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[C#进阶系列]课题一:深入解析深拷贝和浅拷贝

热度:37   发布时间:2016-05-05 04:23:51.0
[C#进阶系列]专题一:深入解析深拷贝和浅拷贝

一、前言

  这个星期参加了一个面试,面试中问到深浅拷贝的区别,然后我就简单了讲述了它们的之间的区别,然后面试官又继续问,如何实现一个深拷贝呢?当时只回答回答了一种方式,就是使用反射,然后面试官提示还可以通过反序列化和表达树的方式。然后又继续问,如果用反射来实现深拷贝的话,如何解决互相引用对象的问题呢? 当时我给出的答案是说那就不用反射去实现呗,用反序列化实现呗,或者直接避免使两个对象互相引用呗。然后面试官说,如果一定用反射来写,你是怎么去解决这个问题呢?这时候我就愣住了。

  这样也就有了这篇文章。今天就来深入解析下深浅拷贝的问题。

二、深拷贝 Vs 浅拷贝

  首先,讲到深浅拷贝,自然就有一个问题来了?什么是深拷贝,什么又是浅拷贝呢?下面就具体介绍下它们的定义。

  深拷贝:指的是拷贝一个对象时,不仅仅把对象的引用进行复制,还把该对象引用的值也一起拷贝。这样进行深拷贝后的拷贝对象就和源对象互相独立,其中任何一个对象的改动都不会对另外一个对象造成影响。举个例子,一个人叫张三,然后使用克隆技术以张三来克隆另外一个人叫李四,这样张三和李四就是相互独立的,不管张三缺胳膊还是李四少腿了都不会影响另外一个人。在.NET领域,值对象就是典型的例子,如int, Double以及结构体和枚举等。具体例子如下所示:

int source = 123;// 值类型赋值内部执行深拷贝int copy = source;// 对拷贝对象进行赋值不会改变源对象的值copy = 234;// 同样对源对象赋值也不会改变拷贝对象的值source = 345;

  浅拷贝:指的是拷贝一个对象时,仅仅拷贝对象的引用进行拷贝,但是拷贝对象和源对象还是引用同一份实体。此时,其中一个对象的改变都会影响到另一个对象。例如,一个人一开始叫张三,后来改名字为张老三了,可是他们还是同一个人,不管张三缺胳膊还是张老三少腿,都反应在同一个人身上。在.NET中引用类型就是一个例子。如类类型。具体例子如下所示:

public class Person    {        public string Name { get; set; }    }    class Program    {        static void Main(string[] args)        {            Person sourceP = new Person() { Name = "张三" };            Person copyP = sourceP; // 浅拷贝            copyP.Name = "张老三"; // 拷贝对象改变Name值            // 结果都是"张老三",因为实现的是浅拷贝,一个对象的改变都会影响到另一个对象            Console.WriteLine("Person.Name: [SourceP: {0}] [CopyP:{1}]", sourceP.Name, copyP.Name);            Console.Read();        }    }

三、深浅拷贝的几种实现方式

   上面已经明白了深浅拷贝的定义,至于他们之间的区别也在定义中也有所体现。介绍完了它们的定义和区别之后,自然也就有了如何去实现它们呢?

  对于,浅拷贝的实现方式很简单,.NET自身也提供了实现。我们知道,所有对象的父对象都是System.Object对象,这个父对象中有一个MemberwiseClone方法,该方法就可以用来实现浅拷贝,下面具体看看浅拷贝的实现方式,具体演示代码如下所示:

// 继承ICloneable接口,重新其Clone方法    class ShallowCopyDemoClass : ICloneable    {        public int intValue = 1;        public string strValue = "1";        public PersonEnum pEnum = PersonEnum.EnumA;        public PersonStruct pStruct = new PersonStruct() {  StructValue = 1};        public Person pClass = new Person("1");        public int[] pIntArray = new int[] { 1 };        public string[] pStringArray = new string[] { "1" };        #region ICloneable成员        public object Clone()        {            return this.MemberwiseClone();        }        #endregion     }    class Person    {        public string Name;        public Person(string name)        {            Name = name;        }    }    public enum PersonEnum    {        EnumA = 0,        EnumB = 1    }    public struct PersonStruct    {        public int StructValue;    }

  上面类中重写了IConeable接口的Clone方法,其实现直接调用了Object的MemberwiseClone方法来完成浅拷贝,如果想实现深拷贝,也可以在Clone方法中实现深拷贝的逻辑。接下来就是对上面定义的类进行浅拷贝测试了,看看是否是实现的浅拷贝,具体演示代码如下所示:

class Program    {        static void Main(string[] args)        {            ShallowCopyDemo();            // List浅拷贝的演示            ListShallowCopyDemo();        }        public static void ListShallowCopyDemo()        {            List<PersonA> personList = new List<PersonA>()             {                new PersonA() { Name="PersonA", Age= 10, ClassA= new A() { TestProperty = "AProperty"} },                new PersonA() { Name="PersonA2", Age= 20, ClassA= new A() { TestProperty = "AProperty2"} }            };            // 下面2种方式实现的都是浅拷贝            List<PersonA> personsCopy = new List<PersonA>(personList);            PersonA[] personCopy2 = new PersonA[2];            personList.CopyTo(personCopy2);
       // 由于实现的是浅拷贝,所以改变一个对象的值,其他2个对象的值都会发生改变,因为它们都是使用的同一份实体,即它们指向内存中同一个地址  personsCopy.First().ClassA.TestProperty
= "AProperty3"; WriteLog(string.Format("personCopy2.First().ClassA.TestProperty is {0}", personCopy2.First().ClassA.TestProperty)); WriteLog(string.Format("personList.First().ClassA.TestProperty is {0}", personList.First().ClassA.TestProperty)); WriteLog(string.Format("personsCopy.First().ClassA.TestProperty is {0}", personsCopy.First().ClassA.TestProperty));
       Console.Read();  }
public static void ShallowCopyDemo() { ShallowCopyDemoClass DemoA = new ShallowCopyDemoClass(); ShallowCopyDemoClass DemoB = DemoA.Clone() as ShallowCopyDemoClass ; DemoB.intValue = 2; WriteLog(string.Format(" int->[A:{0}] [B:{1}]", DemoA.intValue, DemoB.intValue)); DemoB.strValue = "2"; WriteLog(string.Format(" string->[A:{0}] [B:{1}]", DemoA.strValue, DemoB.strValue)); DemoB.pEnum = PersonEnum.EnumB; WriteLog(string.Format(" Enum->[A: {0}] [B:{1}]", DemoA.pEnum, DemoB.pEnum)); DemoB.pStruct.StructValue = 2; WriteLog(string.Format(" struct->[A: {0}] [B: {1}]", DemoA.pStruct.StructValue, DemoB.pStruct.StructValue)); DemoB.pIntArray[0] = 2; WriteLog(string.Format(" intArray->[A:{0}] [B:{1}]", DemoA.pIntArray[0], DemoB.pIntArray[0])); DemoB.pStringArray[0] = "2"; WriteLog(string.Format("stringArray->[A:{0}] [B:{1}]", DemoA.pStringArray[0], DemoB.pStringArray[0])); DemoB.pClass.Name = "2"; WriteLog(string.Format(" Class->[A:{0}] [B:{1}]", DemoA.pClass.Name, DemoB.pClass.Name));
       Console.WriteLine();
      }
private static void WriteLog(string msg) { Console.WriteLine(msg); }   } }

  上面代码的运行结果如下图所示:

  从上面运行结果可以看出,.NET中值类型默认是深拷贝的,而对于引用类型,默认实现的是浅拷贝。所以对于类中引用类型的属性改变时,其另一个对象也会发生改变。

  上面已经介绍了浅拷贝的实现方式,那深拷贝要如何实现呢?在前言部分已经介绍了,实现深拷贝的方式有:反射、反序列化和表达式树。在这里,我只介绍反射和反序列化的方式,对于表达式树的方式在网上也没有找到,当时面试官说是可以的,如果大家找到了表达式树的实现方式,麻烦还请留言告知下。下面我们首先来看看反射的实现方式吧:

// 利用反射实现深拷贝        public static T DeepCopyWithReflection<T>(T obj)        {            Type type = obj.GetType();            // 如果是字符串或值类型则直接返回            if (obj is string || type.IsValueType) return obj;            if (type.IsArray)            {                Type elementType = Type.GetType(type.FullName.Replace("[]", string.Empty));                var array = obj as Array;                Array copied = Array.CreateInstance(elementType, array.Length);                for (int i = 0; i < array.Length; i++)                {                    copied.SetValue(DeepCopyWithReflection(array.GetValue(i)), i);                }                return (T)Convert.ChangeType(copied, obj.GetType());            }            object retval = Activator.CreateInstance(obj.GetType());                        PropertyInfo[] properties = obj.GetType().GetProperties(                BindingFlags.Public | BindingFlags.NonPublic                | BindingFlags.Instance | BindingFlags.Static);            foreach (var property in properties)            {                var propertyValue = property.GetValue(obj, null);                if (propertyValue == null)                    continue;                property.SetValue(retval, DeepCopyWithReflection(propertyValue), null);            }            return (T)retval;        }

  反序列化的实现方式,反序列化的方式也可以细分为3种,具体的实现如下所示:

 // 利用XML序列化和反序列化实现        public static T DeepCopyWithXmlSerializer<T>(T obj)        {            object retval;            using (MemoryStream ms = new MemoryStream())            {                XmlSerializer xml = new XmlSerializer(typeof(T));                xml.Serialize(ms, obj);                ms.Seek(0, SeekOrigin.Begin);                retval = xml.Deserialize(ms);                ms.Close();            }            return (T)retval;        }        // 利用二进制序列化和反序列实现        public static T DeepCopyWithBinarySerialize<T>(T obj)        {            object retval;            using (MemoryStream ms = new MemoryStream())            {                BinaryFormatter bf = new BinaryFormatter();                // 序列化成流                bf.Serialize(ms, obj);                ms.Seek(0, SeekOrigin.Begin);                // 反序列化成对象                retval = bf.Deserialize(ms);                ms.Close();            }            return (T)retval;        }        // 利用DataContractSerializer序列化和反序列化实现        public static T DeepCopy<T>(T obj)        {            object retval;            using (MemoryStream ms = new MemoryStream())            {                DataContractSerializer ser = new DataContractSerializer(typeof(T));                ser.WriteObject(ms, obj);                ms.Seek(0, SeekOrigin.Begin);                retval = ser.ReadObject(ms);                ms.Close();            }            return (T)retval;        }                // 表达式树实现        // ....

四、使用反射进行深拷贝如何解决相互引用的问题

  上面反射的实现方式,对于相互引用的对象会出现StackOverflower的错误,由于对象的相互引用,会导致方法循环调用。下面就是一个相互引用对象的例子:

[Serializable]    public class DeepCopyDemoClass    {        public string Name {get;set;}        public int[] pIntArray { get; set; }        public Address Address { get; set; }        public DemoEnum DemoEnum { get; set; }        // DeepCopyDemoClass中引用了TestB对象,TestB类又引用了DeepCopyDemoClass对象,从而造成了相互引用        public TestB TestB {get;set;}        public override string ToString()        {            return "DeepCopyDemoClass";        }    }    [Serializable]    public class TestB    {        public string Property1 { get; set; }        public DeepCopyDemoClass DeepCopyClass { get; set; }        public override string ToString()        {            return "TestB Class";        }    }    [Serializable]    public struct Address    {        public string City { get; set; }    }    public enum DemoEnum    {        EnumA = 0,        EnumB = 1    }

  在面试过程中,针对这个问题的解决方式我回答的是不知道,回来之后思考了之后,也就有了点思路。首先想到的是:能不能用一个字典来记录每个对象被反射的次数,仔细想想可行,于是开始实现,初步修复后的反射实现如下所示:

  public class DeepCopyHelper    {        // 用一个字典来存放每个对象的反射次数来避免反射代码的循环递归        static Dictionary<Type, int> typereflectionCountDic = new Dictionary<Type, int>(); public static T DeepCopyWithReflection_Second<T>(T obj)        {            Type type = obj.GetType();            // 如果是字符串或值类型则直接返回            if (obj is string || type.IsValueType) return obj;            if (type.IsArray)            {                Type elementType = Type.GetType(type.FullName.Replace("[]", string.Empty));                var array = obj as Array;                Array copied = Array.CreateInstance(elementType, array.Length);                for (int i = 0; i < array.Length; i++)                {                    copied.SetValue(DeepCopyWithReflection_Second(array.GetValue(i)), i);                }                return (T)Convert.ChangeType(copied, obj.GetType());            }            // 对于类类型开始记录对象反射的次数            int reflectionCount = Add(typereflectionCountDic, obj.GetType());            if (reflectionCount > 1)                return obj; // 这里有错误            object retval = Activator.CreateInstance(obj.GetType());            PropertyInfo[] properties = obj.GetType().GetProperties(                BindingFlags.Public | BindingFlags.NonPublic                | BindingFlags.Instance | BindingFlags.Static);            foreach (var property in properties)            {                var propertyValue = property.GetValue(obj, null);                if (propertyValue == null)                    continue;                property.SetValue(retval, DeepCopyWithReflection_Second(propertyValue), null);            }            return (T)retval;        }        private static int Add(Dictionary<Type, int> dict, Type key)        {            if (key.Equals(typeof(String)) || key.IsValueType) return 0;            if (!dict.ContainsKey(key))            {                dict.Add(key, 1);                return dict[key];            }            dict[key] += 1;            return dict[key];        }}    

  下面用代码来测试下上面的代码是否已经解决了循环递归的问题,具体的测试代码如下所示:

class Program    {        static void Main(string[] args)        {            //ShallowCopyDemo();            //ListShallowCopyDemo();            DeepCopyDemo();            DeepCopyDemo2();        }        private static void WriteLog(string msg)        {            Console.WriteLine(msg);        }        public static void DeepCopyDemo()        {            DeepCopyDemoClass deepCopyClassA = new DeepCopyDemoClass();            deepCopyClassA.Name = "DeepCopyClassDemo";            deepCopyClassA.pIntArray = new int[] { 1 };            deepCopyClassA.DemoEnum = DemoEnum.EnumA;            deepCopyClassA.Address = new Address() { City = "Shanghai" };            deepCopyClassA.TestB = new TestB() { Property1 = "TestProperty", DeepCopyClass = deepCopyClassA };            // 使用反序列化来实现深拷贝            DeepCopyDemoClass deepCopyClassB = DeepCopyHelper.DeepCopyWithBinarySerialize<DeepCopyDemoClass>(deepCopyClassA);            deepCopyClassB.Name = "DeepCopyClassDemoB";            WriteLog(string.Format("    Name->[A:{0}] [B:{1}]", deepCopyClassA.Name, deepCopyClassB.Name));            deepCopyClassB.pIntArray[0] = 2;            WriteLog(string.Format("    intArray->[A:{0}] [B:{1}]", deepCopyClassA.pIntArray[0], deepCopyClassB.pIntArray[0]));            deepCopyClassB.Address = new Address() { City = "Beijing" };            WriteLog(string.Format("    Addressstruct->[A: {0}] [B: {1}]", deepCopyClassA.Address.City, deepCopyClassB.Address.City));            deepCopyClassB.DemoEnum = DemoEnum.EnumB;            WriteLog(string.Format("    DemoEnum->[A: {0}] [B: {1}]", deepCopyClassA.DemoEnum, deepCopyClassB.DemoEnum));            deepCopyClassB.TestB.Property1 = "TestPropertyB";            WriteLog(string.Format("    Property1->[A:{0}] [B:{1}]", deepCopyClassA.TestB.Property1, deepCopyClassB.TestB.Property1));            WriteLog(string.Format("    TestB.DeepCopyClass.Name->[A:{0}] [B:{1}]", deepCopyClassA.TestB.DeepCopyClass.Name, deepCopyClassB.TestB.DeepCopyClass.Name));            Console.WriteLine();        }        public static void DeepCopyDemo2()        {            DeepCopyDemoClass deepCopyClassA = new DeepCopyDemoClass();            deepCopyClassA.Name = "DeepCopyClassDemo";            deepCopyClassA.pIntArray = new int[] { 1, 2 };            deepCopyClassA.DemoEnum = DemoEnum.EnumA;            deepCopyClassA.Address = new Address() { City = "Shanghai" };            deepCopyClassA.TestB = new TestB() { Property1 = "TestProperty",  DeepCopyClass = deepCopyClassA };            // 使用反射来完成深拷贝            DeepCopyDemoClass deepCopyClassB = DeepCopyHelper.DeepCopyWithReflection_Second<DeepCopyDemoClass>(deepCopyClassA);            //DeepCopyDemoClass deepCopyClassB = DeepCopyHelper.DeepCopyWithReflection<DeepCopyDemoClass>(deepCopyClassA);            deepCopyClassB.Name = "DeepCopyClassDemoB";            WriteLog(string.Format("    Name->[A:{0}] [B:{1}]", deepCopyClassA.Name, deepCopyClassB.Name));            deepCopyClassB.pIntArray[0] = 2;            WriteLog(string.Format("    intArray->[A:{0}] [B:{1}]", deepCopyClassA.pIntArray[0], deepCopyClassB.pIntArray[0]));            deepCopyClassB.Address = new Address() { City = "Beijing" };            WriteLog(string.Format("    Addressstruct->[A: {0}] [B: {1}]", deepCopyClassA.Address.City, deepCopyClassB.Address.City));            deepCopyClassB.DemoEnum = DemoEnum.EnumB;            WriteLog(string.Format("    DemoEnum->[A: {0}] [B: {1}]", deepCopyClassA.DemoEnum, deepCopyClassB.DemoEnum));            deepCopyClassB.TestB.Property1 = "TestPropertyB";            WriteLog(string.Format("    Property1->[A:{0}] [B:{1}]", deepCopyClassA.TestB.Property1, deepCopyClassB.TestB.Property1));            WriteLog(string.Format("    TestB.DeepCopyClass.Name->[A:{0}] [B:{1}]", deepCopyClassA.TestB.DeepCopyClass.Name, deepCopyClassB.TestB.DeepCopyClass.Name));            Console.ReadKey();        }    }    

  此时的运行结果如下图所示:

  刚开始看到这样的运行结果,开心地以为已经解决了循环递归的问题了,因为此时结果成功运行出来了,没有了StackOverflower的错误了。但是仔细一看,反序列化和反射完成的深拷贝的运行结果不一样,如上图中红色圈出来的部分。显然,反序列化的结果是没有错误的,显然目前实现的反射代码还是有问题的。接下来就是思考了。为什么上面反射的代码不正确呢?

  仔细分析DeepCopyWithReflection_Second中的代码,发现下面代码红色部分是错误的:

int reflectionCount = Add(typereflectionCountDic, obj.GetType());            if (reflectionCount > 1)                return obj; // 是错误的

  对DeepCopyWithReflection_Second方法仔细分析,在对TestB进行反射时,当反射到DeepCopyClass属性时,此时会递归调用DeepCopyWithReflection_Second方法,此时在typereflectionCountDic发现DeepCopyDemoClass已经被反射了,则直接返回,这样分析好像没什么错误,但是此时返回的是deepCopyClassA对象,但是我们需要返回的是deepCopyClassB对象,即此时deepCopyClassB对象的内存结构如下图所示:

 

  而我们其实需要deepCopyClassB对象的内存结构如下图所示:

  既然找到了DeepCopyWithReflection_Second的错误原因,那我们就要解决了。上面说我们返回的应该是deepCopyClassB对象,而我们怎么得到创建的deepCopyClassB对象呢?这里我就想能不能用一个变量来保存一开始通过CreateInstance方法创建的deepCopyClassB对象呢?验证想法最好的办法就是代码了,这样我就按照这个思路对DeepCopyWithReflection_Second又进行一次改进,最终的代码如下所示:

 public static T DeepCopyWithReflection_Third<T>(T obj)        {            Type type = obj.GetType();            // 如果是字符串或值类型则直接返回            if (obj is string || type.IsValueType) return obj;            if (type.IsArray)            {                Type elementType = Type.GetType(type.FullName.Replace("[]", string.Empty));                var array = obj as Array;                Array copied = Array.CreateInstance(elementType, array.Length);                for (int i = 0; i < array.Length; i++)                {                    copied.SetValue(DeepCopyWithReflection_Second(array.GetValue(i)), i);                }                return (T)Convert.ChangeType(copied, obj.GetType());            }            int reflectionCount = Add(typereflectionCountDic, obj.GetType());            if (reflectionCount > 1 && obj.GetType() == typeof(DeepCopyDemoClass))                return (T)DeepCopyDemoClasstypeRef; // 返回deepCopyClassB对象            object retval = Activator.CreateInstance(obj.GetType());            if(retval.GetType() == typeof(DeepCopyDemoClass))                DeepCopyDemoClasstypeRef = retval; // 保存一开始创建的DeepCopyDemoClass对象            PropertyInfo[] properties = obj.GetType().GetProperties(                BindingFlags.Public | BindingFlags.NonPublic                | BindingFlags.Instance | BindingFlags.Static);            foreach (var property in properties)            {                var propertyValue = property.GetValue(obj, null);                if (propertyValue == null)                    continue;                property.SetValue(retval, DeepCopyWithReflection_Third(propertyValue), null);            }            return (T)retval;        }

  下面我用DeepCopyWithReflection_Third方法来测试下,具体的测试代码如下所示:

 class Program    {        static void Main(string[] args)        {            //ShallowCopyDemo();            //ListShallowCopyDemo();            DeepCopyDemo();            DeepCopyDemo2();        }         private static void WriteLog(string msg)        {            Console.WriteLine(msg);        }        public static void DeepCopyDemo()        {            DeepCopyDemoClass deepCopyClassA = new DeepCopyDemoClass();            deepCopyClassA.Name = "DeepCopyClassDemo";            deepCopyClassA.pIntArray = new int[] { 1 };            deepCopyClassA.DemoEnum = DemoEnum.EnumA;            deepCopyClassA.Address = new Address() { City = "Shanghai" };            deepCopyClassA.TestB = new TestB() { Property1 = "TestProperty", DeepCopyClass = deepCopyClassA };            // 使用反序列化来实现深拷贝            DeepCopyDemoClass deepCopyClassB = DeepCopyHelper.DeepCopyWithBinarySerialize<DeepCopyDemoClass>(deepCopyClassA);            deepCopyClassB.Name = "DeepCopyClassDemoB";            WriteLog(string.Format("    Name->[A:{0}] [B:{1}]", deepCopyClassA.Name, deepCopyClassB.Name));            deepCopyClassB.pIntArray[0] = 2;            WriteLog(string.Format("    intArray->[A:{0}] [B:{1}]", deepCopyClassA.pIntArray[0], deepCopyClassB.pIntArray[0]));            deepCopyClassB.Address = new Address() { City = "Beijing" };            WriteLog(string.Format("    Addressstruct->[A: {0}] [B: {1}]", deepCopyClassA.Address.City, deepCopyClassB.Address.City));            deepCopyClassB.DemoEnum = DemoEnum.EnumB;            WriteLog(string.Format("    DemoEnum->[A: {0}] [B: {1}]", deepCopyClassA.DemoEnum, deepCopyClassB.DemoEnum));            deepCopyClassB.TestB.Property1 = "TestPropertyB";            WriteLog(string.Format("    Property1->[A:{0}] [B:{1}]", deepCopyClassA.TestB.Property1, deepCopyClassB.TestB.Property1));            WriteLog(string.Format("    TestB.DeepCopyClass.Name->[A:{0}] [B:{1}]", deepCopyClassA.TestB.DeepCopyClass.Name, deepCopyClassB.TestB.DeepCopyClass.Name));            Console.WriteLine();        }        public static void DeepCopyDemo2()        {            DeepCopyDemoClass deepCopyClassA = new DeepCopyDemoClass();            deepCopyClassA.Name = "DeepCopyClassDemo";            deepCopyClassA.pIntArray = new int[] { 1, 2 };            deepCopyClassA.DemoEnum = DemoEnum.EnumA;            deepCopyClassA.Address = new Address() { City = "Shanghai" };            deepCopyClassA.TestB = new TestB() { Property1 = "TestProperty",  DeepCopyClass = deepCopyClassA };            // 使用反射来完成深拷贝            DeepCopyDemoClass deepCopyClassB = DeepCopyHelper.DeepCopyWithReflection_Third<DeepCopyDemoClass>(deepCopyClassA);            //DeepCopyDemoClass deepCopyClassB = DeepCopyHelper.DeepCopyWithReflection<DeepCopyDemoClass>(deepCopyClassA);            deepCopyClassB.Name = "DeepCopyClassDemoB";            WriteLog(string.Format("    Name->[A:{0}] [B:{1}]", deepCopyClassA.Name, deepCopyClassB.Name));            deepCopyClassB.pIntArray[0] = 2;            WriteLog(string.Format("    intArray->[A:{0}] [B:{1}]", deepCopyClassA.pIntArray[0], deepCopyClassB.pIntArray[0]));            deepCopyClassB.Address = new Address() { City = "Beijing" };            WriteLog(string.Format("    Addressstruct->[A: {0}] [B: {1}]", deepCopyClassA.Address.City, deepCopyClassB.Address.City));            deepCopyClassB.DemoEnum = DemoEnum.EnumB;            WriteLog(string.Format("    DemoEnum->[A: {0}] [B: {1}]", deepCopyClassA.DemoEnum, deepCopyClassB.DemoEnum));            deepCopyClassB.TestB.Property1 = "TestPropertyB";            WriteLog(string.Format("    Property1->[A:{0}] [B:{1}]", deepCopyClassA.TestB.Property1, deepCopyClassB.TestB.Property1));            WriteLog(string.Format("    TestB.DeepCopyClass.Name->[A:{0}] [B:{1}]", deepCopyClassA.TestB.DeepCopyClass.Name, deepCopyClassB.TestB.DeepCopyClass.Name));            Console.ReadKey();        }}

  此时的运行结果如下图示所示:

  

  从上面的测试结果可以看出,此时深拷贝的反射实现方法基本上没什么问题了。这个方法也同时解决了相互引用对象的循环递归问题。

五、总结

  到这里,该文章的内容就结束。这里主要记录下自己在一次面试过程中遇到问题的一次总结,从中可以看出,反射进行深拷贝会有很多其他的问题,所以平时还是建议大家使用序列化的形式来进行深拷贝。

  最后附上本文所有源码下载:DeepCopy.zip

 

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