Java：深度克隆/复制实例的推荐解决方案 [英] Java: recommended solution for deep cloning/copying an instance

问题描述

我想知道是否有推荐的方法在java中进行深度克隆/复制实例。

I'm wondering if there is a recommended way of doing deep clone/copy of instance in java.

我有3个解决方案，但我可以拥有想念一些，我希望得到你的意见

I have 3 solutions in mind, but I can have miss some, and I'd like to have your opinion

编辑：包括Bohzo propositon并改进问题：它更多的是深度克隆而不是浅层克隆。

edit: include Bohzo propositon and refine question: it's more about deep cloning than shallow cloning.

在属性后手动编写克隆属性并检查是否也克隆了可变实例。

亲：

- 控制将执行的操作

- 快速执行

缺点：

- 编写和维护繁琐

- 容易出错（复制/粘贴失败，遗失属性，重新分配的可变属性）

code the clone by hand properties after properties and check that mutable instances are cloned too.
pro:
- control of what will be performed
- quick execution
cons:
- tedious to write and maintain
- bug prone (copy/paste failure, missing property, reassigned mutable property)

使用自己的反射工具或外部帮助器（如jakarta common-beans），可以很容易地编写一个通用的复制方法一行中的工作。

亲：

- 易于编写

- 无需维护

缺点：

- 减少对发生的事情的控制

- 如果反射工具也没有克隆子对象，则容易出现可变对象的错误

- 执行速度较慢

With your own reflection tools or with an external helper (like jakarta common-beans) it is easy to write a generic copy method that will do the job in one line.
pro:
- easy to write
- no maintenance
cons:
- less control of what happens
- bug prone with mutable object if the reflection tool does not clone sub objects too
- slower execution

使用适合您的框架，例如：

commons-lang SerializationUtils

Java深度克隆库

推土机

Kryo

Use a framework that do it for you, like :
commons-lang SerializationUtils
Java Deep Cloning Library
Dozer
Kryo

pro：

- 与反射相同

- 更多地控制将要克隆的内容。

缺点：

- 每一个可变实例被完全克隆，即使在层次结构的末尾 -
- 执行起来可能很慢

pro:
- same as reflection
- more control over what will be exactly be cloned.
cons:
- every mutable instance is fully cloned, even at the end of the hierarchy
- could be very slow to execute

javassit ， BCEL 或 cglib 可能用于生成一个专用的克隆人，就像单手写的一样快。有人为此目的使用其中一种工具知道lib吗？

javassit, BCEL or cglib might be use to generate a dedicated cloner as fast as one hand writed. Someone knows a lib using one of these tools for this purpose ?

我在这里错过了什么？

你会推荐哪一个？

What I have missed here ?
Which one would you recommend ?

谢谢。

推荐答案

用于深度克隆（克隆整个对象层次结构）：

• commons-lang SerializationUtils - 使用序列化 - 如果所有类都在你的控件中，你可以强制实现可序列化。

  For deep cloning (clones the entire object hierarchy):

  • commons-lang SerializationUtils - using serialization - if all classes are in your control and you can force implementing Serializable.

    Java深度克隆库 - 使用反射 - 在您要克隆的类或对象超出您的控制范围（第三方库）并且您无法实现它们的情况下可序列化，或者您不想实现 Serializable 。

    Java Deep Cloning Library - using reflection - in cases when the classes or the objects you want to clone are out of your control (a 3rd party library) and you can't make them implement Serializable, or in cases you don't want to implement Serializable.

    
    

    • commons-beanutils BeanUtils - 在大多数情况下。

    • commons-beanutils BeanUtils - in most cases.

    Spring BeanUtils - 如果你已经使用了spring并因此拥有这个类路径上的实用程序。

    Spring BeanUtils - if you are already using spring and hence have this utility on the classpath.

    我故意省略了自己动手选项 - 上面的API提供了一个很好地控制要克隆的内容和不克隆的内容（例如使用 transient 或 String [] ignoreProperties ），所以重新发明轮子不是首选。

    I deliberately omitted the "do-it-yourself" option - the API's above provide a good control over what to and what not to clone (for example using transient, or String[] ignoreProperties), so reinventing the wheel isn't preferred.

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