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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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。 -
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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 -
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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(); }@Componentstatic class HystrixClientFallbackFactory implements FallbackFactory<HystrixClient> {@Overridepublic HystrixClient create(Throwable cause) {return new HystrixClientWithFallBackFactory() {@Overridepublic Hello iFailSometimes() {return new Hello("fallback; reason was: " + cause.getMessage());}};}} |
fallback和fallfactory区别
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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)@Documentedpublic @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; } |
@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);} |
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
