spring-cloud之hystrix学习笔记

入门示例

1. 添加依赖

   <dependency>
       <groupId>org.springframework.cloud</groupId>
       <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
   </dependency>
   

2. 添加注解@EnableHystrix

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

3. 编写业务并使用@HystrixCommand配置方法的降级处理

   @Service
   public class UserServiceImpl implements UserService {
         
         
       @Override
       @HystrixCommand(fallbackMethod = "defaultUser")
       public String getUser(String username){
         
         
           if (username.equalsIgnoreCase("spring")){
         
         
               return "this is real user" ;
           }else {
         
         
               throw new RuntimeException() ;
           }
       }
       // 出错调用该方法返回预设友好错误
       public String defaultUser(String username){
         
         
           return "The user does not exist in this system" ;
       }
   }
   

4. 编写controller测试service代码

   @RestController
   public class UserController {
         
         
       @Autowired
       private UserService userService ;
       @GetMapping("/getUser")
       public String getUser(String username){
         
         
           return userService.getUser(username) ;
       }
   }
   

feign中使用断路器

1. 添加依赖

   <dependencies>
       <dependency>
           <groupId>org.springframework.cloud</groupId>
           <artifactId>spring-cloud-starter-openfeign</artifactId>
       </dependency>
       <dependency>
           <groupId>org.springframework.cloud</groupId>
           <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
       </dependency>
   </dependencies>
   

2. 添加@EnableFeignClients,@EnableDiscoveryClient注解

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

3. 打开feign断路配置

   # feign中hystrix 默认关闭
   feign.hystrix.enabled=true
   

4. 编写feign接口类

   @Primary
   @FeignClient(name = "client-a", fallback = UserFeignServiceFallback.class)
   public interface UserFeignService {
         
         
       @RequestMapping(value = "/getUser", method = RequestMethod.GET)
       String getUser(@RequestParam("username") String username) ;
   }
   

5. 编写feign接口降级类

   @Component
   public class UserFeignServiceFallback implements UserFeignService {
         
         
       @Override
       public String getUser(String username) {
         
         
           return "The user does not exist in this system, please confirm username";
       }
   }
   

6. 编写业务方法调用feign接口

   @RestController
   public class UserFeignController {
         
         
       @Autowired
       private UserFeignService userFeignService ;
       @GetMapping("/getFeignUser")
       public String getUser(String username){
         
         
           return userFeignService.getUser(username) ;
       }
   }