Spring Cloud OpenFeign：基于Ribbon和Hystrix的声明式服务调用

迈不过友情╰ 2024-04-22 19:04 66阅读 0赞

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## 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

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