SpringCloud @FeignClient 参数详解
今天因为工作中遇到FeignClient一个奇葩的bug，后面仔细研究了，找出了原因，那么刚好对FeignClient 这个注解总结一下：
先看@FeignClient 源码：源码如下，本文最后面。
11个方法，常用方法说明如下
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@FeignClient(name = "service-name", url = "${feign.urls.service-name:}", fallback =ApiFallBack.class,configuration = Interceptor.class)
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-
1.
value,name这两个就同一个意思：对应的是调用的微服务的服务名，对用服务发现、走网关调用，这个很关键。 -
2.
url这是访问地址，可以直接提供给外部调用，也可以直接写如192.168.1.11:8800/applicationName -
3.
fallback与fallbackFactory
就给@FeignClient注解设置fallback属性，并且回退类要继承@FeignClient所注解的接口
ApiFallBack类拿出去单独作为一个类的话，我们就得在该类上添加注解@Component
如果fallback默认优先级比fallfactory优先级高。所以二者都存在的话，会访问fallback的回退方法。
这里不做演示。
那么fallback和fallfactory有什么区别呢
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@FeignClient(name = "service-name", fallbackFactory = HystrixClientFallbackFactory.class)
protected interface HystrixClient {
@RequestMapping(method = RequestMethod.GET, value = "/test")
Hello iFailSometimes();
}
@Component
static class HystrixClientFallbackFactory implements FallbackFactory<HystrixClient> {
@Override
public HystrixClient create(Throwable cause) {
return new HystrixClientWithFallBackFactory() {
@Override
public Hello iFailSometimes() {
return new Hello("fallback; reason was: " + cause.getMessage());
}
};
}
}
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fallback和fallfactory区别
-
fallback只是重写了回退方法。 -
fallfactory层面比较深，因为它用线程抛出了异常,可以看到底层具体问题。
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/**
* Annotation for interfaces declaring that a REST client with that interface should be
* created (e.g. for autowiring into another component). If ribbon is available it will be
* used to load balance the backend requests, and the load balancer can be configured
* using a <code>@RibbonClient</code> with the same name (i.e. value) as the feign client.
*
* @author Spencer Gibb
* @author Venil Noronha
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface FeignClient {
/**
* The name of the service with optional protocol prefix. Synonym for {@link #name()
* name}. A name must be specified for all clients, whether or not a url is provided.
* Can be specified as property key, eg: ${propertyKey}.
*/
@AliasFor("name")
String value() default "";
/**
* The service id with optional protocol prefix. Synonym for {@link #value() value}.
*
* @deprecated use {@link #name() name} instead
*/
@Deprecated
String serviceId() default "";
/**
* The service id with optional protocol prefix. Synonym for {@link #value() value}.
*/
@AliasFor("value")
String name() default "";
/**
* Sets the <code>@Qualifier</code> value for the feign client.
*/
String qualifier() default "";
/**
* An absolute URL or resolvable hostname (the protocol is optional).
*/
String url() default "";
/**
* Whether 404s should be decoded instead of throwing FeignExceptions
*/
boolean decode404() default false;
/**
* A custom <code>@Configuration</code> for the feign client. Can contain override
* <code>@Bean</code> definition for the pieces that make up the client, for instance
* {@link feign.codec.Decoder}, {@link feign.codec.Encoder}, {@link feign.Contract}.
*
* @see FeignClientsConfiguration for the defaults
*/
Class<?>[] configuration() default {};
/**
* Fallback class for the specified Feign client interface. The fallback class must
* implement the interface annotated by this annotation and be a valid spring bean.
*/
Class<?> fallback() default void.class;
/**
* Define a fallback factory for the specified Feign client interface. The fallback
* factory must produce instances of fallback classes that implement the interface
* annotated by {@link FeignClient}. The fallback factory must be a valid spring
* bean.
*
* @see feign.hystrix.FallbackFactory for details.
*/
Class<?> fallbackFactory() default void.class;
/**
* Path prefix to be used by all method-level mappings. Can be used with or without
* <code>@RibbonClient</code>.
*/
String path() default "";
/**
* Whether to mark the feign proxy as a primary bean. Defaults to true.
*/
boolean primary() default true;
}
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@FeignClient 注解常用参数
怕以后又忘记，总结下目前项目中实际用到的 @FeignClient 注解中的参数，如下：
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@FeignClient(value = "annoroad-alpha", url = "${annoroad.ms.annoroad-alpha.url}")
public interface UserFacade {
@PostMapping(value = "/user/detail")
UserDto detail(@RequestParam("id") long id);
}
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value
- value 等同于 name
url
- 一般用于调试，可以手动指定 @FeignClient 调用的地址
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/Susan8888/article/details/95992172