@Feignclient detailed tutorial (illustration)

effect

@FeignClient Used to create a declaration yes API Interface , The interface is RESTful Style .Feign Designed to be pluggable , Other components and Feign Use it together . The most typical is if Ribbon You can use ,Feign Hui He Ribbon Combining load balancing .

@FeignClient Common properties of tags

• Source screenshot
  
• name（ and value identical ）： Appoint FeignClient The name of , If the project is used Ribbon,name Attributes will be used as microservices （ The name of a center ） The name of , For service discovery ( The diagram is as follows )
• url: url Generally used for debugging , Can be specified manually @FeignClient The address of the call ( The diagram is as follows )
• decode404（） namely 404 Is decoded , Or throw an exception .
• configuration（） To specify FeignClient Configuration class , The default configuration class is FeignClientsConfiguration class , By default , This class injects the default Decoder、Encoder and Constant And so on bean.
• fallback() Configure the processing class of fuse .
  
  
• FeignClient Configuration class （configuration（））

public class FeignUserSupportConfig
{
    
    @Bean
    @Primary
    @Scope("prototype")
    public Encoder multipartFormEncoder() {
    
        return new SpringFormEncoder(new SpringEncoder(new ObjectFactory<HttpMessageConverters>() {
    
            @Override
            public HttpMessageConverters getObject() throws BeansException
            {
    
                return new HttpMessageConverters(new RestTemplate().getMessageConverters());
            }
        }));
    }

    @Bean
    public feign.Logger.Level multipartLoggerLevel() {
    
        return feign.Logger.Level.FULL;
    }
}

Usage flow

• 1. Add... In the startup class @EnableFeignClients
  
• 2. Defining interfaces

package com.xxx.xxx.client;


import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

import java.util.Map;

@Component
/** * value = "user"  in  user  by   call  user  Service Id * spring.application.name=user */
@FeignClient(value = "user", configuration = UserSupportConfig.class)
public interface TestClientService {
    
    /** * @param id * @return /user/selectById  by  userController  Medium  /user/selectById  Method address  */
    @RequestMapping(value = "/user/selectById", method = RequestMethod.GET, produces = {
    MediaType.APPLICATION_JSON_UTF8_VALUE}, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    /** * userId  Is the parameter   Must write @RequestParam  Otherwise, the report will be wrong  */
    Map upload(@RequestParam("userId") Integer id);
}

• 3. Define fuse class , Callback when an error occurs ：

import java.util.List;
import org.springframework.stereotype.Component;
@Component
public class Hysitx implements TestClientService {
    
	@Override
	public List<String> test(String[] names) {
    
		System.out.println(" Interface call failed ");
		return null;
	}
}

• 4. call
  And basic service Call consistency
  1. First introduced @Autowired
  2. Call directly in the method

Popular explanation can regard it as a spring Bean It can be directly regarded as a Service

to @FeignClient add to Header Information

1. stay @RequestMapping Add

@FeignClient(name="custorm",fallback=Hysitx.class)
public interface IRemoteCallService {
    
	@RequestMapping(value="/user/selectById",method = RequestMethod.POST,
		headers = {
    "Content-Type=application/json;charset=UTF-8"})
    Map test(@RequestParam("userId") int id);
}

2. Add the parameter before the method @RequestHeader annotation ：

@FeignClient(name="custorm",fallback=Hysitx.class)
public interface IRemoteCallService {
    
	@RequestMapping(value="/user/selectById",method = RequestMethod.POST,
		headers = {
    "Content-Type=application/json;charset=UTF-8"})
    List<String> test(@RequestParam("userId")@RequestHeader("Authorization") int id);
}

3. Use @Header annotation

@FeignClient(name="custorm",fallback=Hysitx.class)
public interface IRemoteCallService {
    
	@RequestMapping(value="/user/selectById",method = RequestMethod.POST)
	@Headers({
    "Content-Type: application/json;charset=UTF-8"})
    List<String> test(@RequestParam("userId") int id);
}