山河浪漫，
人间温暖。

Working on the assumption that by ‘not required’ you mean null then…

You have correctly noted that you can supply a default value to the right of a : character. Your example was @Value("${myValue:DEFAULT}").

You are not limited to plain strings as default values. You can use SPEL expressions, and a simple SPEL expression to return null is:

@Value("${myValue:#{null}}")

原文链接：https://www.jianshu.com/p/d24454f40a99