SpringCloud微服务熔断器使用详解

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

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

@RestController
@RequestMapping("/hystrix")
public class HystrixController {
    @Autowired
    private RestTemplate restTemplate;
    /**
     * @param num 参数
     * @return 字符串
     */
    @HystrixCommand(
            commandProperties = {
                    @HystrixProperty(name = "circuitBreaker.enabled", value = "true"),
                    @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "5"),  // 默认20, 最小产生5次请求
                    @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "5000"), // 熔断时间, 该时间内快速失败
                    @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "50"), // 10s内失败率达到50%触发熔断
            }, // 10s 内最少 5 个请求, 如果失败率大于 50% 则触发熔断
            fallbackMethod = "fallback"
    )  // 服务调用失败时，触发熔断进行降级
    @GetMapping("/test")
    public String test(@RequestParam Integer num) {
        if (num % 2 == 0) {
            return "访问正常";
        }
        List<?> list = restTemplate.getForObject("http://localhost:7070/product/list", List.class);
        assert list != null;
        return list.toString();
    }
    /**
     * 熔断时触发降级
     *
     * @param num 参数
     * @return 字符串
     */
    private String fallback(Integer num) {
        // 降级操作
        return "系统繁忙";
    }
}

@RestController
@RequestMapping("/hystrix")
public class HystrixController {
    @Autowired
    private RestTemplate restTemplate;
    @HystrixCommand(
            commandProperties = {
                    @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "500")
            },
            fallbackMethod = "timeout"
    )
    @GetMapping("/timeout")
    public String timeoutTest(){
        return restTemplate.getForObject("http://localhost:7070/product/list", String.class);
    }
    /**
     * 超时时触发降级
     *
     * @return 字符串
     */
    private String timeout() {
        // 降级操作
        return "请求超时";
    }
}

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

@SpringBootApplication
@ComponentScan(basePackages = {  
        "com.study.provider.service",  // feign 包目录
        "com.study.hystrix"  // 当前模块启动目录
})
@EnableFeignClients(basePackages = "com.study.provider.service")  // feign 目录
public class HystrixApplication {
    public static void main(String[] args) {
        SpringApplication.run(HystrixApplication.class, args);
    }
}

@RestController
@RequestMapping("/hystrixFeign")
public class HystrixFeignController {
    @Qualifier("com.study.provider.service.ProductionService")
    @Autowired
    ProductionService productService;  // feign Client 
    @GetMapping("test")
    public String test(){
        return productService.getProduction(1).toString();   // 远程调用
    }
}

@FeignClient(value = "provider", fallback = ProductionFallback.class)   // fallback 用于熔断
public interface ProductionService {
    @RequestMapping("/product/getProduction")
    Object getProduction(@RequestParam Integer id);
}

@Component
public class ProductionFallback implements ProductionService {
    @Override
    public Object getProduction(Integer id) {
        return "请求失败";
    }
    @Override
    public Map createProduction(Object production) {
        return new HashMap<>();
    }
    @Override
    public Object selectByProduct(Object product) {
        return "请求失败";
    }
}