C#/.NET Core基础 - 深拷贝的五大类实现方式

在C#和.NET Core开发中，深拷贝是一个常见的需求。深拷贝与浅拷贝不同，深拷贝会递归地复制对象的所有字段，包括嵌套的对象。本文将介绍C#中实现深拷贝的五大类方法及相应的示例代码。

1. 使用序列化与反序列化

序列化与反序列化是一种常用的实现深拷贝的方法。通过将对象序列化为字节流，然后再反序列化回对象，可以实现对象的深拷贝。

示例代码（二进制序列化）：

using System;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

[Serializable]
public class Student
{
public string Name { get; set; }
public int Age { get; set; }
public Department Department { get; set; }

public object Clone()
 {
using (MemoryStream stream = new MemoryStream())
 {
 BinaryFormatter formatter = new BinaryFormatter();
 formatter.Serialize(stream, this);
 stream.Seek(0, SeekOrigin.Begin);
return formatter.Deserialize(stream);
 }
 }
}

[Serializable]
public class Department
{
public string Name { get; set; }
}

public class Program
{
public static void Main()
 {
 Student student1 = new Student
 {
 Name = "Alice",
 Age = 20,
 Department = new Department { Name = "Computer Science" }
 };

 Student student2 = (Student)student1.Clone();
 student2.Department.Name = "Mathematics";

 Console.WriteLine($"Student1 Department: {student1.Department.Name}"); // Output: Student1 Department: Computer Science
 Console.WriteLine($"Student2 Department: {student2.Department.Name}"); // Output: Student2 Department: Mathematics
 }
}

2. 使用反射

反射是另一种实现深拷贝的方法。通过递归地复制对象的所有字段，可以实现深拷贝。

示例代码（使用反射）：

using System;
using System.Reflection;

public class DeepCloner
{
public static T DeepCopy<T>(T obj)
 {
if (obj is string || obj.GetType().IsValueType) return obj;

object retval = Activator.CreateInstance(obj.GetType());

 FieldInfo[] fields = obj.GetType().GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
foreach (FieldInfo field in fields)
 {
 field.SetValue(retval, DeepCopy(field.GetValue(obj)));
 }

return (T)retval;
 }
}

public class Program
{
public static void Main()
 {
 Student student1 = new Student
 {
 Name = "Alice",
 Age = 20,
 Department = new Department { Name = "Computer Science" }
 };

 Student student2 = DeepCloner.DeepCopy(student1);
 student2.Department.Name = "Mathematics";

 Console.WriteLine($"Student1 Department: {student1.Department.Name}"); // Output: Student1 Department: Computer Science
 Console.WriteLine($"Student2 Department: {student2.Department.Name}"); // Output: Student2 Department: Mathematics
 }
}

3. 使用JSON序列化与反序列化

JSON序列化与反序列化也是一种常用的实现深拷贝的方法。通过将对象序列化为JSON字符串，然后再反序列化回对象，可以实现对象的深拷贝。

示例代码（使用Newtonsoft.Json）：

using System;
using Newtonsoft.Json;

public class Student
{
public string Name { get; set; }
public int Age { get; set; }
public Department Department { get; set; }
}

public class Department
{
public string Name { get; set; }
}

public class Program
{
public static void Main()
 {
 Student student1 = new Student
 {
 Name = "Alice",
 Age = 20,
 Department = new Department { Name = "Computer Science" }
 };

string json = JsonConvert.SerializeObject(student1);
 Student student2 = JsonConvert.DeserializeObject<Student>(json);
 student2.Department.Name = "Mathematics";

 Console.WriteLine($"Student1 Department: {student1.Department.Name}"); // Output: Student1 Department: Computer Science
 Console.WriteLine($"Student2 Department: {student2.Department.Name}"); // Output: Student2 Department: Mathematics
 }
}

4. 使用XML序列化与反序列化

与JSON类似，XML序列化与反序列化也是一种实现深拷贝的方法。

示例代码（使用XmlSerializer）：

using System;
using System.IO;
using System.Xml.Serialization;

[Serializable]
public class Student
{
public string Name { get; set; }
public int Age { get; set; }
public Department Department { get; set; }
}

[Serializable]
public class Department
{
public string Name { get; set; }
}

public class Program
{
public static void Main()
 {
 Student student1 = new Student
 {
 Name = "Alice",
 Age = 20,
 Department = new Department { Name = "Computer Science" }
 };

string xml;
using (StringWriter stringWriter = new StringWriter())
 {
 XmlSerializer xmlSerializer = new XmlSerializer(typeof(Student));
 xmlSerializer.Serialize(stringWriter, student1);
 xml = stringWriter.ToString();
 }

 Student student2;
using (StringReader stringReader = new StringReader(xml))
 {
 XmlSerializer xmlSerializer = new XmlSerializer(typeof(Student));
 student2 = (Student)xmlSerializer.Deserialize(stringReader);
 }

 student2.Department.Name = "Mathematics";

 Console.WriteLine($"Student1 Department: {student1.Department.Name}"); // Output: Student1 Department: Computer Science
 Console.WriteLine($"Student2 Department: {student2.Department.Name}"); // Output: Student2 Department: Mathematics
 }
}

5. 使用第三方库

有许多第三方库提供了深拷贝的功能，如AutoMapper、DeepCloner等。

示例代码（使用AutoMapper）：

using System;
using AutoMapper;

public class Student
{
public string Name { get; set; }
public int Age { get; set; }
public Department Department { get; set; }
}

public class Department
{
public string Name { get; set; }
}

public class Program
{
public static void Main()
 {
 MapperConfiguration config = new MapperConfiguration(cfg =>
 {
 cfg.CreateMap<Student, Student>();
 cfg.CreateMap<Department, Department>();
 });

 IMapper mapper = config.CreateMapper();

 Student student1 = new Student
 {
 Name = "Alice",
 Age = 20,
 Department = new Department { Name = "Computer Science" }
 };

 Student student2 = mapper.Map<Student>(student1);
 student2.Department.Name = "Mathematics";

 Console.WriteLine($"Student1 Department: {student1.Department.Name}"); // Output: Student1 Department: Computer Science
 Console.WriteLine($"Student2 Department: {student2.Department.Name}"); // Output: Student2 Department: Mathematics
 }
}

总结

在C#和.NET Core开发中，深拷贝是一个常见的需求。本文介绍了五种实现深拷贝的方法，包括使用序列化与反序列化、反射、JSON序列化与反序列化、XML序列化与反序列化以及第三方库。每种方法都有其适用场景和优缺点，开发者可以根据具体需求选择合适的方法。