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OpenFeign使用

news 2025/10/11 9:10:34

OpenFeign使用

OpenFeign是一个声明式的HTTP客户端，它使得编写Web服务客户端更加简单。通过注解的方式，可以轻松定义和调用HTTP API。

1. OpenFeign 的作用

主要特性：

声明式客户端：通过接口和注解定义HTTP API
集成Ribbon：内置客户端负载均衡
集成Hystrix：支持服务降级和熔断（早期版本）
与Spring Cloud集成：无缝集成Spring Cloud生态系统
简化HTTP调用：自动处理HTTP请求/响应序列化

2. 基本用法

添加依赖

<!-- Spring Cloud OpenFeign -->
<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

启用OpenFeign

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

定义Feign客户端接口

@FeignClient(name = "user-service", url = "http://localhost:8080")
public interface UserServiceClient {@GetMapping("/users/{id}")User getUserById(@PathVariable("id") Long id);@PostMapping("/users")User createUser(@RequestBody User user);@GetMapping("/users")List<User> getUsers(@RequestParam("page") int page, @RequestParam("size") int size);
}

使用Feign客户端

@RestController
@RequestMapping("/api")
public class UserController {@Autowiredprivate UserServiceClient userServiceClient;@GetMapping("/users/{id}")public ResponseEntity<User> getUser(@PathVariable Long id) {User user = userServiceClient.getUserById(id);return ResponseEntity.ok(user);}
}

3. 详细配置

自定义配置类

@Configuration
public class FeignConfig {@Beanpublic Logger.Level feignLoggerLevel() {return Logger.Level.FULL;  // 设置日志级别}@Beanpublic RequestInterceptor requestInterceptor() {return requestTemplate -> {// 添加请求头requestTemplate.header("X-Request-Source", "feign-client");};}@Beanpublic Retryer feignRetryer() {return new Retryer.Default(1000, 8000, 3);  // 重试配置}
}

在Feign客户端使用配置

@FeignClient(name = "user-service", configuration = FeignConfig.class)
public interface UserServiceClient {// ...
}

4. 服务发现集成

与Eureka集成

@FeignClient(name = "user-service")  // 使用服务名，不需要url
public interface UserServiceClient {@GetMapping("/users/{id}")User getUserById(@PathVariable("id") Long id);
}

负载均衡示例

@Service
public class UserService {@Autowiredprivate UserServiceClient userServiceClient;public User getUserWithFallback(Long id) {try {return userServiceClient.getUserById(id);} catch (Exception e) {// 多个user-service实例会自动负载均衡return userServiceClient.getUserById(id); // 会重试其他实例}}
}

5. 性能优化配置

连接池配置

feign:httpclient:enabled: true  # 启用HTTP客户端连接池max-connections: 200  # 最大连接数max-connections-per-route: 50  # 每个路由最大连接数okhttp:enabled: false  # 禁用OKHttp（根据需求选择）client:config:default:  # 全局默认配置connectTimeout: 5000  # 连接超时时间readTimeout: 10000    # 读取超时时间loggerLevel: basic    # 日志级别user-service:  # 特定服务配置connectTimeout: 3000readTimeout: 5000

压缩配置

feign:compression:request:enabled: true  # 启用请求压缩mime-types: text/xml,application/xml,application/jsonmin-request-size: 2048  # 最小压缩大小response:enabled: true  # 启用响应压缩

6. 实际应用示例

完整的服务间调用

// 用户服务Feign客户端
@FeignClient(name = "user-service", path = "/api/v1/users")
public interface UserServiceClient {@GetMapping("/{userId}")ResponseEntity<UserDTO> getUser(@PathVariable Long userId);@GetMapping("/search")ResponseEntity<List<UserDTO>> searchUsers(@RequestParam String keyword,@RequestParam(defaultValue = "0") int page,@RequestParam(defaultValue = "10") int size);
}// 订单服务Feign客户端  
@FeignClient(name = "order-service",path = "/api/v1/orders")
public interface OrderServiceClient {@GetMapping("/user/{userId}")ResponseEntity<List<OrderDTO>> getUserOrders(@PathVariable Long userId);
}// 业务服务中使用
@Service
@Transactional
public class BusinessService {@Autowiredprivate UserServiceClient userServiceClient;@Autowiredprivate OrderServiceClient orderServiceClient;public UserWithOrdersDTO getUserWithOrders(Long userId) {// 调用用户服务ResponseEntity<UserDTO> userResponse = userServiceClient.getUser(userId);UserDTO user = userResponse.getBody();// 调用订单服务ResponseEntity<List<OrderDTO>> ordersResponse = orderServiceClient.getUserOrders(userId);List<OrderDTO> orders = ordersResponse.getBody();return UserWithOrdersDTO.builder().user(user).orders(orders).build();}
}