Example tutorial on how to clone an object-C#.Net Tutorial-php.cn

Example tutorial on how to clone an object

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Release： 2017-06-24 09:55:28

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Cloning objects are often encountered during the development process. Sometimes shallow cloning is needed, and sometimes deep cloning is needed. What are the specific differences between them, and what are the implementation methods? Here is a summary.

There are several methods to implement deep cloning.

Manual

The code is as follows:

//手动复制
var user2 = new User
{
	Id = user1.Id,
	Name = new UserName 
	{
		FirstName= user1.Name.FirstName,
		LastName= user1.Name.LastName
	}
};

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Reflection

The code is as follows:

1 //反射2 var user3 = user1.Copy() as User;

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Extension method:

 1 public static class DeepCopyHelper 2 { 3     public static object Copy(this object obj) 4     { 5         Object targetDeepCopyObj; 6         Type targetType = obj.GetType(); 7         //值类型 8         if (targetType.IsValueType == true) 9         {10             targetDeepCopyObj = obj;11         }12         //引用类型 13         else14         {15             targetDeepCopyObj = System.Activator.CreateInstance(targetType);   //创建引用对象 16             System.Reflection.MemberInfo[] memberCollection = obj.GetType().GetMembers();17 18             foreach (System.Reflection.MemberInfo member in memberCollection)19             {20                 if (member.MemberType == System.Reflection.MemberTypes.Field)21                 {22                     System.Reflection.FieldInfo field = (System.Reflection.FieldInfo)member;23                     Object fieldValue = field.GetValue(obj);24                     if (fieldValue is ICloneable)25                     {26                         field.SetValue(targetDeepCopyObj, (fieldValue as ICloneable).Clone());27                     }28                     else29                     {30                         field.SetValue(targetDeepCopyObj, Copy(fieldValue));31                     }32 33                 }34                 else if (member.MemberType == System.Reflection.MemberTypes.Property)35                 {36                     System.Reflection.PropertyInfo myProperty = (System.Reflection.PropertyInfo)member;37                     MethodInfo info = myProperty.GetSetMethod(false);38                     if (info != null)39                     {40                         object propertyValue = myProperty.GetValue(obj, null);41                         if (propertyValue is ICloneable)42                         {43                             myProperty.SetValue(targetDeepCopyObj, (propertyValue as ICloneable).Clone(), null);44                         }45                         else46                         {47                             myProperty.SetValue(targetDeepCopyObj, Copy(propertyValue), null);48                         }49                     }50 51                 }52             }53         }54         return targetDeepCopyObj;55     }56 }

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Serialization

The code is as follows:

1 //序列化2 var user4 = user1.DeepClone();

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Extension method:

 1 /// <summary> 2 /// 深克隆 3 /// 先序列化再反序列化 4 /// </summary> 5 /// <typeparam name="T"></typeparam> 6 /// <param name="obj"></param> 7 /// <returns></returns> 8 public static T DeepClone<T>(this T obj) where T : class 9 {10     return obj != null ? obj.ToJson().FromJson<T>() : null;11 }

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Others also use expressions.

Summary:

Manual copying has the best performance, but when encountering very complex classes, the workload is heavy.
Compared with reflection and serialization, serialization is simpler.

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