provide a default value using the : operator-优快云博客

本文链接：https://blog.youkuaiyun.com/hshpy/article/details/135996778

博客介绍了Spring Boot中在属性文件里引用外部配置属性的方法，可使用特定语法，若属性未找到，能通过特定运算符提供默认值，还说明了在Spring组件注解中也可采用此方法。

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In Spring Boot, you can use the ${} syntax in property files to reference externalized configuration properties. If a property is not found, you can provide a default value using the : operator. Here's an example:

Assuming you have a property in your application.properties file:

my.property=${property.value:default}

In this example, ${property.value:default} means that Spring Boot will attempt to look up the value for my.property from the externalized configuration. If the value is not found, it will default to "default".

If property.value is defined in your configuration, it will take that value. Otherwise, it will fall back to the default value "default".

You can also use this approach in the @Value annotation in your Spring components:

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class MyComponent {

    @Value("${property.value:default}")
    private String myProperty;

    // Rest of the component code
}

In this case, if property.value is found, myProperty will be assigned that value. Otherwise, it will default to "default".