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This article shows you how to parse the usage of the SpringCloud @ FeignClient parameter, which is concise and easy to understand, which will definitely brighten your eyes. I hope you can get something from the detailed introduction of this article.

Detailed explanation of SpringCloud @ FeignClient parameters

Today, because I came across a strange bug from FeignClient at work, I studied it carefully and found out the reason, so I just want to sum up the note FeignClient:

First look at the @ FeignClient source code: the source code is as follows, at the end of this article.

There are 11 methods, and the common methods are described as follows

@ FeignClient (name = "service-name", url = "${feign.urls.service-name:}", fallback = ApiFallBack.class,configuration = Interceptor.class)

1. Valuegravity name has the same meaning: it corresponds to the service name of the invoked micro-service, which is critical to service discovery and gateway invocation.

2.url this is the access address, which can be provided directly to external calls or written directly, such as 192.168.1.11:8800/applicationName

3.fallback and fallbackFactory

Set the fallback property to the @ FeignClient annotation, and the fallback class inherits the interface annotated by @ FeignClient

If the ApiFallBack class is taken out as a separate class, we have to add the annotation @ Component to the class

If the default priority of fallback is higher than the priority of fallfactory. So if both exist, you will access the fallback method of fallback.

There is no demonstration here.

So what's the difference between fallback and fallfactory?

@ FeignClient (name = "service-name", fallbackFactory = HystrixClientFallbackFactory.class) protected interface HystrixClient {@ RequestMapping (method = RequestMethod.GET, value = "/ test") Hello iFailSometimes ();} @ Componentstatic class HystrixClientFallbackFactory implements FallbackFactory {@ Overridepublic HystrixClient create (Throwable cause) {return new HystrixClientWithFallBackFactory () {@ Overridepublic Hello iFailSometimes () {return new Hello ("fallback; reason was:" + cause.getMessage ());};}}

The difference between fallback and fallfactory

Fallback simply overrides the fallback method.

The fallfactory layer is deeper because it throws an exception with a thread, and you can see the underlying specific problems.

/ * * 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 @ RibbonClient 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 @ Qualifier 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 @ Configuration for the feign client. Can contain override * @ Bean 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 bea 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 bea 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 * @ RibbonClient. * / String path () default ""; / * * Whether to mark the feign proxy as a primary bean. Defaults to true. * / boolean primary () default true;} @ FeignClient Annotation Common parameters

For fear of forgetting later, summarize the parameters in the @ FeignClient annotation actually used in the project, as follows:

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 is equivalent to name.

Url

Generally used for debugging, you can manually specify the address of the @ FeignClient call

The above is how to parse the use of the SpringCloud @ FeignClient parameter. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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