Age = 60;
mike.Department.Name = "Dep2";
Console.WriteLine(rose.IDCode);
Console.WriteLine(rose.Age);
Console.WriteLine(rose.Department);
//淺拷貝時輸出如下:
NB123
30
Dep1
開始改變Mike的值:
NB123
30
Dep2
//深拷貝時輸出如下:
NB123
30
Dep1
開始改變Mike的值:
NB123
30
Dep1
可以看到淺拷貝時,改變了源對象mike中的Department的值,副本rose的Department的值也隨之變動。而深拷貝則完全不影響。