在 Spring Cloud 体系的项目中,配置中心主要用于提供分布式的配置管理,其中有一个重要的注解:@RefreshScope,如果代码中需要动态刷新配置,在需要的类上加上该注解就行。本文分享一下笔者遇到与 @ConditionalOnSingleCandidate 注解冲突的问题
问题背景
项目再引入 RabbitMQ,在自定义 connectionFactory 时,手滑加上了 @RefreshScope
@Bean
@RefreshScope
public CachingConnectionFactory connectionFactory() {
CachingConnectionFactory connectionFactory = new CachingConnectionFactory();
connectionFactory.setAddresses("172.17.0.111");
connectionFactory.setUsername("guest");
connectionFactory.setPassword("guest");
connectionFactory.setVirtualHost("/");
return connectionFactory;
}
系统报错无法注入 RabbitTemplate
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'com.pig4cloud.course.refresh.bug.RefreshBugApplicationTest':
Unsatisfied dependency expressed through field 'rabbitTemplate'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException:
No qualifying bean of type 'org.springframework.amqp.rabbit.core.RabbitTemplate' available: expected at least 1 bean which qualifies as autowire candidate.
Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
排查
-
- 默认情况下 spring-boot-starter-amqp 会默认给我们注入 rabbitTemplate 实现
RabbitAutoConfiguration#rabbitTemplate
@Bean
@ConditionalOnSingleCandidate(ConnectionFactory.class)
@ConditionalOnMissingBean(RabbitOperations.class)
public RabbitTemplate rabbitTemplate(RabbitTemplateConfigurer configurer, ConnectionFactory connectionFactory) {
RabbitTemplate template = new RabbitTemplate();
configurer.configure(template, connectionFactory);
return template;
}
-
- 开启 Spring Boot 启动 debugger 日志,查看注入信息
RabbitAutoConfiguration.RabbitTemplateConfiguration#rabbitTemplate:
Did not match:
- @ConditionalOnSingleCandidate (types: org.springframework.amqp.rabbit.connection.ConnectionFactory; SearchStrategy: all)
did not find a primary bean from beans 'connectionFactory', 'scopedTarget.connectionFactory' (OnBeanCondition)
提示 ConditionalOnSingleCandidate
注解的方法不能查找到唯一 ConnectionFactory
实现
-
- 使用 @RefreshScope 注解的 bean,默认情况下同时会生成
scopedTarget.beanName
的 bean
- 使用 @RefreshScope 注解的 bean,默认情况下同时会生成
@Autowired
private ApplicationContext context;
@Test
public void testRabbitTemplate() {
String[] beanNames = context.getBeanNamesForType(ConnectionFactory.class);
for (String beanName : beanNames) {
System.out.println(beanName);
}
Assert.isTrue(beanNames.length == 2);
}
scopedTarget.connectionFactory
connectionFactory
-
- 由于 ConditionalOnSingleCandidate 成立的条件是全局只能有一个此类型的 bean 所以 默认的 RabbitTemplate 无法注入
常见被 ConditionalOnSingleCandidate 注解的 bean
-
- 使用 JdbcTemplate 无法在自定义 DataSource 添加 @RefreshScope
@ConditionalOnSingleCandidate(DataSource.class)
public class JdbcTemplateAutoConfiguration {}
-
- MailSenderValidator 邮件发送校验器无法添加 @RefreshScope
@Configuration(proxyBeanMethods = false)
@AutoConfigureAfter(MailSenderAutoConfiguration.class)
@ConditionalOnProperty(prefix = "spring.mail", value = "test-connection")
@ConditionalOnSingleCandidate(JavaMailSenderImpl.class)
public class MailSenderValidatorAutoConfiguration {}
-
- 由于默认情况下涉及的 bean 很多,所以使用 RefreshScope 时一定要避免这些 bean
- 配套源码: https://github.com/lltx/spring-boot-course/tree/master/v2.3/refresh-scope-bug
项目推荐: Spring Cloud 、Spring Security OAuth2的RBAC权限管理系统 欢迎关注