SpringCloud学习-part62 sentinel服务熔断与OpenFeign

目标

使用OpenFeign结合与精简restTemplate与负载均衡步骤，降低代码的耦合度。

文件结构

pom

注意引入openfeign的启动依赖

        
            org.springframework.cloud
            spring-cloud-starter-openfeign
        

完整pom

    
        cloud2020
        com.ezerbel.cloud
        1.0-SNAPSHOT
    
    4.0.0

    cloudalibaba-consumer-nacos-order84

    
        
            com.alibaba.cloud
            spring-cloud-starter-alibaba-nacos-discovery
        

        
            com.ezerbel.cloud
            cloud-api-commons
            ${project.version}
        

        
            org.springframework.boot
            spring-boot-starter-web
        
        
        
            org.springframework.boot
            spring-boot-starter-actuator
        

        
        
            org.springframework.boot
            spring-boot-devtools
            runtime
            true
        
        
            org.projectlombok
            lombok
            true
        
        
            org.springframework.cloud
            spring-cloud-starter-openfeign
        
        
            com.alibaba.cloud
            spring-cloud-starter-alibaba-sentinel
        
        
            com.alibaba.csp
            sentinel-core
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
    

yml

开启OpenFeign对sentinel的支持

feign:
  sentinel:
    enabled: true

完整yml

server:
  port: 84

spring:
  application:
    name: nacos-order-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
    sentinel:
      transport:
        #配置Sentinel dashboard地址
        dashboard: localhost:8080
        #默认8719端口，假如被占用会自动从8719开始依次+1扫描,直至找到未被占用的端口
        port: 8719
      filter:
        enabled: false
#消费者将要去访问的微服务名称（成功注册入nacos的微服务提供者）,用于resttemplate调用前的属性注入
service-url:
  nacos-user-service: http://nacos-payment-provider
management:
  endpoints:
    web:
      exposure:
        include: '*'
# 激活Sentinel对Feign的支持
feign:
  sentinel:
    enabled: true

PaymentService接口

使用服务注册中心中的nacos-payment-provider服务，并能够调用其paymentSQL方法。

@FeignClient(value = "nacos-payment-provider",fallback = PaymentFallbackService.class)
public interface PaymentService
{
    @GetMapping(value = "/paymentSQL/{id}")
    public CommonResult paymentSQL(@PathVariable("id") Long id);
}

PaymentService

@FeignClient(value = "nacos-payment-provider",fallback = PaymentFallbackService.class)
public interface PaymentService
{
    @GetMapping(value = "/paymentSQL/{id}")
    public CommonResult paymentSQL(@PathVariable("id") Long id);
}

限流异常处理方法

public class BlockHandlers {

    public static CommonResult paymentSQLBlockHandler(@PathVariable Long id, BlockException exception){
        Payment payment = new Payment(id,null);
        String msg = exception.getClass().getCanonicalName() + " ，请求被block，服务暂时不可用！ request id = " + id;
        return  new CommonResult<>(432,msg,payment) ;
    }
}

内部运行时异常处理

public class FallBacks {
    public static CommonResult paymentSQLFallBack(@PathVariable Long id,Throwable e){
        Payment payment = new Payment(id,null);
        String msg = e.getClass().getCanonicalName() + " ，请求出现异常，现在回滚！ request id = " + id;
        return  new CommonResult<>(434,msg,payment) ;
    }
}

熔断处理方法

当目标服务不可用或出现异常时，调用此类中的同名方法

@Component
public class PaymentFallbackService implements PaymentService
{
    @Override
    public CommonResult paymentSQL(Long id)
    {
        return new CommonResult<>(44444,"服务降级返回,---PaymentFallbackService",new Payment(id,"errorSerial"));
    }
}

Controller中添加请求处理

    //==================OpenFeign
    @Resource
    private PaymentService paymentService;

    @GetMapping(value = "/consumer/paymentSQL/{id}")
    @SentinelResource(value="paymentSQL",blockHandlerClass = BlockHandlers.class,blockHandler = "paymentSQLBlockHandler",fallbackClass = FallBacks.class,fallback = "paymentSQLFallBack")
    public CommonResult paymentSQL(@PathVariable Long id)
    {
        return paymentService.paymentSQL(id);
    }

主函数入口开启Feign客户端

@EnableFeignClients 

限流测试

触发限流后，blockException并没有被友好处理，而是直接抛出了Error页面！
找了好久原因，竟然是因为传入的参数 id 的类型不一致：
public String xxxBlockHandler(@PathVariable long id, BlockException exception){…}
实际上应该传入Long，而不是long。
在给定blockHandler之后，如果没有找到合适的方法供调用，并没有友好提示，有点坑的。

再次测试成功限流

熔断测试

停掉其它服务

访问后给出熔断降级提示

运行时异常测试

添加制造异常的语句

成功处理运行时异常