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

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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:8701spring:application:name: feign-service
eureka:client:register-with-eureka:truefetch-registry:trueservice-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@SpringBootApplicationpublicclassFeignServiceApplication{publicstaticvoidmain(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")publicinterfaceUserService{@PostMapping("/user/create")CommonResultcreate(@RequestBodyUser user);@GetMapping("/user/{id}")CommonResult<User>getUser(@PathVariableLong id);}

• 添加UserFeignController调用UserService实现服务调用

@RestController@RequestMapping("/user")publicclassUserFeignController{@AutowiredprivateUserService userService;@PostMapping("/create")publicCommonResultcreate(@RequestBodyUser user){return userService.create(user);}@GetMapping("/{id}")publicCommonResultgetUser(@PathVariableLong 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

@ComponentpublicclassUserFallbackServiceimplementsUserService{@OverridepublicCommonResultcreate(User user){User defaultUser =newUser(-1L,"defaultUser","123456");returnnewCommonResult<>(defaultUser);}@OverridepublicCommonResult<User>getUser(Long id){User defaultUser =newUser(-1L,"defaultUser","123456");returnnewCommonResult<>(defaultUser);}@OverridepublicCommonResult<User>getByUsername(String username){User defaultUser =newUser(-1L,"defaultUser","123456");returnnewCommonResult<>(defaultUser);}@OverridepublicCommonResultupdate(User user){returnnewCommonResult("调用失败，服务被降级",500);}@OverridepublicCommonResultdelete(Long id){returnnewCommonResult("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)publicinterfaceUserService{}

• 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

@ConfigurationpublicclassFeignConfig{@BeanLogger.LevelfeignLoggerLevel(){returnLogger.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——

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