SpringCloud微服务实战之Feign

女爷i 2022-06-03 06:41 308阅读 0赞

> Spring Cloud Feign基于Netflix Feign实现，整合了Spring Cloud Ribbon和Spring Cloud Hystrix，它除了提供这两者的强大功能之外，还提供了一种声明式的web服务客户端定义方式。

一、使用Feign实现HelloService服务消费  
1、创建Maven项目SpringCloud-Feign，目录结构如下  
![这里写图片描述][SouthEast]

2、pom中添加feign依赖

<dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </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>
        </dependencies>

3、在主类中添加注解@EnableFeignClients开启对Feign的支持。  
4、定义HelloService接口，通过@FeignClient注解来绑定HelloService服务，name代表服务名，fallback代表Hystrix熔断器服务降级处理逻辑类。实现UserService接口同理。

package com.spring.springcloud.service;
    
    import org.springframework.cloud.netflix.feign.FeignClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    import com.spring.springcloud.service.fb.HelloServiceFallback;
    
    @FeignClient(name="helloservice",fallback=HelloServiceFallback.class)
    public interface HelloService {
    
        @RequestMapping("/hello")
        public String hello();
    }

package com.spring.springcloud.service.fb;
    
    import org.springframework.stereotype.Component;
    
    import com.spring.springcloud.service.HelloService;
    
    @Component
    public class HelloServiceFallback implements HelloService { 
    
        @Override
        public String hello() {
            return "Error";
        }
    
    }

--------------------

package com.spring.springcloud.service;
    
    import org.springframework.cloud.netflix.feign.FeignClient;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestBody;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    
    import com.spring.springcloud.service.fb.UserServiceFallback;
    import com.spring.springcloud.vo.User;
    
    @FeignClient(name="helloservice",fallback=UserServiceFallback.class)
    public interface UserService {
    
        @RequestMapping(value="/findUser/{id}",method=RequestMethod.GET)
        public User findUserById(@PathVariable("id") Long id);
    
        @RequestMapping(value="/addUser",method=RequestMethod.POST)
        public User addUser(@RequestBody User user);
    }

package com.spring.springcloud.service.fb;
    
    import org.springframework.stereotype.Component;
    
    import com.spring.springcloud.service.UserService;
    import com.spring.springcloud.vo.User;
    
    @Component
    public class UserServiceFallback implements UserService { 
    
        @Override
        public User findUserById(Long id) {
            User user = new User();
            user.setId(new Long(5555));
            user.setUserName("defalutConsumerForFind");
            return null;
        }
    
        @Override
        public User addUser(User user) {
            user.setId(new Long(6666));
            user.setUserName("defalutConsumerForAdd");
            return null;
        }
    
    }

5、增加application.properties

server.port=8666
    
    spring.application.name=feignconsumer
    eureka.client.serviceUrl.defaultZone=http://localhost:8888/eureka/

测试：

*  访问helloService的hello接口  
    ![这里写图片描述][SouthEast 1]  
    模拟阻塞，调用fallback方法  
    ![这里写图片描述][SouthEast 2]
 *  访问helloservice的user相关接口  
    ![这里写图片描述][SouthEast 3]

[SouthEast]: /images/20220603/5eb4b042ba114d769c81946bf387db9b.png
[SouthEast 1]: /images/20220603/0033a1787dc6473fb2dac91d27251352.png
[SouthEast 2]: /images/20220603/437303aae55e4301842236761dd5d645.png
[SouthEast 3]: /images/20220603/e95b7bf52af9458cb248e62b12c900ce.png