初探Spring Cloud Fegin （简单使用）
Fegin是一个声明式的web service 客户端。使用Fegin只需要在接口上加上注解就好了，方便快捷。Feign具有可插拔的注解特性，包括Feign 注解和JAX-RS注解，同时增加了对 Spring MVC的注解，Spring Web 默认使用了HttpMessageConverters, Spring Cloud 集成 Ribbon 和 Eureka 提供的负载均衡的HTTP客户端 Feign。在Spring Cloud中使用Fegin，就像调用本地方法一样，开发者完全感受不到这是在调用远程方法。
eureka-fegin、eureka-fegin-service和eureka-fegin-service-tmp 三个服务
eureka-fegin 通过fegin 调用eureka-fegin-service和eureka-fegin-service-tmp提供的服务
eureka-fegin-service和eureka-fegin-service-tmp的配置文件application.yml（服务端口记得不能一样）
server:
port: 8070
eureka:
client:
service-url:
defaultZone: http://localhost:8080/eureka/
spring:
application:
name: eureka-fegin-service提供服务的接口：
package com.cn.controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class FeginServiceController {
@RequestMapping("/getName")
public String getName(@RequestParam String name){
return "hello1 : " + name;
}
}
依赖：
dependencies {
compile('org.springframework.cloud:spring-cloud-starter-netflix-eureka-client')
}启动类：
package com.cn;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@EnableEurekaClient
@SpringBootApplication
public class FeginServiceApplication {
public static void main(String[] args) {
SpringApplication.run(FeginServiceApplication.class, args);
}
}
eureka-fegin的配置文件application.yml
server:
port: 8088
eureka:
client:
service-url:
defaultZone: http://localhost:8080/eureka/
spring:
application:
name: eureka-feginFeginService接口：
package com.cn.service;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
@FeignClient(value = "eureka-fegin-service")
public interface FeginService {
@RequestMapping(value = "/getName", method = RequestMethod.GET)
public String getName(@RequestParam("name") String name);
}
PS:记得添加FeginClient注解，value值为需要调用的服务（eureka-fegin-service和eureka-fegin-service-tmp的配置文件application.yml中配置的spring.application.name=eureka-fegin-service）的应用名称。
package com.cn.controller;
import com.cn.service.FeginService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class FeginController {
@Autowired
private FeginService feginService;
@RequestMapping(value = "/getName")
public String search(@RequestParam("name") String name){
return feginService.getName(name);
}
}
启动类：
package com.cn;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class FeginApplication {
public static void main(String[] args) {
SpringApplication.run(FeginApplication.class, args);
}
}
下面两个注解一定不要忘记添加 EnableFeignClients:开启Fegin的使用 EnableDiscoveryClient:开启服务发现
访问：http://localhost:8070/getName?name=bob
页面输出：hello1 : bob
访问：http://localhost:8060/getName?name=bob
页面输出：hello2 : bob
访问：http://localhost:8088/getName?name=bob
页面会循环输出：hello1 : bob和hello2 : bob