SpringCloud(Hoxton)--Hystrix服务降级（注解）

- 日理万妓 2021-08-27 17:03 463阅读 0赞

#### cloud-provider-hystrix-payment8001模拟支付模块 ####

依赖：

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <parent>
            <artifactId>cloud2020</artifactId>
            <groupId>pers.zhang.springcloud</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>cloud-provider-hystrix-payment8001</artifactId>
    
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            <dependency>
                <groupId>pers.zhang.springcloud</groupId>
                <artifactId>cloud-api-commons</artifactId>
                <version>${project.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <scope>runtime</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
    </project>

配置：application.yml

server:
      port: 8001
    
    spring:
      application:
        name: cloud-provider-hystrix-payment
    
    eureka:
      client:
        register-with-eureka: true
        fetch-registry: true
        service-url:
          defaultZone: http://eureka7001.com:7001/eureka
          #defaultZone: http://eureka7001.com:7001/eureka,http://wureka7002.com:7002/eureka

Service：

@Service
    public class PaymentService { 
    
        /** * 正常访问，肯定OK * @param id * @return */
        public String paymentInfo_OK(Integer id) { 
            return "线程池：" + Thread.currentThread().getName() + " paymentInfo_OK, id:" + id;
        }
    
    
        /** * 超时错误 * @param id * @return */
        @HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler", commandProperties = { 
                @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "2000")
        })//指定超时回调,时间为2秒
        public String paymentInfo_TimeOut(Integer id) { 
            //int a = 10 / 0;
            try { //睡3秒，模拟超时
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) { 
                e.printStackTrace();
            }
            return "线程池：" + Thread.currentThread().getName() + " paymentInfo_TimeOut, id:" + id;
        }
    
    
        public String paymentInfo_TimeOutHandler(Integer id) { 
            return "线程池：" + Thread.currentThread().getName() + " 系统繁忙，请稍后再试, id:" + id + "超时回调";
        }
    }

Controller:

@RestController
    @Slf4j
    public class PaymentController { 
    
        @Resource
        PaymentService paymentService;
    
        @Value("${server.port}")
        String serverPort;
    
        @GetMapping("/payment/hystrix/ok/{id}")
        public String paymentInfo_OK(@PathVariable("id") Integer id) { 
            String result = paymentService.paymentInfo_OK(id);
            log.info("*****result:" + result);
            return result;
        }
    
        @GetMapping("/payment/hystrix/timeout/{id}")
        public String paymentInfo_TimeOut(@PathVariable("id") Integer id) { 
            String result = paymentService.paymentInfo_TimeOut(id);
            log.info("*****result:" + result);
            return result;
        }
    }

启动类：

@SpringBootApplication
    @EnableEurekaClient
    @EnableCircuitBreaker//开启
    public class PaymentHystrixMain8001 { 
        public static void main(String[] args) { 
            SpringApplication.run(PaymentHystrixMain8001.class, args);
        }
    }

#### cloud-consumer-feign-hystrix-order80模拟订单模块 ####

依赖：

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <parent>
            <artifactId>cloud2020</artifactId>
            <groupId>pers.zhang.springcloud</groupId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>cloud-consumer-feign-hystrix-order80</artifactId>
    
        <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>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            
            <dependency>
                <groupId>pers.zhang.springcloud</groupId>
                <artifactId>cloud-api-commons</artifactId>
                <version>${project.version}</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <scope>runtime</scope>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
    </project>

配置：application.yml

server:
      port: 80
    
    eureka:
      client:
        register-with-eureka: false
        service-url:
          defaultZone: http://eureka7001.com:7001/eureka/
    feign:
      hystrix:
        enabled: true #开启hystrix

Service:

@Component
    @FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT")//指定调用的服务名
    public interface PaymentHystrixService { 
    
        @GetMapping("/payment/hystrix/ok/{id}")
        public String paymentInfo_OK(@PathVariable("id") Integer id);
    
        @GetMapping("/payment/hystrix/timeout/{id}")
        public String paymentInfo_TimeOut(@PathVariable("id") Integer id);
    
    }

Controller:

@RestController
    @Slf4j
    public class OrderHystrixController { 
    
        @Resource
        PaymentHystrixService paymentHystrixService;
    
        @GetMapping("/consumer/payment/hystrix/ok/{id}")
        public String paymentInfo_OK(@PathVariable("id") Integer id) { 
            String result = paymentHystrixService.paymentInfo_OK(id);
            return result;
        }
    
        @GetMapping("/consumer/payment/hystrix/timeout/{id}")
        @HystrixCommand(fallbackMethod = "paymentTimeOutFallbackMethod", commandProperties = { 
                @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1500")//超时1.5秒
        })
        public String paymentInfo_TimeOut(@PathVariable("id") Integer id) { 
            String result = paymentHystrixService.paymentInfo_TimeOut(id);
            return result;
        }
    
        public String paymentTimeOutFallbackMethod(@PathVariable("id") Integer id) { 
            return "我是消费者80，对方支付系统繁忙，请10秒后再试或者自己运行出错请检查自己。";
        }
    }

启动类：

@SpringBootApplication
    @EnableFeignClients
    @EnableHystrix//开启Hystrix
    public class OrderHystrixMain80 { 
        public static void main(String[] args) { 
            SpringApplication.run(OrderHystrixMain80.class, args);
        }
    }

#### 测试 ####

我们在服务的提供方和消费方都使用了Hystrix，但是多数情况下只在消费方配置Hystrix。

启动Eureka，在启动支付和订单微服务。

**先在8001端口进行本地测试：**

访问：`localhost:8001/payment/hystrix/ok/35`，成功  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70]

访问：`localhost:8001/payment/hystrix/timeout/33`,失败，程序中睡眠3秒，触发Hystrix设置的2秒时限，服务降级，调用fallback方法：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 1]

**通过80端口使用Feign调用8001：**

访问：`localhost/consumer/payment/hystrix/ok/22`：成功：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 2]  
访问：`localhost/consumer/payment/hystrix/timeout/11`：失败，订单模块作为消费方做出的超时限制为1.5秒，等待1.5秒无返回立即触发服务降级，调用fallback方法。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 3]

#### @DefaultProperties ####

每个方法都有一个fallback方法，为了避免代码膨胀，应该有一个同一的方法和自定义的fallback方法分开。

可以在类上加@Defaultproperties注解指定一个通用的fallback方法，凡是标注了@HystrixCommand但没有指定@HystrixProperty的方法，均使用@DefaultProperties指定的fallback方法。

修改80端口的Controller：

@RestController
    @Slf4j
    @DefaultProperties(defaultFallback = "payment_Global_FallbackMethod")
    public class OrderHystrixController { 
    
        @Resource
        PaymentHystrixService paymentHystrixService;
    
        @GetMapping("/consumer/payment/hystrix/ok/{id}")
        public String paymentInfo_OK(@PathVariable("id") Integer id) { 
            String result = paymentHystrixService.paymentInfo_OK(id);
            return result;
        }
    
        @GetMapping("/consumer/payment/hystrix/timeout/{id}")
        //未指定fallback，使用@DefaultProperties指定的payment_Global_FallbackMethod
        @HystrixCommand
        // @HystrixCommand(fallbackMethod = "paymentTimeOutFallbackMethod", commandProperties = { 
        // @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1500")//超时1.5秒
        // })
        public String paymentInfo_TimeOut(@PathVariable("id") Integer id) { 
            int a = 10 / 0;
            String result = paymentHystrixService.paymentInfo_TimeOut(id);
            return result;
        }
    
        public String paymentTimeOutFallbackMethod(@PathVariable("id") Integer id) { 
            return "我是消费者80，对方支付系统繁忙，请10秒后再试或者自己运行出错请检查自己。";
        }
        
        //默认fallback
        public String payment_Global_FallbackMethod() { 
            return "Global异常处理信息，请稍后再试...";
        }
    }

重启，访问：`localhost/consumer/payment/hystrix/timeout/33`，失败，跳转到全局fallback：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 4]

#### fallback解耦 ####

目前业务逻辑和fallback都混在一起，应该将两者分开。

只需要为Feign客户端定义的接口添加一个服务降级处理的实现 类即可实现解耦。

新建类PaymentFallbackService，实现PaymentHystrixService接口：

@Component
    public class PaymentFallbackService implements PaymentHystrixService { 
        @Override
        public String paymentInfo_OK(Integer id) { 
            return "-------PaymentFallbackService paymentInfo_OK fall back--------";
        }
    
        @Override
        public String paymentInfo_TimeOut(Integer id) { 
            return "-------PaymentFallbackService paymentInfo_TimeOut fall back--------";
        }
    }

在@FeignClient中指明fallback处理类：  
![在这里插入图片描述][20200317225640961.png]

重启服务，访问：`localhost/consumer/payment/hystrix/ok/55`，成功：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 5]

关闭8001服务，模拟宕机，再次访问：`localhost/consumer/payment/hystrix/ok/55`：失败，执行PaymentFallbackService中对应的fallback方法  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NvbGRfX19wbGF5_size_16_color_FFFFFF_t_70 6]

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[20200317225640961.png]: /images/20210813/3cb0c871f10f4bfbb06f35c26f0131a9.png
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