SpringCloud (D): Consumer Services (Feign)

A, Feign introduce
Feign is a pseudo Http client a declarative, it makes writing easier Http client. Using Feign, only you need to create an interface and annotation. It has pluggable annotation feature can be used Feign JAX-RS annotations and notes. Feign pluggable encoder and decoder. Feign default integrated Ribbon, and Eureka and combined, the default implementation of load balancing.

Two, Feign consumer services:

pom.xml:

　　　　<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>

application.properties：

spring.application.name=hello-consumer-feign
server.port=8031
eureka.client.serviceUrl.defaultZone=http://localhost:8001/eureka/

Feign client: Package Penalty for cn.demo.service;

Import org.springframework.cloud.netflix.feign.FeignClient;
 Import org.springframework.web.bind.annotation.RequestMapping;
 Import org.springframework.web.bind.annotation.RequestParam;
 
// NOTE point: Case where user-service can, by default will be transferred to uppercase 
@FeignClient ( "the User-Service" )
 public  interface the HelloService {
　　
// here must be configured such that, if not configured or configured value = name1 or other value, equivalent to pass other key parameters in the past here pass wrong, it will return hello, null, because the value of hello-service interface to get the name. 
    @RequestMapping ( "Hello" ) 
    String Hello (@RequestParam (value = "name" ) String name); 
}

Start categories:

package cn.demo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import cn.demo.service.HelloService;

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@RestController
public class HelloConsumerFeignApplication {

    public static void main(String[] args) {
        SpringApplication.run(HelloConsumerFeignApplication.class, args);
    }


    @Autowired
    private HelloService helloService;

    @RequestMapping("hello")
    public String hello(String name){
        return helloService.hello(name);
    }
}

Third, the test

Similarly, the first start eureka-server: 8001, and hello-service: 8011,8012, then visit:

http://localhost:8031/hello?name=feign

result:

 

 The same number of visits, hello-service: 8011, 8012 print call log has information indicating also realizes load balancing.