@PropertySource java.io.FileNotFoundException

Question

我正在测试Spring的@Conditional，根据.properties文件中的值加载bean。因此，我在.properties中创建了一个src/main/resources/application-config.properties文件，配置类如下所示：

@Configuration
@PropertySource(value = {"classpath:application-config.properties"}, ignoreResourceNotFound = false)
@ComponentScan(basePackages = {"com.app.test"})
public class ApplicationContextConfig {...}

我有2个Condition实现如下所示：

public class ConditionalBeanOne implements Condition {
    @Override
    public boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) {
        String name= conditionContext.getEnvironment().getProperty("condition.name");
        return name.equalsIgnoreCase("condition_one");
    }
}


public class ConditionalBeanTwo implements Condition {
    @Override
    public boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) {
        String name= conditionContext.getEnvironment().getProperty("condition.name");
        return name.equalsIgnoreCase("condition_two");
    }
}

我有各自的POJO类：

@Component
@Conditional(value = ConditionalBeanOne.class)
public class BeanOne implements ServiceBean {}

@Component
@Conditional(value = ConditionalBeanTwo.class)
public class BeanTwo implements ServiceBean {}

当我运行应用程序时，我得到以下异常：Caused by: java.io.FileNotFoundException: class path resource [application-config.properties] cannot be opened because it does not exist

我是通过main方法来运行的，如下所示：

public class ConditionalMain {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(ApplicationContextConfig.class);
        .....
    }
}

Answer 1

我无法重现您的问题，因此我根据您的用例创建了一个完整的工作示例，它也可以在我的GitHub上使用。我注意到您的条件是完全相同的，只是值是不同的，所以您不需要在那里复制代码。除此之外，你所做的也差不多。

我得说你在重新发明方向盘。Spring已经有了一个ConditionalOnProperty来实现这个功能。

Application.java

public class Application {
    public static void main(String[] args) {
        try (AnnotationConfigApplicationContext applicationContext =
                     new AnnotationConfigApplicationContext(ApplicationConfig.class)) {

            ApplicationConfig.GreeterService greeterService =
                    applicationContext.getBean(ApplicationConfig.GreeterService.class);

            String actual = greeterService.greeting();

            System.out.printf("Greeting: %s.\n", actual);
        }
    }
}

ApplicationConfig.java

@Configuration
// The / doesn't matter, but I prefer being explicit
@PropertySource("classpath:/application.properties")
@ComponentScan
public class ApplicationConfig {

    @FunctionalInterface
    public static interface GreeterService {
        String greeting();
    }

    @Bean
    @ConditionalOnProperty("hello")
    public GreeterService helloService() {
        return () -> "hello";
    }

    @Bean
    @ConditionalOnProperty("hi")
    public GreeterService hiService() {
        return () -> "hi";
    }
}

ConditionalOnProperty.java

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Conditional(OnPropertyCondition.class)
public @interface ConditionalOnProperty {
    String value() default "";
}

OnPropertyCondition.java

public class OnPropertyCondition implements Condition {
    @Override
    public boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) {
        Map<String, Object> attributes = annotatedTypeMetadata
                .getAnnotationAttributes(ConditionalOnProperty.class.getName());
        String value = (String) attributes.get("value");

        String name = conditionContext.getEnvironment().getProperty("greeting");

        return !isEmpty(name) && name.equalsIgnoreCase(value);
    }
}

application.properties

greeting=hello

正常运行：

输出

问候:你好。

与-Dgreeting=hi一起运行

输出

问候:嗨。