深入详解C#中深拷贝的3种实现方与避坑指南

// 浅拷贝示例
Dog originalDog = new Dog { Name = "Buddy", Toys = new List<string> { "Ball", "Bone" } };
Dog copiedDog = originalDog; // 浅拷贝

copiedDog.Toys.Add("Frisbee");
Console.WriteLine(originalDog.Toys.Count); // 输出3，因为originalDog和copiedDog共享同一个Toys列表

// 深拷贝示例（正确实现）
Dog originalDog = new Dog { Name = "Buddy", Toys = new List<string> { "Ball", "Bone" } };
Dog copiedDog = DeepCopy(originalDog); // 深拷贝

copiedDog.Toys.Add("Frisbee");
Console.WriteLine(originalDog.Toys.Count); // 输出2，因为originalDog和copiedDog是独立的

public static T DeepClone<T>(T obj)
{
    using (MemoryStream stream = new MemoryStream())
    {
        IFormatter formatter = new BinaryFormatter();
        formatter.Serialize(stream, obj);
        stream.Seek(0, SeekOrigin.Begin);
        return (T)formatter.Deserialize(stream);
    }
}

// 不可序列化的示例
[Serializable]
public class Dog
{
    public string Name { get; set; }
    public List<string> Toys { get; set; }
    public Stream PhotoStream { get; set; } // 这个属性无法序列化
}

public static T DeepClone<T>(T obj)
{
    if (obj == null) return default(T);
    
    // 处理值类型
    if (obj is ValueType) return obj;
    
    // 获取类型
    Type type = obj.GetType();
    
    // 创建新对象
    object newObj = Activator.CreateInstance(type);
    
    // 复制属性
    foreach (var prop in type.GetProperties())
    {
        if (prop.CanRead && prop.CanWrite)
        {
            object value = prop.GetValue(obj, null);
            if (value != null && prop.PropertyType.IsClass)
            {
                // 递归复制嵌套对象
                prop.SetValue(newObj, DeepClone(value), null);
            }
            else
            {
                // 直接复制值类型
                prop.SetValue(newObj, value, null);
            }
        }
    }
    
    return (T)newObj;
}

// 使用Newtonsoft.Json实现深拷贝
public static T DeepClone<T>(T obj)
{
    string json = JsonConvert.SerializeObject(obj);
    return JsonConvert.DeserializeObject<T>(json);
}

public interface ICloneable
{
    object Clone();
}

public class Dog : ICloneable
{
    public string Name { get; set; }
    public List<string> Toys { get; set; }

    public object Clone()
    {
        // 这里应该实现深拷贝，但ICloneable的定义导致它只能返回object
        return new Dog { Name = this.Name, Toys = new List<string>(this.Toys) };
    }
}

public class Dog
{
    public string Name { get; set; }
    public Dog Owner { get; set; } // 循环引用：Dog->Dog->Dog...
}

public static T DeepClone<T>(T obj, Dictionary<object, object> visited = null)
{
    if (visited == null) visited = new Dictionary<object, object>();
    
    if (obj == null) return default(T);
    if (visited.ContainsKey(obj)) return (T)visited[obj];
    
    Type type = obj.GetType();
    object newObj = Activator.CreateInstance(type);
    visited[obj] = newObj;
    
    foreach (var prop in type.GetProperties())
    {
        if (prop.CanRead && prop.CanWrite)
        {
            object value = prop.GetValue(obj, null);
            if (value != null && prop.PropertyType.IsClass)
            {
                prop.SetValue(newObj, DeepClone(value, visited), null);
            }
            else
            {
                prop.SetValue(newObj, value, null);
            }
        }
    }
    
    return (T)newObj;
}

public class Dog
{
    public string Name { get; set; }
    public List<string> Toys { get; set; }
    public Stream PhotoStream { get; set; } // 不可序列化
}

public class Dog
{
    public string Name { get; set; }
    public List<string> Toys { get; set; }
    public event EventHandler<EventArgs> OnBark; // 事件无法复制

    public Dog Clone()
    {
        Dog clone = new Dog
        {
            Name = this.Name,
            Toys = new List<string>(this.Toys)
        };
        // 事件无法复制，所以不复制
        return clone;
    }
}

// 多线程示例
private object _lock = new object();
private List<Data> _dataList = new List<Data>();

public void AddData(Data data)
{
    lock (_lock)
    {
        _dataList.Add(data);
    }
}

public List<Data> GetData()
{
    return _dataList.ToList(); // 浅拷贝，不安全
}

public List<Data> GetData()
{
    return DeepClone(_dataList); // 深拷贝，安全
}

// 数据备份示例
public void BackupData(Data data)
{
    Data backup = DeepClone(data);
    // 保存到备份存储
}

// 复杂对象示例
public class Customer
{
    public string Name { get; set; }
    public List<Order> Orders { get; set; }
}

public class Order
{
    public int OrderId { get; set; }
    public List<OrderItem> Items { get; set; }
}

public class OrderItem
{
    public string ProductName { get; set; }
    public int Quantity { get; set; }
}

public Customer DeepCopyCustomer(Customer customer)
{
    return DeepClone(customer);
}