Java 对象深拷贝2种实现

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本文通过两个实例演示了在Java中如何实现对象的深复制和浅复制。首先利用Cloneable接口和Object类中的clone方法实现浅复制，并展示了当原始对象发生变化时，副本对象中引用类型成员变量也会随之改变的情况。接着介绍了通过序列化实现深复制的方法，这种方法能够确保副本对象完全独立于原始对象。

1. 利用 Cloneable 调用Object 中的clone 方法来实现

package com;

public class CopyTest {


    public static void main(String[] args) throws CloneNotSupportedException {
        A a = new A(2,"abc");
        B b = new B();
        b.bParam1 = 10;
        b.bParam2=a;

        // 克隆
        B b1 = (B) b.clone();

        // 修改母版对象
        b.bParam1 = 11;
        b.bParam2.aParam2 = "123";

        System.out.println("---------打印b ---------");
        System.out.println(b.bParam1);
        System.out.println(b.bParam2.aParam1);
        System.out.println(b.bParam2.aParam2);

        System.out.println("---------打印b1 ---------");

        System.out.println(b1.bParam1);
        System.out.println(b1.bParam2.aParam1);
        System.out.println(b1.bParam2.aParam2);

    }


}

class A implements Cloneable{
    public int aParam1;
    public String aParam2;
    public A(int aParam1,String aParam2){
        this.aParam1=aParam1;
        this.aParam2=aParam2;
    }

    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

class B implements Cloneable{
    public int bParam1;
    public A bParam2;

    public Object clone() throws CloneNotSupportedException {
        B b =  (B)super.clone();

        b.bParam2 = (A) bParam2.clone();
        return b;
    }
}

结果

2. 利用Serialization 序列化实现深复制

package com;

import java.io.*;

public class CopyTest {


    public static void main(String[] args) throws Exception {
        A a = new A(2,"abc");
        B b = new B();
        b.bParam1 = 10;
        b.bParam2=a;

        // 克隆
        B b1 = (B) b.cloneObj();

        // 修改母版对象
        b.bParam1 = 8;
        b.bParam2.aParam2 = "test";

        System.out.println("---------打印b ---------");
        System.out.println(b.bParam1);
        System.out.println(b.bParam2.aParam1);
        System.out.println(b.bParam2.aParam2);

        System.out.println("---------打印b1 ---------");

        System.out.println(b1.bParam1);
        System.out.println(b1.bParam2.aParam1);
        System.out.println(b1.bParam2.aParam2);

    }


}

class A implements Serializable {

    public int aParam1;
    public String aParam2;
    public A(int aParam1,String aParam2){
        this.aParam1=aParam1;
        this.aParam2=aParam2;
    }
}

class B implements Serializable{
    public int bParam1;
    public A bParam2;

    public Object cloneObj () throws Exception {
        // 序列化
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(bos);

        oos.writeObject(this);

        // 反序列化
        ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
        ObjectInputStream ois = new ObjectInputStream(bis);

        return ois.readObject();
    }
}