java健康检查的作用,详解SpringBoot健康检查的实现原理
SpringBoot自动装配的套路，直接看 spring.factories文件，当我们使用的时候只需要引入如下依赖
org.springframework.boot
spring-boot-starter-actuator
然后在 org.springframework.boot.spring-boot-actuator-autoconfigure包下去就可以找到这个文件
自动装配
查看这个文件发现引入了很多的配置类，这里先关注一下 XXXHealthIndicatorAutoConfiguration 系列的类，这里咱们拿第一个 RabbitHealthIndicatorAutoConfiguration 为例来解析一下。看名字就知道这个是RabbitMQ的健康检查的自动配置类
@Configuration
@ConditionalOnClass(RabbitTemplate.class)
@ConditionalOnBean(RabbitTemplate.class)
@ConditionalOnEnabledHealthIndicator("rabbit")
@AutoConfigureBefore(HealthIndicatorAutoConfiguration.class)
@AutoConfigureAfter(RabbitAutoConfiguration.class)
public class RabbitHealthIndicatorAutoConfiguration extends
CompositeHealthIndicatorConfiguration {
private final Map rabbitTemplates;
public RabbitHealthIndicatorAutoConfiguration(
Map rabbitTemplates) {
this.rabbitTemplates = rabbitTemplates;
}
@Bean
@ConditionalOnMissingBean(name = "rabbitHealthIndicator")
public HealthIndicator rabbitHealthIndicator() {
return createHealthIndicator(this.rabbitTemplates);
}
}
按照以往的惯例，先解析注解
@ConditionalOnXXX 系列又出现了，前两个就是说如果当前存在 RabbitTemplate 这个bean也就是说我们的项目中使用到了RabbitMQ才能进行下去
@ConditionalOnEnabledHealthIndicator 这个注解很明显是SpringBoot actuator自定义的注解，看一下吧
@Conditional(OnEnabledHealthIndicatorCondition.class)
public @interface ConditionalOnEnabledHealthIndicator {
String value();
}
class OnEnabledHealthIndicatorCondition extends OnEndpointElementCondition {
OnEnabledHealthIndicatorCondition() {
super("management.health.", ConditionalOnEnabledHealthIndicator.class);
}
}
public abstract class OnEndpointElementCondition extends SpringBootCondition {
private final String prefix;
private final Class extends Annotation> annotationType;
protected OnEndpointElementCondition(String prefix,
Class extends Annotation> annotationType) {
this.prefix = prefix;
this.annotationType = annotationType;
}
@Override
public ConditionOutcome getMatchOutcome(ConditionContext context,
AnnotatedTypeMetadata metadata) {
AnnotationAttributes annotationAttributes = AnnotationAttributes
.fromMap(metadata.getAnnotationAttributes(this.annotationType.getName()));
String endpointName = annotationAttributes.getString("value");
ConditionOutcome outcome = getEndpointOutcome