Spring Cloud OpenFeign：基于Ribbon和Hystrix的声明式服务调用
Spring Cloud OpenFeign是一个声明式的服务调用框架，基于Feign并整合了Ribbon和Hystrix；目标是简化分布式系统中编写服务间调用的代码，并提供一种更加优雅和便捷的方式来进行服务之间的通信
创建feign-service模块
- 依赖导入
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix -eureka-client</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency>
- application.yml配置
server: port: 8701 spring: application: name: feign-service eureka: client: register-with-eureka: true fetch-registry: true service-url: defaultZone: http://localhost:8001/eureka/
- 启动类上添加@EnableFeignClients注解来启用Feign的客户端功能
@EnableFeignClients @EnableDiscoveryClient @SpringBootApplication public class FeignServiceApplication { public static void main(String[] args) { SpringApplication.run(FeignServiceApplication.class, args); } }
- 添加UserService接口完成对user-service服务的接口绑定
@FeignClient(value = "user-service") public interface UserService { @PostMapping("/user/create") CommonResult create(@RequestBody User user); @GetMapping("/user/{id}") CommonResult<User> getUser(@PathVariable Long id); }
- 添加UserFeignController调用UserService实现服务调用
@RestController @RequestMapping("/user") public class UserFeignController { @Autowired private UserService userService; @PostMapping("/create") public CommonResult create(@RequestBody User user) { return userService.create(user); } @GetMapping("/{id}") public CommonResult getUser(@PathVariable Long id) { return userService.getUser(id); } }
Feign中的服务降级
微服务架构中，服务降级是一种应对高并发或系统故障的策略，用于保证系统的可用性和稳定性；Feign是一个声明式的Web服务客户端，可以与Spring Cloud等微服务框架集成，简化服务之间的调用
- 添加服务降级实现类UserFallbackService
@Component public class UserFallbackService implements UserService { @Override public CommonResult create(User user) { User defaultUser = new User(-1L, "defaultUser", "123456"); return new CommonResult<>(defaultUser); } @Override public CommonResult<User> getUser(Long id) { User defaultUser = new User(-1L, "defaultUser", "123456"); return new CommonResult<>(defaultUser); } @Override public CommonResult<User> getByUsername(String username) { User defaultUser = new User(-1L, "defaultUser", "123456"); return new CommonResult<>(defaultUser); } @Override public CommonResult update(User user) { return new CommonResult("调用失败，服务被降级",500); } @Override public CommonResult delete(Long id) { return new CommonResult("调用失败，服务被降级",500); } }
- 修改UserService接口，设置服务降级处理类为UserFallbackService
@FeignClient(value = "user-service",fallback = UserFallbackService.class) public interface UserService { }
- 修改application.yml，开启Hystrix功能
feign: hystrix: enabled: true #在Feign中开启Hystrix
日志打印功能
Feign提供了日志打印功能，我们可以通过配置来调整日志级别，从而了解Feign中Http请求的细节
日志级别
- NONE：默认的，不显示任何日志
- BASIC：仅记录请求方法、URL、响应状态码及执行时间
- HEADERS：除了BASIC中定义的信息之外，还有请求和响应的头信息
- FULL：除了HEADERS中定义的信息之外，还有请求和响应的正文及元数据
通过配置开启更为详细的日志
- 通过java配置来使Feign打印最详细的Http请求日志信息
@Configuration public class FeignConfig { @Bean Logger.Level feignLoggerLevel() { return Logger.Level.FULL; } }
- application.yml中配置需要开启日志的Feign客户端；配置UserService的日志级别为debug
logging: level: com.macro.cloud.service.UserService: debug
Feign的常用配置
feign: hystrix: enabled: true #在Feign中开启Hystrix compression: request: enabled: false #是否对请求进行GZIP压缩 mime-types: text/xml,application/xml,application/json #指定压缩的请求数据类型 min-request-size: 2048 #超过该大小的请求会被压缩 response: enabled: false #是否对响应进行GZIP压缩 logging: level: #修改日志级别 com.macro.cloud.service.UserService: debug
🌼 结语：创作不易，如果觉得博主的文章赏心悦目，还请——
点赞👍收藏⭐️评论📝
