Spring Cloud 学习 (三) Feign

我就是我 2021-12-21 04:43 219阅读 0赞

新建 spring-cloud-eureka-feign-client Module

# pom #

<parent>
        <artifactId>spring-cloud-parent</artifactId>
        <groupId>com.karonda</groupId>
        <version>1.0.0</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    
    <artifactId>spring-cloud-eureka-feign-client</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>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

# application.yml #

server:
      port: 8031
    
    eureka:
      client:
        service-url:
          defaultZone: http://localhost:8001/eureka/
    
    spring:
      application:
        name: feign-client

# 启动类 #

@EnableFeignClients // 开启 Feign Client
    @EnableEurekaClient
    @SpringBootApplication
    public class EurekaFeignClientApp {
        public static void main(String[] args){
            SpringApplication.run(EurekaFeignClientApp.class, args);
        }
    }

# FeignClient #

@FeignClient("eureka-client")
    public interface EurekaClientFeign {
    
        @GetMapping("/hi")
        String sayHi(@RequestParam(value = "name") String name);
    }

# Controller #

@RestController
    public class FeignController {
    
        @Autowired
        EurekaClientFeign eurekaClientFeign;
    
        @GetMapping("/hi")
        public String sayHi(@RequestParam String name){
            return eurekaClientFeign.sayHi(name);
        }
    }

# 测试 #

1.  启动 eureka-server
2.  启动 eureka-client (两个实例：一个 8011 端口，一个 8012 端口)
3.  启动 eureka-feign-client

多次访问 [http://localhost:8031/hi?name=victor][http_localhost_8031_hi_name_victor] 可以看到 8011 和 8012 端口交替出现

# 添加失败重试 #

## 添加配置 ##

@Configuration
    public class FeignConfig {
    
        @Bean
        public Retryer feignRetryer(){
            return new Retryer.Default(100, SECONDS.toMillis(1), 5);
        }
    }

## 修改 FeignClient ##

@FeignClient(value = "eureka-client", configuration = FeignConfig.class)
    public interface EurekaClientFeign {
    
        @GetMapping("/hi")
        String sayHi(@RequestParam(value = "name") String name);
    }

# 使用 HttpClient 或 OkHttp #

在 Feign 中，Client 是一个非常重要的组件，Feign 最终发送 Request 请求以及接收 Response 响应都是由 Client 组件完成的。Client 在 Feign 源码中是一个接口，在默认的情况下， Client 的实现类是 Client.Default, Client.Default 是由 HttpURLConnnection 来实现网络请求的。Client 还支持 HttpClient 和 OkhHttp 来进行网络请求

直接添加 HttpClient 或 OkhHttp 依赖包，Feign 会自动使用对应的网络请求框架

完整代码：[GitHub][]

**本人 C\# 转 Java 的 newbie, 如有错误或不足欢迎指正，谢谢**

转载于:https://www.cnblogs.com/victorbu/p/11008396.html

[http_localhost_8031_hi_name_victor]: http://localhost:8031/hi?name=victor
[GitHub]: https://github.com/VictorBu/code-snippet/tree/master/java/spring-cloud-parent