java - @PropertySource java.io.FileNotFoundException

Question

我正在测试 Spring 的 @Conditional，其中根据 .properties 文件中存在的值加载 bean。因此，我在 src/main/resources/application-config.properties 中创建了一个 .properties 文件，配置类为:

@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，出现以下异常:原因:java.io.FileNotFoundException:类路径资源[application-config.properties]无法打开，因为它不存在

我通过 main 方法运行它，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，该示例也可以在我的 GitHub 上找到。 。我注意到您的条件实际上是相同的，只是值不同，所以您实际上不需要在那里重复代码。除此之外，这几乎就是您所做的。

我想说你在这里重新发明轮子。 Spring Boot 已经有一个 ConditionalOnProperty这是做什么的。

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:

Greeting: hello.

使用-Dgreeting=hi运行:

输出:

Greeting: hi.