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Eureka与Feign集成

Salmon2026/1/15大约 3 分钟EurekaFeignOpenFeign

Eureka 与 Feign 集成

一、Feign 简介

Feign 是一个声明式的 HTTP 客户端，使用注解方式定义接口，自动实现服务调用。

1.1 RestTemplate vs Feign

// RestTemplate 方式
String url = "http://user-service/user/" + id;
User user = restTemplate.getForObject(url, User.class);

// Feign 方式
User user = userClient.getUser(id);

1.2 Feign 特点

  • 声明式接口定义
  • 自动集成 Ribbon 负载均衡
  • 支持 Hystrix 熔断
  • 支持请求压缩
  • 支持日志输出

二、快速开始

2.1 添加依赖

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

2.2 启用 Feign

@SpringBootApplication
@EnableFeignClients  // 启用 Feign
public class OrderServiceApplication {
    public static void main(String[] args) {
        SpringApplication.run(OrderServiceApplication.class, args);
    }
}

2.3 定义 Feign 接口

@FeignClient(name = "user-service")  // 指定服务名
public interface UserClient {
    
    @GetMapping("/user/{id}")
    User getUser(@PathVariable("id") Long id);
    
    @GetMapping("/user/list")
    List<User> listUsers();
    
    @PostMapping("/user")
    User createUser(@RequestBody User user);
    
    @PutMapping("/user/{id}")
    User updateUser(@PathVariable("id") Long id, @RequestBody User user);
    
    @DeleteMapping("/user/{id}")
    void deleteUser(@PathVariable("id") Long id);
}

2.4 使用 Feign 客户端

@RestController
@RequestMapping("/order")
public class OrderController {
    
    @Autowired
    private UserClient userClient;
    
    @GetMapping("/{id}")
    public Order getOrder(@PathVariable Long id) {
        // 直接调用 Feign 接口
        User user = userClient.getUser(id);
        
        Order order = new Order();
        order.setId(id);
        order.setUser(user);
        return order;
    }
}

三、Feign 配置

3.1 超时配置

feign:
  client:
    config:
      default:  # 全局配置
        connectTimeout: 5000
        readTimeout: 10000
      user-service:  # 针对特定服务
        connectTimeout: 3000
        readTimeout: 5000

3.2 日志配置

feign:
  client:
    config:
      default:
        loggerLevel: FULL  # NONE, BASIC, HEADERS, FULL

logging:
  level:
    com.example.client: DEBUG

日志级别说明：

级别说明
NONE不记录日志
BASIC记录请求方法、URL、响应状态码、执行时间
HEADERS记录 BASIC + 请求/响应头
FULL记录 HEADERS + 请求/响应体

3.3 配置类方式

@Configuration
public class FeignConfig {
    
    @Bean
    public Logger.Level feignLoggerLevel() {
        return Logger.Level.FULL;
    }
    
    @Bean
    public Request.Options options() {
        return new Request.Options(5000, 10000);
    }
}

四、请求拦截器

4.1 添加请求头

@Component
public class FeignRequestInterceptor implements RequestInterceptor {
    
    @Override
    public void apply(RequestTemplate template) {
        // 添加认证头
        template.header("Authorization", "Bearer " + getToken());
        
        // 添加追踪ID
        template.header("X-Trace-Id", UUID.randomUUID().toString());
    }
    
    private String getToken() {
        // 从上下文获取 token
        return "your-token";
    }
}

4.2 传递请求头

@Component
public class FeignHeaderInterceptor implements RequestInterceptor {
    
    @Override
    public void apply(RequestTemplate template) {
        ServletRequestAttributes attributes = (ServletRequestAttributes) 
                RequestContextHolder.getRequestAttributes();
        
        if (attributes != null) {
            HttpServletRequest request = attributes.getRequest();
            // 传递原始请求的 Authorization 头
            String auth = request.getHeader("Authorization");
            if (auth != null) {
                template.header("Authorization", auth);
            }
        }
    }
}

五、Feign 与 Hystrix 集成

5.1 启用 Hystrix

feign:
  hystrix:
    enabled: true

5.2 定义降级类

@Component
public class UserClientFallback implements UserClient {
    
    @Override
    public User getUser(Long id) {
        User user = new User();
        user.setId(id);
        user.setName("默认用户");
        return user;
    }
    
    @Override
    public List<User> listUsers() {
        return Collections.emptyList();
    }
    
    @Override
    public User createUser(User user) {
        return null;
    }
    
    @Override
    public User updateUser(Long id, User user) {
        return null;
    }
    
    @Override
    public void deleteUser(Long id) {
        // 降级处理
    }
}

5.3 配置降级

@FeignClient(name = "user-service", fallback = UserClientFallback.class)
public interface UserClient {
    // ...
}

5.4 获取异常信息

@Component
public class UserClientFallbackFactory implements FallbackFactory<UserClient> {
    
    @Override
    public UserClient create(Throwable cause) {
        return new UserClient() {
            @Override
            public User getUser(Long id) {
                // 可以记录异常信息
                log.error("调用 user-service 失败: {}", cause.getMessage());
                return new User();
            }
            // ...
        };
    }
}

@FeignClient(name = "user-service", fallbackFactory = UserClientFallbackFactory.class)
public interface UserClient {
    // ...
}

六、请求压缩

6.1 配置压缩

feign:
  compression:
    request:
      enabled: true
      mime-types: text/xml,application/xml,application/json
      min-request-size: 2048
    response:
      enabled: true

七、继承特性

7.1 定义公共接口

// 公共模块
public interface UserApi {
    
    @GetMapping("/user/{id}")
    User getUser(@PathVariable("id") Long id);
    
    @PostMapping("/user")
    User createUser(@RequestBody User user);
}

7.2 服务提供者实现

@RestController
public class UserController implements UserApi {
    
    @Override
    public User getUser(Long id) {
        // 实现逻辑
    }
    
    @Override
    public User createUser(User user) {
        // 实现逻辑
    }
}

7.3 Feign 客户端继承

@FeignClient(name = "user-service")
public interface UserClient extends UserApi {
    // 自动继承父接口的方法定义
}

八、多参数请求

8.1 GET 请求多参数

@FeignClient(name = "user-service")
public interface UserClient {
    
    // 方式1：@RequestParam
    @GetMapping("/user/search")
    List<User> search(@RequestParam("name") String name, 
                      @RequestParam("age") Integer age);
    
    // 方式2：@SpringQueryMap
    @GetMapping("/user/search")
    List<User> search(@SpringQueryMap UserQuery query);
}

8.2 POST 请求

@FeignClient(name = "user-service")
public interface UserClient {
    
    // JSON 请求体
    @PostMapping("/user")
    User createUser(@RequestBody User user);
    
    // 表单请求
    @PostMapping(value = "/user/form", consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE)
    User createUserByForm(@RequestParam("name") String name, 
                          @RequestParam("age") Integer age);
}

九、总结

核心要点：

  1. 声明式调用：使用注解定义接口
  2. 自动负载均衡：集成 Ribbon
  3. 熔断降级：集成 Hystrix
  4. 灵活配置：超时、日志、压缩等
最近更新:
贡献者: Salmon