楼主是一名asp.net攻城狮，最近经常跑java组客串帮忙开发，所以最近对java的一些基础知识特别上心。却遇到需要将一个对象深拷贝出来做其他事情，而原对象保持原有状态的情况。（实在是不想自己new一个出来，然后对着一堆字段赋值......好吧，再此之前我没有关心是否项目框架有深拷贝的方法），然后就想着用反射实现吧....接下来
是我自己的原因，还是真的不存在这样的纯用反射实现的深拷贝方式....（c#是有纯反射实现的）
但也不能算自己白忙活吧，也找到了其他实现深拷贝的方式（但是每种方式我都觉得并不是太合理，也许是因为c#的方式带入了吧，最后贴出c#版本纯反射实现深拷贝的代码）
方式一：实现Cloneable
接口，重写clone方法
实体类：一个轮胎类，一个车辆类，车辆中包含轮胎
1 /**轮胎类**/ 2 public class Tire implements Cloneable { 3 public String color; 4 public int radius; 5 public Tire(){} 6 public Tire(String color, int radius) { 7 this.color = color; 8 this.radius = radius; 9 }10 11 @Override12 protected Object clone() throws CloneNotSupportedException {13 return super.clone();14 }15 }16 /**车辆类**/17 public class Car implements Cloneable{18 public String name;19 public String color;20 public Tire tire;21 public Car() {}22 public Car(String name, String color, Tire tire) {23 this.name = name;24 this.color = color;25 this.tire = tire;26 }27 public void whistle(){28 System.out.println("汽车"+this.name+" 鸣笛...");29 }30 public String getName() {31 return name;32 }33 public void setName(String name) {34 this.name = name;35 }36 public String getColor() {37 return color;38 }39 public void setColor(String color) {40 this.color = color;41 }42 public Tire getTire() {43 return tire;44 }45 public void setTire(Tire tire) {46 this.tire = tire;47 }48 @Override49 protected Object clone() throws CloneNotSupportedException {50 return super.clone();51 }52 }
单元测试：
1 @Test 2 public void test() throws CloneNotSupportedException { 3 Tire tire = new Tire("black",100); 4 Car car = new Car("奔驰","white",tire); 5 Car car_copy = (Car)car.clone(); 6 System.out.println("car:"+car.hashCode()+" car.tire:"+car.tire.hashCode()); 7 System.out.println("car_copy:"+car_copy.hashCode()+" car_copy.tire:"+car_copy.tire.hashCode()); 8 car_copy.color = "blue"; 9 System.out.println("car_copy:"+car_copy.color+" car:"+car.color);10 }
输出结果：
car:1223737555 car.tire:906199566car_copy:542081238 car_copy.tire:906199566car_copy:blue car:white
从结果可以的之，car与car_copy的内存地址并不一致，但car.tire与car_copy.tire的内存地址却是一致的，说明“奔驰”车确实又造出了一辆，但却公用同一幅轮胎（这种情形....哈哈哈），好吧，也就是只复制了tire的引用，这可以说是深拷贝的不彻底 （hashCode()的值可以当作是内存地址来理解），那么要怎样才能彻底，真正的深拷贝？
修改Car类中的clone方法：
1 @Override2 protected Object clone() throws CloneNotSupportedException {3 Car car = (Car)super.clone();4 car.tire = (Tire)car.tire.clone();5 return car;6 }
输出结果：
car:1223737555 car.tire:906199566car_copy:542081238 car_copy.tire:1133736492car_copy:blue car:white
这样最终实现了，但这种方式用到项目中并不是很合适吧，每个需要深拷贝的类，都要实现Cloneable接口，并覆盖其clone方法，遇到引用其他类时候更是需要修改clone方法，要是引用其他类，其他类再引用其他类呢？这不好吧......
方式二：通过序列化与反序列化实现(实现
Serializable接口)
实体类：与第一种方式类似，换成实现Serializable接口，去掉clone方法
/**轮胎类**/@SuppressWarnings("serial")public class Tire implements java.io.Serializable { public String color; public int radius; public Tire(){} public Tire(String color, int radius) { this.color = color; this.radius = radius; }}/**车辆类**/@SuppressWarnings("serial")public class Car implements java.io.Serializable{ public String name; public String color; public Tire tire; public Car() {} public Car(String name, String color, Tire tire) { this.name = name; this.color = color; this.tire = tire; } public void whistle(){ System.out.println("汽车"+this.name+" 鸣笛..."); } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getColor() { return color; } public void setColor(String color) { this.color = color; } public Tire getTire() { return tire; } public void setTire(Tire tire) { this.tire = tire; }}
深拷贝方法：
1 @SuppressWarnings("unchecked") 2 public static Object deepClone(Object obj) 3 { 4 Object copyObj = null; 5 ObjectOutputStream out = null; 6 ObjectInputStream in = null; 7 try { 8 // 序列化 9 ByteArrayOutputStream bufferOut = new ByteArrayOutputStream();10 out = new ObjectOutputStream(bufferOut);11 12 out.writeObject(obj);13 14 // 反序列化15 ByteArrayInputStream bufferIn = new ByteArrayInputStream(bufferOut.toByteArray());16 in = new ObjectInputStream(bufferIn);17 copyObj = in.readObject();18 } catch (Exception e) {19 e.printStackTrace();20 throw new RuntimeException(e); 21 }finally{22 try{23 if(in != null){24 in.close();25 }26 if(out!=null){27 out.close();28 }29 }catch(IOException e){30 throw new RuntimeException(e);31 }32 }33 return copyObj;34 }
单元测试：
1 @Test 2 public void test() throws CloneNotSupportedException { 3 Tire tire = new Tire("black",100); 4 Car car = new Car("奔驰","white",tire); 5 Car car_copy = (Car)deepClone(car); 6 System.out.println("car:"+car.hashCode()+" car.tire:"+car.tire.hashCode()); 7 System.out.println("car_copy:"+car_copy.hashCode()+" car_copy.tire:"+car_copy.tire.hashCode()); 8 car_copy.color = "blue"; 9 System.out.println("car_copy:"+car_copy.color+" car:"+car.color);10 }
输出结果：
car:2019524978 car.tire:855703640car_copy:1407965019 car_copy.tire:545768040car_copy:blue car:white
从结果集中可以看出是深拷贝是正确的，但是每个类还是需要实现Serializable，好像也不合适吧......
优化一下深拷贝方法：将其换成泛型，这样拷贝出来就不需要强转了（好吧，其实也没比上面的方法好到哪去...）
1 @SuppressWarnings("unchecked") 2 public static <T> T deepClone(T obj) 3 { 4 T copyObj = null; 5 ObjectOutputStream out = null; 6 ObjectInputStream in = null; 7 try { 8 // 序列化 9 ByteArrayOutputStream bufferOut = new ByteArrayOutputStream();10 out = new ObjectOutputStream(bufferOut);11 12 out.writeObject(obj);13 14 // 反序列化15 ByteArrayInputStream bufferIn = new ByteArrayInputStream(bufferOut.toByteArray());16 in = new ObjectInputStream(bufferIn);17 copyObj = (T)in.readObject();18 } catch (Exception e) {19 e.printStackTrace();20 throw new RuntimeException(e); 21 }finally{22 try{23 if(in != null){24 in.close();25 }26 if(out!=null){27 out.close();28 }29 }catch(IOException e){30 throw new RuntimeException(e);31 }32 }33 return copyObj;34 }
通过序列化与反序列化深拷贝还有更简单的实现方式，就是需要导个包（拷贝的类也必须实现Serializable接口），当然，我已经为你们准备好了 点击->org.apache.commons.lang
深拷贝方法：就一行代码...
1 public Object deepClone(Object obj){2 return org.apache.commons.lang.SerializationUtils.clone((Serializable)obj);3 }
好了，java的暂时就到这里了，当然对于这两种方式并不是很满意...
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C#深拷贝 反射实现
下面方法是c#的深拷贝，纯反射实现，无需实现任何接口，哦对，需要实体类有个无参的构造方法，简单使用强大，微软**好啊......有需要用到的同学就拿去用吧，目前经过一个几百W的项目框架中考验，真的强大实用
1 /// <summary> 2 /// 对象拷贝 3 /// </summary> 4 /// <param name="obj">被复制对象</param> 5 /// <returns>新对象</returns> 6 private object CopyOjbect(object obj) { 7 if (obj == null) { 8 return null; 9 }10 Object targetDeepCopyObj;11 Type targetType = obj.GetType();12 //值类型 13 if (targetType.IsValueType == true) {14 targetDeepCopyObj = obj;15 }16 //引用类型 17 else {18 targetDeepCopyObj = System.Activator.CreateInstance(targetType); //创建引用对象 19 System.Reflection.MemberInfo[] memberCollection = obj.GetType().GetMembers();20 21 foreach (System.Reflection.MemberInfo member in memberCollection) {22 //拷贝字段23 if (member.MemberType == System.Reflection.MemberTypes.Field)24 {25 System.Reflection.FieldInfo field = (System.Reflection.FieldInfo)member;26 Object fieldValue = field.GetValue(obj);27 if (fieldValue is ICloneable)28 {29 field.SetValue(targetDeepCopyObj, (fieldValue as ICloneable).Clone());30 }31 else32 {33 field.SetValue(targetDeepCopyObj, CopyOjbect(fieldValue));34 }35 36 }//拷贝属性37 else if (member.MemberType == System.Reflection.MemberTypes.Property) {38 System.Reflection.PropertyInfo myProperty = (System.Reflection.PropertyInfo)member;39 40 MethodInfo info = myProperty.GetSetMethod(false);41 if (info != null) {42 try {43 object propertyValue = myProperty.GetValue(obj, null);44 if (propertyValue is ICloneable) {45 myProperty.SetValue(targetDeepCopyObj, (propertyValue as ICloneable).Clone(), null);46 }47 else {48 myProperty.SetValue(targetDeepCopyObj, CopyOjbect(propertyValue), null);49 }50 }51 catch (System.Exception ex) {52 53 }54 }55 }56 }57 }58 return targetDeepCopyObj;59 }
原标题：java深拷贝与c#深拷贝的实现
关键词：C#
我知道了 