C# 对象的深拷贝

Deep Copy of a C# Object

提问by user70192

I am working on some code that is written in C#. In this app, I have a custom collection defined as follows:

我正在处理一些用 C# 编写的代码。在这个应用程序中，我有一个自定义集合，定义如下：

public class ResultList<T> : IEnumerable<T>
{
  public List<T> Results { get; set; }
  public decimal CenterLatitude { get; set; }
  public decimal CenterLongitude { get; set; }
}

The type used by Results are one of three custom types. The properties of each of the custom types are just primitive types (ints, strings, bools, int?, bool?). Here is an example of one of the custom types:

结果使用的类型是三种自定义类型之一。每个自定义类型的属性只是原始类型（整数、字符串、布尔值、整数？、布尔值？）。以下是其中一种自定义类型的示例：

public class ResultItem
{
  public int ID { get; set; }
  public string Name { get; set; }
  public bool? isLegit { get; set; }
}

How do I perform a deep copy of a ResultList object that I've created. I found this post: Generic method to create deep copy of all elements in a collection. However, I can't figure out how to do it.

如何执行我创建的 ResultList 对象的深层复制。我找到了这篇文章：Generic method to create deep copy of all elements in a collection。但是，我不知道该怎么做。

采纳答案by Rei Mavronicolas

One of the reasons why your ResultList class won't work with Jon Skeet's exampleis because it does not implement the ICloneable interface.

您的 ResultList 类不能与 Jon Skeet 的示例一起使用的原因之一是它没有实现 ICloneable 接口。

Implement ICloneable on all the classes that you need cloned, e.g.

在您需要克隆的所有类上实现 ICloneable，例如

public class ResultItem : ICloneable
{
  public object Clone()
  {
    var item = new ResultItem
                 {
                   ID = ID,
                   Name = Name,
                   isLegit = isLegit
                 };
    return item;
  }
}

And also on ResultList:

还有在 ResultList 上：

public class ResultList<T> : IEnumerable<T>, ICloneable where T : ICloneable
{
  public List<T> Results { get; set; }
  public decimal CenterLatitude { get; set; }
  public decimal CenterLongitude { get; set; }

  public object Clone()
  {
    var list = new ResultList<T>
                 {
                   CenterLatitude = CenterLatitude,
                   CenterLongitude = CenterLongitude,
                   Results = Results.Select(x => x.Clone()).Cast<T>().ToList()
                 };
    return list;
  }
}

Then to make a deep copy of your object:

然后制作对象的深层副本：

resultList.clone();

回答by Douglas

The approach involving the least coding effort is that of serializing and deserializing through a BinaryFormatter.

涉及最少编码工作的方法是通过BinaryFormatter.

You could define the following extension method (taken from Kilhoffer's answer):

您可以定义以下扩展方法（取自Kilhoffer 的回答）：

public static T DeepClone<T>(T obj)
{
    using (var ms = new MemoryStream())
    {
        var formatter = new BinaryFormatter();
        formatter.Serialize(ms, obj);
        ms.Position = 0;
        return (T)formatter.Deserialize(ms);
    }
}

…and then just call:

...然后只需调用：

ResultList<T> clone = DeepClone(original);

回答by Georgi-it

Here is something that I needed and wrote, it uses reflection to copy every property (and private ones if specified)

这是我需要和写的东西，它使用反射来复制每个属性（如果指定的话，还有私有的）

public static class ObjectCloner
{
    public static T Clone<T>(object obj, bool deep = false) where T : new()
    {
        if (!(obj is T))
        {
            throw new Exception("Cloning object must match output type");
        }

        return (T)Clone(obj, deep);
    }

    public static object Clone(object obj, bool deep)
    {
        if (obj == null)
        {
            return null;
        }

        Type objType = obj.GetType();

        if (objType.IsPrimitive || objType == typeof(string) || objType.GetConstructors().FirstOrDefault(x => x.GetParameters().Length == 0) == null)
        {
            return obj;
        }

        List<PropertyInfo> properties = objType.GetProperties().ToList();
        if (deep)
        {
            properties.AddRange(objType.GetProperties(BindingFlags.Instance | BindingFlags.NonPublic)); 
        }

        object newObj = Activator.CreateInstance(objType);

        foreach (var prop in properties)
        {
            if (prop.GetSetMethod() != null)
            {
                object propValue = prop.GetValue(obj, null);
                object clone = Clone(propValue, deep);
                prop.SetValue(newObj, clone, null);
            }
        }

        return newObj;
    }
}

回答by argyle

Expanding on @Georgi-it, I had to modify his code to handle properties whose type inherits List:

扩展@Georgi-it，我不得不修改他的代码来处理类型继承List的属性：

public static class ObjectCloner {
    public static T Clone<T>(object obj, bool deep = false) where T : new() {
        if (!(obj is T)) {
            throw new Exception("Cloning object must match output type");
        }

        return (T)Clone(obj, deep);
    }

    public static object Clone(object obj, bool deep) {
        if (obj == null) {
            return null;
        }

        Type objType = obj.GetType();

        if (objType.IsPrimitive || objType == typeof(string) || objType.GetConstructors().FirstOrDefault(x => x.GetParameters().Length == 0) == null) {
            return obj;
        }

        List<PropertyInfo> properties = objType.GetProperties().ToList();
        if (deep) {
            properties.AddRange(objType.GetProperties(BindingFlags.Instance | BindingFlags.NonPublic));
        }

        object newObj = Activator.CreateInstance(objType);

        foreach (var prop in properties) {
            if (prop.GetSetMethod() != null) {
                var proceed = true;
                if (obj is IList) {
                    var listType = obj.GetType().GetProperty("Item").PropertyType;
                    if (prop.PropertyType == listType) {
                        proceed = false;
                        foreach (var item in obj as IList) {
                            object clone = Clone(item, deep);
                            (newObj as IList).Add(clone);                               
                        }                           
                    }                       
                }

                if (proceed) {
                    object propValue = prop.GetValue(obj, null);
                    object clone = Clone(propValue, deep);
                    prop.SetValue(newObj, clone, null);
                }                   
            }
        }

        return newObj;
    }
}