feign特点
和ribbon一样feign也可以作微服务的负载均衡，使用feign来调用的api接口让api接口更像是本地的接口
源代码
yaml 配置
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
server:
port: 8765
spring:
application:
name: service-feign
feign.hystrix.enabled: true
pom 配置
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.example</groupId>
<artifactId>spring-cloud-eureka-master</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>spring-cloud-eureka-feign</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
</dependencies>
</project>
java 代码如下
/**
*
* 一个服务注册中心，eureka server,端口为8761 service-hi工程跑了两个实例，端口分别为8762,8763，分别向服务注册中心注册
* sercvice-ribbon端口为8764,向服务注册中心注册
* 当sercvice-ribbon通过restTemplate调用EURKA-CLIENT的hi接口时，
* 因为用ribbon进行了负载均衡，会轮流的调用EURKA-CLIENT：8762和8763 两个端口的hi接口；
*/
// feign 自带了hystrix ，只需要开启hystrix功能就可以了：feign.hystrix.enabled=true
@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
@EnableFeignClients
public class ServiceFeignApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceFeignApplication.class, args);
}
@Bean
@LoadBalanced
RestTemplate restTemplate() {
return new RestTemplate();
}
}
/**
* 通过feign 获取eurka-client服务提供的api接口
*/
@FeignClient(value = "eurka-client",fallback = SchedualServiceHiHystric.class)
public interface ScheduleService {
@RequestMapping(value = "/hi", method = RequestMethod.GET)
String sayHi(@RequestParam(value = "name") String name);
}
@Component
public class SchedualServiceHiHystric implements ScheduleService {
@Override
public String sayHi(String name) {
return "sorry "+name;
}
}
@RestController
public class HelloControler {
// 编译器报错，无视。 因为这个Bean是在程序启动的时候注入的，编译器感知不到，所以报错。
@Autowired
ScheduleService schedualService;
@GetMapping(value = "/hi")
public String sayHi(@RequestParam String name) {
return schedualService.sayHi(name);
}
}