fallback method wasn't found: fallback([class java.lang.Boolean])

不念不忘少年蓝@ 2023-06-30 02:17 82阅读 0赞

1.  通过@HystrixCommand 来配置hystrix熔断的时候，超时时间设置的3秒，碰到了fallback method wasn’t found: fallback(\[class java.lang.Boolean\])，配置的接口方法有个Boolean类型的参数，而fallbackMethod对应的熔断方法是无参的，代码如下所示：

@GetMapping("/fallback")
    public Mono<String> fallback() { 
       return Mono.just("hystrix common, fallback");
    }
    
    
    @HystrixCommand(fallbackMethod = "fallback", commandProperties = { 
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "3000")
    })
    @GetMapping("/test/fallback")
    public String index(@RequestParam(value = "isSleep", defaultValue = "true") Boolean isSleep) throws InterruptedException { 
       log.info("是否睡眠：{}, 开始时间是：{}", isSleep, LocalDateTime.now());
       if (isSleep){ 
           TimeUnit.SECONDS.sleep(6);
       }
       log.info("结束时间是：{}", LocalDateTime.now());
       return "睡眠结束";
    }

如图所示，postman请求  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI_size_16_color_FFFFFF_t_70]  
2. 再熔断方法添加参数  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI_size_16_color_FFFFFF_t_70 1]  
接着测试，如图所示，会出现如下错误

{ 
        "timestamp": "2020-01-14T02:46:56.971+0000",
        "path": "/test/fallback",
        "status": 500,
        "error": "Internal Server Error",
        "message": "Incompatible return types. \nCommand method: public java.lang.String com.txzhang.springcloud.GatewayClientApplication.index(java.lang.Boolean) throws java.lang.InterruptedException;\nFallback method: public reactor.core.publisher.Mono com.txzhang.springcloud.GatewayClientApplication.fallback(java.lang.Boolean);\nHint: Fallback method 'public reactor.core.publisher.Mono com.txzhang.springcloud.GatewayClientApplication.fallback(java.lang.Boolean)' must return: class java.lang.String or its subclass"
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI_size_16_color_FFFFFF_t_70 2]

> 这是因为熔断方法的返回值和被熔断方法的返回值不一样

1.  修改熔断发方法的返回值为String

@GetMapping("/fallback")
    public String fallback(Boolean isSleep) { 
        log.debug("参数 isSleep : {}", isSleep);
        return "hystrix common, fallback";
    }

测试如图所示，正常熔断了  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI_size_16_color_FFFFFF_t_70 3]

**总结：熔断方法的返回值和参数列表需和原方法一致**

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200114094208297.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20200114104858684.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20200114104940626.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20200114113137669.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5ndHhzaXI=,size_16,color_FFFFFF,t_70