OpenFeign 简介
OpenFeign 是一个声明式的 HTTP 客户端，使得服务间的 HTTP 调用更加简单。只需要创建一个接口并添加注解，即可实现服务调用。特点
- 声明式调用，接口定义清晰
- 集成负载均衡
- 支持熔断降级
- 支持请求/响应压缩
- 支持日志记录
基本使用
添加依赖
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>
启用 Feign
@SpringBootApplication
@EnableFeignClients // 启用 Feign 客户端
public class OrderServiceApplication {
public static void main(String[] args) {
SpringApplication.run(OrderServiceApplication.class, args);
}
}
定义 Feign 客户端
@FeignClient(name = "user-service") // 服务名
public interface UserClient {
@GetMapping("/users/{id}")
User getUser(@PathVariable("id") Long id);
@GetMapping("/users")
List<User> listUsers();
@GetMapping("/users/search")
List<User> searchUsers(@RequestParam("name") String name,
@RequestParam("age") Integer age);
@PostMapping("/users")
User createUser(@RequestBody User user);
@PutMapping("/users/{id}")
User updateUser(@PathVariable("id") Long id, @RequestBody User user);
@DeleteMapping("/users/{id}")
void deleteUser(@PathVariable("id") Long id);
}
使用 Feign 客户端
@Service
public class OrderService {
@Autowired
private UserClient userClient;
public Order getOrder(Long orderId) {
Order order = orderMapper.selectById(orderId);
// 调用用户服务
User user = userClient.getUser(order.getUserId());
order.setUser(user);
return order;
}
}
配置
日志配置
@Configuration
public class FeignConfig {
@Bean
public Logger.Level feignLoggerLevel() {
return Logger.Level.FULL;
}
}
| 日志级别 | 说明 |
|---|---|
| NONE | 不记录日志（默认） |
| BASIC | 仅记录请求方法、URL、响应状态码和执行时间 |
| HEADERS | BASIC + 请求和响应头 |
| FULL | 记录完整的请求和响应 |
logging:
level:
com.example.client: debug # Feign 客户端所在包
超时配置
spring:
cloud:
openfeign:
client:
config:
default: # 全局配置
connect-timeout: 5000
read-timeout: 5000
user-service: # 指定服务配置
connect-timeout: 3000
read-timeout: 3000
请求压缩
spring:
cloud:
openfeign:
compression:
request:
enabled: true
mime-types: text/xml,application/xml,application/json
min-request-size: 2048
response:
enabled: true
熔断降级
整合 Sentinel
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>
feign:
sentinel:
enabled: true
定义降级类
@FeignClient(name = "user-service", fallback = UserClientFallback.class)
public interface UserClient {
@GetMapping("/users/{id}")
User getUser(@PathVariable("id") Long id);
}
@Component
public class UserClientFallback implements UserClient {
@Override
public User getUser(Long id) {
// 降级逻辑
User user = new User();
user.setId(id);
user.setName("默认用户");
return user;
}
}
获取异常信息
@FeignClient(name = "user-service", fallbackFactory = UserClientFallbackFactory.class)
public interface UserClient {
@GetMapping("/users/{id}")
User getUser(@PathVariable("id") Long id);
}
@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
log.error("调用用户服务失败: {}", cause.getMessage());
User user = new User();
user.setId(id);
user.setName("降级用户");
return user;
}
};
}
}
拦截器
自定义请求拦截器
@Component
public class FeignRequestInterceptor implements RequestInterceptor {
@Override
public void apply(RequestTemplate template) {
// 获取当前请求
ServletRequestAttributes attributes = (ServletRequestAttributes)
RequestContextHolder.getRequestAttributes();
if (attributes != null) {
HttpServletRequest request = attributes.getRequest();
// 传递请求头
String token = request.getHeader("Authorization");
if (token != null) {
template.header("Authorization", token);
}
// 传递用户信息
String userId = request.getHeader("X-User-Id");
if (userId != null) {
template.header("X-User-Id", userId);
}
}
// 添加自定义请求头
template.header("X-Request-Id", UUID.randomUUID().toString());
}
}
最佳实践
抽取 Feign 接口到公共模块
project
├── user-api/ # 用户服务 API 模块
│ ├── src/
│ │ └── main/java
│ │ └── com.example.user.api
│ │ ├── client/
│ │ │ └── UserClient.java
│ │ ├── dto/
│ │ │ └── UserDTO.java
│ │ └── fallback/
│ │ └── UserClientFallback.java
│ └── pom.xml
│
├── user-service/ # 用户服务实现
│ └── ...
│
└── order-service/ # 订单服务（调用 user-api）
└── pom.xml
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
</dependencies>
<dependencies>
<dependency>
<groupId>com.example</groupId>
<artifactId>user-api</artifactId>
<version>1.0.0</version>
</dependency>
</dependencies>
@SpringBootApplication
@EnableFeignClients(basePackages = "com.example.user.api.client")
public class OrderServiceApplication {
public static void main(String[] args) {
SpringApplication.run(OrderServiceApplication.class, args);
}
}
继承方式定义接口
// 公共接口定义
public interface UserApi {
@GetMapping("/users/{id}")
User getUser(@PathVariable("id") Long id);
@PostMapping("/users")
User createUser(@RequestBody User user);
}
// Feign 客户端继承
@FeignClient(name = "user-service")
public interface UserClient extends UserApi {
}
// Controller 实现
@RestController
public class UserController implements UserApi {
@Autowired
private UserService userService;
@Override
public User getUser(Long id) {
return userService.findById(id);
}
@Override
public User createUser(User user) {
return userService.save(user);
}
}
性能优化
连接池配置
默认 Feign 使用 URLConnection，可以替换为 OkHttp 或 Apache HttpClient。<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-okhttp</artifactId>
</dependency>
spring:
cloud:
openfeign:
okhttp:
enabled: true
@Configuration
public class FeignOkHttpConfig {
@Bean
public OkHttpClient okHttpClient() {
return new OkHttpClient.Builder()
.connectTimeout(10, TimeUnit.SECONDS)
.readTimeout(30, TimeUnit.SECONDS)
.writeTimeout(30, TimeUnit.SECONDS)
.connectionPool(new ConnectionPool(100, 5, TimeUnit.MINUTES))
.build();
}
}