使用注释生成 equals / hashcode / toString
我相信我在某处读到人们在编译时（使用 APT）通过确定哪些字段应该是哈希/相等测试的一部分来生成 equals/hashcode/toString 方法。我在网络上找不到类似的东西（我可能梦想过它？）...
可以这样做：
public class Person {
@Id @GeneratedValue private Integer id;
@Identity private String firstName, lastName;
@Identity private Date dateOfBirth;
//...
}
对于一个实体（所以我们想排除一些字段，比如 id）。
或者像 scala 案例类，即值对象：
@ValueObject
public class Color {
private int red, green, blue;
}
不仅文件变得更可读且更容易编写，而且还有助于确保所有属性都是 equals / hashcode 的一部分（以防您稍后添加另一个属性，而无需相应地更新方法）。
我听说 IDE 中对 APT 的支持不是很好，但我不认为这是一个主要问题。毕竟，测试主要是由持续集成服务器运行的。
知道这是否已经完成了吗？如果没有，为什么？ 谢谢
I believe I read somewhere people generating equals / hashcode / toString methods during compile time (using APT) by identifying which fields should be part of the hash / equality test. I couldn't find anything like that on the web (I might have dreamed it ?) ...
That could be done like that :
public class Person {
@Id @GeneratedValue private Integer id;
@Identity private String firstName, lastName;
@Identity private Date dateOfBirth;
//...
}
For an entity (so we want to exlude some fields, like the id).
Or like a scala case class i.e a value object :
@ValueObject
public class Color {
private int red, green, blue;
}
Not only the file becomes more readable and easier to write, but it also helps ensuring that all the attributes are part of the equals / hashcode (in case you add another attribute later on, without updating the methods accordingly).
I heard APT isn't very well supported in IDE but I wouldn't see that as a major issue. After all, tests are mainly run by continuous integration servers.
Any idea if this has been done already and if not why ?
Thanks
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我为此使用 Project Lombok 。
I'm using Project Lombok for this.
虽然 Pojomatic 不进行编译时字节码操作，但它确实支持轻松创建 equals 、 hashCode 和 toString 方法，使用注释来自定义它们的行为。
While Pojomatic does not do compile-time bytecode manipulation, it does support easy creation of equals, hashCode and toString methods, using annotations to customize their behavior.
Google 在库 AutoValue 中的解决方案： https://github.com/google/auto/tree/master /value 使用@AutoValue注释+编译前生成源。
以下演示文稿讨论了几种竞争解决方案：https://docs.google.com /presentation/d/14u_h-lMn7f1rXE1nDiLX0azS3IkgjGl5uxp5jGJ75RE/编辑
Google's solution in library AutoValue: https://github.com/google/auto/tree/master/value uses @AutoValue annotation + generation of sources before compilation.
Several competing solutions are discussed in the following presentation: https://docs.google.com/presentation/d/14u_h-lMn7f1rXE1nDiLX0azS3IkgjGl5uxp5jGJ75RE/edit