序
feign默认集成了hystrix,那么问题来了,如何像hystrix command那样设置每个方法的hystrix属性呢。
实例
@FeignClient("product")
public interface RemoteProductService {
@RequestMapping(method = RequestMethod.GET,value = "/product/{productId}")
public Product getProduct(@PathVariable(value = "productId") int productId);
}
FeignClientsConfiguration
spring-cloud-netflix-core-1.2.6.RELEASE-sources.jar!/org/springframework/cloud/netflix/feign/FeignClientsConfiguration.java
@Configuration
@ConditionalOnClass({ HystrixCommand.class, HystrixFeign.class })
protected static class HystrixFeignConfiguration {
@Bean
@Scope("prototype")
@ConditionalOnMissingBean
@ConditionalOnProperty(name = "feign.hystrix.enabled", matchIfMissing = true)
public Feign.Builder feignHystrixBuilder() {
return HystrixFeign.builder();
}
}
HystrixFeign
feign-hystrix-9.3.1-sources.jar!/feign/hystrix/HystrixFeign.java
private SetterFactory setterFactory = new SetterFactory.Default();
SetterFactory
feign-hystrix-9.3.1-sources.jar!/feign/hystrix/SetterFactory.java
public interface SetterFactory {
/**
* Returns a hystrix setter appropriate for the given target and method
*/
HystrixCommand.Setter create(Target<?> target, Method method);
/**
* Default behavior is to derive the group key from {@link Target#name()} and the command key from
* {@link Feign#configKey(Class, Method)}.
*/
final class Default implements SetterFactory {
@Override
public HystrixCommand.Setter create(Target<?> target, Method method) {
String groupKey = target.name();
String commandKey = Feign.configKey(target.type(), method);
return HystrixCommand.Setter
.withGroupKey(HystrixCommandGroupKey.Factory.asKey(groupKey))
.andCommandKey(HystrixCommandKey.Factory.asKey(commandKey));
}
}
}
groupKey,这里为product,即@FeignClient("product")中的值。
Feign.configKey
feign-core-9.3.1-sources.jar!/feign/Feign.java
public static String configKey(Class targetType, Method method) {
StringBuilder builder = new StringBuilder();
builder.append(targetType.getSimpleName());
builder.append('#').append(method.getName()).append('(');
for (Type param : method.getGenericParameterTypes()) {
param = Types.resolve(targetType, targetType, param);
builder.append(Types.getRawType(param).getSimpleName()).append(',');
}
if (method.getParameterTypes().length > 0) {
builder.deleteCharAt(builder.length() - 1);
}
return builder.append(')').toString();
}
commandKey的构造,这里组装了类、方法名、参数,比如本文的实例,commandKey=RemoteProductService#getProduct(int)
配置文件指定
hystrix:
command:
"RemoteProductService#getProduct(int)":
execution:
isolation:
thread:
timeoutInMilliseconds: 500
Java中指定
@Bean
public Feign.Builder feignHystrixBuilder() {
return HystrixFeign.builder().setterFactory(new SetterFactory() {
@Override
public HystrixCommand.Setter create(Target<?> target, Method method) {
return HystrixCommand.Setter
.withGroupKey(HystrixCommandGroupKey.Factory.asKey(RemoteProductService.class.getSimpleName()))// 控制 RemoteProductService 下,所有方法的Hystrix Configuration
.andCommandPropertiesDefaults(
HystrixCommandProperties.Setter().withExecutionTimeoutInMilliseconds(10000) // 超时配置
);
}
});
}
小结
论灵活程度,还是配置文件灵活一点,唯一的工作量就是根据规则构造commandKey,然后就可以进行相关配置了。
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