如何在使用@ConditionalOnProperty或@ConditionalOnExpression时检查两个条件

Question

在创建bean时,我需要检查YAML属性文件是否满足两个条件.我该怎么做,因为@ConditionalOnProperty注释只支持一个属性？

Answer 1

使用@ConditionalOnExpression注释和SpEL表达式,如http://docs.spring.io/spring/docs/current/spring-framework-reference/html/expressions.html所述.

例:

@Controller
@ConditionalOnExpression("${controller.enabled} and ${some.value} > 10")
public class WebController {

Answer 2

从一开始@ConditionalOnProperty就可以检查多个属性.name/value属性是一个数组.

@Configuration
@ConditionalOnProperty({ "property1", "property2" })
protected static class MultiplePropertiesRequiredConfiguration {

    @Bean
    public String foo() {
        return "foo";
    }

}

对于具有AND检查的简单布尔属性,您不需要@ConditionalOnExpression.

Answer 3

您可能对AllNestedConditionsSpring Boot 1.3.0中引入的抽象类感兴趣.这允许您创建复合条件,其中您定义的所有条件必须在@Bean您的@Configuration类初始化之前应用.

public class ThisPropertyAndThatProperty extends AllNestedConditions {

    @ConditionalOnProperty("this.property")
    @Bean
    public ThisPropertyBean thisProperty() {
    }

    @ConditionalOnProperty("that.property")
    @Bean
    public ThatPropertyBean thatProperty() {
    }

}

然后你可以这样注释你的@Configuration:

@Conditional({ThisPropertyAndThatProperty.class}
@Configuration

Answer 4

@ConditionalOnExpression("#{${path.to.property.one:true} and ${path.to.property.two:true}}")

如果未找到属性，这两个 true 值都是默认值。