SpringCloud集成Hystrix熔断过程分步分解

版本：

SpringBoot 2.6.1

SpringCloud 2021.0.0

依赖

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
	<version>2.1.6.RELEASE</version>
</dependency>

贴@EnableHystrix注解

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

在需要熔断的接口上贴@HystrixCommand注解

@RequestMapping("/consumerOne")
@RestController
public class ControllerOne {
    @Autowired
    private RestTemplate restTemplate;
    private String providerOneName = "provider-one";
    @HystrixCommand(fallbackMethod = "fallbackMethodOne")
    @RequestMapping("/serviceOne/{msg}")
    public String serviceOne(@PathVariable("msg") String msg) {
        return restTemplate.getForObject("http://" + providerOneName + "/providerOne/serviceOne/" + msg, String.class);
    }
	/** 熔断回调方法 */
    private String fallbackMethodOne(String msg) {
        return "熔断一默认返回:" + msg;
    }
}

异常熔断测试

其中一个服务方抛异常，另一服务方正常返回

@RequestMapping("/providerOne")
@RestController
public class ControllerOne {
    @RequestMapping("/serviceOne/{msg}")
    public String serviceOne(@PathVariable("msg") String msg) {
        throw new RuntimeException();
        // return "8702:" + msg;
    }
}

@RequestMapping("/providerOne")
@RestController
public class ControllerOne {
    @RequestMapping("/serviceOne/{msg}")
    public String serviceOne(@PathVariable("msg") String msg) {
        return "8701:" + msg;
    }
}

访问结果：

超时熔断测试

全局

先配置默认超时时间为3秒（default为全局）

hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 3000

在这里插入代码片

其中一个接口睡眠4秒

@RequestMapping("/providerOne")
@RestController
public class ControllerOne {
    @RequestMapping("/serviceOne/{msg}")
    public String serviceOne(@PathVariable("msg") String msg) {
        try {
            Thread.sleep(4 * 1000);
            return "8702:" + msg;
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "8702:" + msg;
    }
}

访问结果：

当服务方为延时返回的那个时，访问等待了3秒返回熔断默认对象

另一个正常

单个接口

除了全局外，另外给serviceTwo接口配置独立的超时时间，其余不变

hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 3000
    serviceTwo:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 5000

增加一个路径为serviceTwo的接口

@RequestMapping("/consumerOne")
@RestController
public class ControllerOne {
    @Autowired
    private RestTemplate restTemplate;
    private String providerOneName = "provider-one";
    @HystrixCommand(fallbackMethod = "fallbackMethodOne")
    @RequestMapping("/serviceOne/{msg}")
    public String serviceOne(@PathVariable("msg") String msg) {
        return restTemplate.getForObject("http://" + providerOneName + "/providerOne/serviceOne/" + msg, String.class);
    }
    @HystrixCommand(fallbackMethod = "fallbackMethodOne")
    @RequestMapping("/serviceTwo/{msg}")
    public String serviceTwo(@PathVariable("msg") String msg) {
        return restTemplate.getForObject("http://" + providerOneName + "/providerOne/serviceOne/" + msg, String.class);
    }
    private String fallbackMethodOne(String msg) {
        return "熔断一默认返回:" + msg;
    }
}

测试结果：

一个为等待5秒返回结果

一个正常返回