Spring @Value注释方法，当属性不可用时使用默认值 [英] Spring @Value annotated method, use default value when properties not available

问题描述

我正在将 .properties 文件中的属性注入带有 @Value 的字段中.但是，此属性提供敏感的凭据，因此我将它们从存储库中删除.如果有人要运行项目并且没有带有凭据的.properties文件(默认值将设置为字段)，我仍然希望这样做.

I am injecting properties from .properties file into fields annotated with @Value. However this properties present sensitive credentials, so I remove them from repository. I still want that in case someone wants to run project and doesnt have .properties file with credentials that default values will be set to fields.

即使我将默认值设置为字段本身，当.properties文件不存在时，也会出现异常:

Even if I set default values to field itself I get exception when .properties file is not present:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'xxx': Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'secret' in string value "${secret}"

这是带注释的字段:

 @Value("${secret}")
 private String ldapSecret = "secret";

在这种情况下，我希望只设置纯字符串"secret".

I expected in this case just plain String "secret" would be set.

推荐答案

要准确回答您的问题...

To answer your question exactly...

@Value("${secret:secret}")
private String ldapSecret;

为了示例的完整性，下面还有更多变体...

And a few more variations are below for completeness of the examples...

默认字符串为空:

@Value("${secret:#{null}}")
private String secret;

默认数字:

@Value("${someNumber:0}")
private int someNumber;

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