Automatic assembly and fuse degradation of feign

Use steps

The first step is to import feign rely on

  <!-- Spring Cloud  Microservice load balancing  -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

        <!-- Spring Cloud  Microservice remote call  -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

   <!--sentinel-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>

The second step is to configure feign

#  Turn on  feign  The remote call of uses fusing 
feign.sentinel.enabled = true
#  Configuration request GZIP Compress 
feign.compression.request.enabled = true
#  Configure the minimum compressed data size 
feign.compression.request.min-request-size = 2048
#  Configure response GZIP Compress 
feign.compression.response.enabled = true
#  Configure compression support MIME TYPE
feign.compression.request.mime-types[0] = text/xml
feign.compression.request.mime-types[1] = application/xml
feign.compression.request.mime-types[2] = application/json


#     Below is the setting feign Call yes, timeout, etc , Prevent avalanche 
# Number of retries to the current instance  default 0
ribbon.MaxAutoRetries = 1
# Set connection timeout  default 2000
ribbon.ConnectTimeout = 3000
# Retry all operation requests  default false
ribbon.OkToRetryOnAllOperations = false
# Set read timeout  default 5000
ribbon.ReadTimeout = 20000
# Number of retries to switch instances  default 1
ribbon.MaxAutoRetriesNextServer = 1

  The third step ( utilize spring Of SPI)： stay resource Created in META-INF, also META-INF Created in spring.factories

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.xuecheng.api.feign.config.FeignConfig

  My waiting right points to mine feign Configuration class , such Spring When it starts , I will scan first resource.META-INF.spring.factories file , Scan the files pointed to inside ,

@Configuration
@ComponentScan(basePackages = {"com.xuecheng.api.feign"})    // This is to scan the path and add IOC Class in 
@EnableFeignClients(basePackages = {"com.xuecheng.api.feign"})  // This is used to scan the path feign Give the annotated package to ioc management 
public class FeignConfig {
}

such spring Will be based on spring.factories Found the path specified in FeignConfig, By scanning FeignConfig See there are

@EnableFeignClients(basePackages = {"com.xuecheng.api.feign"})  // This is used to scan the path feign Give the annotated package to ioc management 

annotation , Will scan com.xuecheng.api.feign Under the use of Feign Related annotation class .

But if fuse is configured , But fusing is not used feign Relevant comments, so the above @EnableFeignClients It will not scan the package that is not used feign Related notes , Then you need to be in FeignConfig Add annotation to

@ComponentScan(basePackages = {"com.xuecheng.api.feign"}) // This is to scan the path and add IOC Class in 

Put all under this path   @Componen    Derived needs to be connected to IOC The class of the container is handed over to Spring management , And the fuse class is just under this path , That's it Feign Automatic assembly of

technological process ：Spring start-up   -------->      Scan all in the project  resource.META-INF.spring.factories Content ------> Find the specified FeignConfig class --------------->    adopt FeignConfig Annotations configured in @EnableFeignClients scanning feignj All uses under the package where the interface is located Feign Related annotation class , Add to IOC in ------------>  If there is a fuse , adopt @ComponentScan Scan under the package where the fuse class is located All use @Componen    And classes derived from annotations are added to IOC in .

So that's the end of it feign Integrated into the Spring in