java的clone

作项目时有时可能会遇到须要克隆对象的时候，由于有时候对象是直接从别的类get到的，那样引用的是一个对象，修改的话会将原先的对象也修改了。

java的浅克隆，十分简单。可是只会克隆基本的数据类型，当涉及到引用类型时就很差用了。

public class Employee implements Cloneable {
 private String name;
 private String gender;
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public String getGender() {
  return gender;
 }
 public void setGender(String gender) {
  this.gender = gender;
 }
 public Employee clone() throws CloneNotSupportedException {
  return (Employee) super.clone();
 }
}

实现深克隆的话有两种方法，一种就是引用的类也是实现了clone方法的。另外一种是经过序列化来进行克隆。

第一种方法，须要将引用的类须要每一个都clone。

public class Employee implements Cloneable {
 private String name;
 private String gender;
 private Date birthday;
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public String getGender() {
  return gender;
 }
 public void setGender(String gender) {
  this.gender = gender;
 }
 public Date getBirthday() {
  return birthday;
 }
 public void setBirthday(Date birthday) {
  this.birthday = birthday;
 }
 public Employee clone() throws CloneNotSupportedException {
  Employee cloned = (Employee) super.clone();
  cloned.birthday = (Date) birthday.clone();
  return cloned;
 }
}

第二种方法就不须要这么作了。

package clone;
import java.io.*;
import java.sql.Date;
public class Employee implements Serializable {
 private static final long serialVersionUID = 4435396040456359326L;
 private String name;
 private String gender;
 private Date birthday;
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
 public String getGender() {
  return gender;
 }
 public void setGender(String gender) {
  this.gender = gender;
 }
 public Date getBirthday() {
  return birthday;
 }
 public void setBirthday(Date birthday) {
  this.birthday = birthday;
 }
  
 public Object deepClone(Object obj) throws IOException, ClassNotFoundException {
  ByteArrayOutputStream baos = new ByteArrayOutputStream();
  ObjectOutputStream oos = new ObjectOutputStream(baos);
  oos.writeObject(obj);
  ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
  ObjectInputStream ois = new ObjectInputStream(bais);
  return ois.readObject();
 }
}