Java Spring Boot 将 @Value 绑定到 Enum 不区分大小写
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Spring Boot bind @Value to Enum case insensitive
提问by Mikhail Kholodkov
Enum
枚举
public enum Property {
A,
AB,
ABC;
}
Field
场地
@Value("${custom.property}")
protected Property property;
application.properties(lower case)
application.properties（小写）
custom.property=abc
When I'm running application I have an error:
当我运行应用程序时出现错误：
Cannot convert value of type [java.lang.String] to required type [com.xxx.Property]: no matching editors or conversion strategy found.
无法将 [java.lang.String] 类型的值转换为所需类型 [com.xxx.Property]：找不到匹配的编辑器或转换策略。
Whereas (upper case):
而（大写）：
custom.property=ABC
Works fine.
工作正常。
Is there a way to bind the value case insensitive? Like ABC, Abc, AbC, abcany pattern should work.
有没有办法绑定不区分大小写的值？像ABC，Abc，AbC，abc任何模式都应该工作。
NOTE: I saw this question - Spring 3.0 MVC binding Enums Case Sensitivebut in my case I have over 10 enums/values (and expect to have more) classes and to implement 10 different custom property binders would be painful, I need some generic solution.
注意：我看到了这个问题 - Spring 3.0 MVC binding Enums Case Sensitive但在我的例子中我有超过 10 个枚举/值（并且期望有更多）类并且实现 10 个不同的自定义属性绑定器会很痛苦，我需要一些通用的解决方案.
采纳答案by Stephane Nicoll
@Valueand @ConfigurationPropertiesfeatures do not match. I couldn't stress enough how @ConfigurationPropertiesis superior.
@Value和@ConfigurationProperties功能不匹配。我怎么强调都不@ConfigurationProperties为过。
First, you get to design your configuration in a simple POJO that you can inject wherever you want (rather than having expressions in annotation that you can easily break with a typo). Second, the meta-data support means that you can very easilyget auto-completion in your IDE for your own keys.
首先，你可以在一个简单的 POJO 中设计你的配置，你可以在任何你想要的地方注入它（而不是在注释中使用表达式，你可以很容易地因打字错误而中断）。其次，元数据支持意味着您可以非常轻松地在 IDE 中为您自己的密钥自动完成。
And finally, the relaxed binding described in the doc only applies to @ConfigurationProperties. @Valueis a Spring Framework feature and is unaware of relaxed binding. We intend to make that more clear in the doc.
最后，文档中描述的宽松绑定仅适用于@ConfigurationProperties. @Value是 Spring Framework 的一个特性，不知道松散绑定。我们打算在文档中更清楚地说明这一点。
TL;DR abcworks with @ConfigurationPropertiesbut won't with @Value.
TL; DRabc可与@ConfigurationProperties但不会@Value。
回答by jonny.l
In a practical world, this works....
在实际世界中，这是有效的......
public enum Property {
A, a
AB, ab,
ABC, abc,
ABCD, abcd,
ABCDE, abcde;
public boolean isA() {
return this.equals(A) || this.equals(a);
}
public boolean isAB() {
return this.equals(AB) || this.equals(ab);
}
...etc...
}
..although this does break the principle of the enum!
..虽然这确实打破了枚举的原则！
回答by Morten Berg
A problem with ConfigurationPropertis (afaik) is that you cannot use constructor injection, and your class has to be mutable.
ConfigurationPropertis (afaik) 的一个问题是您不能使用构造函数注入，并且您的类必须是可变的。
A workaround (or hack if you like) would be to use SpEL to uppercase the property before looking it up, like this:
一种解决方法（或 hack，如果您愿意）是在查找属性之前使用 SpEL 将其大写，如下所示：
@Value("#{'${custom.property}'.toUpperCase()}") Property property
@Value("#{'${custom.property}'.toUpperCase()}") Property property
This should work since enums instances are constants, and should always be defined in uppercase: https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html
这应该有效，因为枚举实例是常量，并且应始终以大写形式定义：https: //docs.oracle.com/javase/tutorial/java/javaOO/enum.html
