SpringCloud Feign 全局Fallback的另一种实现方式（SpringBoot3.4+）
文章目录
- 前言
- 一、定制Fegin
- 二、定制断路器
- 1.自定义断路器DefaultCircuitBreaker
- 2.定义Resilience4JCircuitBreakerFactory bean来替换内置断路器
- 封装成Starter
前言
之前在SpringBoot2.7+中实现 全局Fallback方式较为复杂，且是从Feign入手，现在从断路器入手，通过捕获异常方式实现。
注意：这里基于SpringBoot3.4实现的，如果是2.7那么又会复杂一点，原因是内置的Resilience4JCircuitBreakerFactory实现的接口未返回接口CircuitBreaker而是实现Resilience4JCircuitBreaker，在3.4版本已修正为接口CircuitBreaker。
一、定制Fegin
请参考之前的实现。
二、定制断路器
因为在未设置断路器时，会抛出NoFallbackAvailableException，所以就通过捕获NoFallbackAvailableException来实现全局Fallback
1.自定义断路器DefaultCircuitBreaker
class DefaultCircuitBreaker implements CircuitBreaker {
private static final Logger log = LoggerFactory.getLogger(DefaultCircuitBreaker.class);
private final CircuitBreaker circuitBreaker;
DefaultCircuitBreaker(CircuitBreaker circuitBreaker) {
this.circuitBreaker = circuitBreaker;
}
@SuppressWarnings("unchecked")
@Override
public <T> T run(Supplier<T> toRun, Function<Throwable, T> fallback) {
try {
return circuitBreaker.run(toRun, fallback);
} catch (NoFallbackAvailableException e) {
Throwable cause = e.getCause();
String errorMessage = cause.getMessage();
if (cause instanceof FeignException exception && !exception.contentUTF8().isEmpty()) {
errorMessage = exception.contentUTF8();
}
log.error("Using DefaultFallback handle exception", cause);
return (T) RestResp.error(ExceptionKeys.REMOTE_SERVICE_ERROR, errorMessage);
}
}
}
2.定义Resilience4JCircuitBreakerFactory bean来替换内置断路器
@Bean
Resilience4JCircuitBreakerFactory resilience4jCircuitBreakerFactory(CircuitBreakerRegistry circuitBreakerRegistry, TimeLimiterRegistry timeLimiterRegistry,
@Autowired(required = false) Resilience4jBulkheadProvider bulkheadProvider,
Resilience4JConfigurationProperties resilience4JConfigurationProperties) {
return new Resilience4JCircuitBreakerFactory(circuitBreakerRegistry,
timeLimiterRegistry, bulkheadProvider, resilience4JConfigurationProperties) {
@Override
public CircuitBreaker create(String id) {
return new DefaultCircuitBreaker(super.create(id));
}
@Override
public CircuitBreaker create(String id, String groupName) {
return new DefaultCircuitBreaker(super.create(id, groupName));
}
};
}
封装成Starter
- 创建一个自动配置类CircuitBreakerAutoConfiguration
@AutoConfiguration(before = Resilience4JAutoConfiguration.class)
@ConditionalOnClass(Resilience4JCircuitBreakerFactory.class)
public class CircuitBreakerAutoConfiguration {
@Bean
Resilience4JCircuitBreakerFactory resilience4jCircuitBreakerFactory(CircuitBreakerRegistry circuitBreakerRegistry, TimeLimiterRegistry timeLimiterRegistry,
@Autowired(required = false) Resilience4jBulkheadProvider bulkheadProvider,
Resilience4JConfigurationProperties resilience4JConfigurationProperties) {
return new Resilience4JCircuitBreakerFactory(circuitBreakerRegistry,
timeLimiterRegistry, bulkheadProvider, resilience4JConfigurationProperties) {
@Override
public CircuitBreaker create(String id) {
return new DefaultCircuitBreaker(super.create(id));
}
@Override
public CircuitBreaker create(String id, String groupName) {
return new DefaultCircuitBreaker(super.create(id, groupName));
}
};
}
}
-
将配置类添加到配置文件org.springframework.boot.autoconfigure.AutoConfiguration.imports中
-
如果需要配置一个开关来启用CircuitBreakerAutoConfiguration，也可以添加条件注解ConditionalOnProperty如下
@ConditionalOnProperty(prefix = "mcn.circuitbreaker", name = "default.enabled", havingValue = "true", matchIfMissing = true)