Hystrix熔断降级

目录

项目实战

 Hystrix技术点

---

开门见山，和Sentinel一样解决了我们的项目中因为级联失败而导致服务雪崩现象

解决：

1.流量控制

进行限流，QPS

2.缓存

对可能频繁访问的数据加入缓存中，减少数据库的压力

3.服务熔断降级

服务接口拒绝服务，本质就是我们的断路器限制我们的服务请求访问

项目实战

@EnableCircuitBreaker：启用断路器

@EnableHystrixDashboard：启用Hystrix 

@EnableDiscoveryClient
@EnableCircuitBreaker//启用断路器
@SpringBootApplication
@SpringCloudApplication
@EnableHystrixDashboard
public class MicroserviceProviderHystrixApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(MicroserviceProviderHystrixApplication.class, args);
    }
 
}

1.依赖 

<dependencies>
        
        <dependency>
            <groupId>com.baomidougroupId>
            <artifactId>mybatis-plus-boot-starterartifactId>
            <version>3.4.2version>
        dependency>
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-hystrixartifactId>
        dependency>
        
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-openfeignartifactId>
        dependency>
 
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboardartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintagegroupId>
                    <artifactId>junit-vintage-engineartifactId>
                exclusion>
            exclusions>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
        dependency>
    dependencies>

2.mapper

@Mapper
public interface ProductMapper extends BaseMapper {
 
}

3.service

在业务接口上指定异常回退

//在业务接口上指定异常处理类
@FeignClient(name = "microservice-provider-hystrix",fallbackFactory = IProductClientServiceFallbackFactory.class)
public interface IProductService extends IService {
 
    Product getProductById(Integer id);
 
}

@Service
public class ProductService extends ServiceImpl implements IProductService{
 
 
    @Override
    public Product getProductById(Integer id) {
        Product product = baseMapper.selectById(id);
        return product;
    }
}

3.控制层

@HystrixCommand(fallbackMethod="xxx")：当方法抛出异常进行熔断降级处理方法

@RestController
public class ProductController {
 
    @Autowired
    private ProductService productService;
 
    @GetMapping("{id}")
    @HystrixCommand(fallbackMethod ="errorCallBack")
    public Object get(@PathVariable("id") Integer id){
        Product p = productService.getProductById(id);
        if(p==null){
            throw new RuntimeException("查无此商品");
        }
        return new JsonResult(200,p);
    }
 
    /**
     * 熔断降级的方法
     */
    public Object errorCallBack(@PathVariable("id") Integer id){
        return id+"不存在,error";
    }
 
 
}

4.FailBackFactory实现类

这个需要导入feign，在FeiginClient中，可以制定fallback实现服务不可以用时自动调用fallback指定处理方法

@Component
public class IProductClientServiceFallbackFactory implements FallbackFactory {
    @Override
    public IProductService create(Throwable throwable) {
        //回退机制
        return new IProductService() {
            @Override
            public Product getProductById(Integer id) {
                Product product = new Product();
                product.setCategoryId(999999);
                product.setPrice(99999999L);
                return product;
            }
 
            @Override
            public boolean saveBatch(Collection entityList, int batchSize) {
                return false;
            }
 
            @Override
            public boolean saveOrUpdateBatch(Collection entityList, int batchSize) {
                return false;
            }
 
            @Override
            public boolean updateBatchById(Collection entityList, int batchSize) {
                return false;
            }
 
            @Override
            public boolean saveOrUpdate(Product entity) {
                return false;
            }
 
            @Override
            public Product getOne(Wrapper queryWrapper, boolean throwEx) {
                return null;
            }
 
            @Override
            public Map getMap(Wrapper queryWrapper) {
                return null;
            }
 
            @Override
            public  V getObj(Wrapper queryWrapper, Functionsuper Object, V> mapper) {
                return null;
            }
 
            @Override
            public BaseMapper getBaseMapper() {
                return null;
            }
 
            @Override
            public Class getEntityClass() {
                return null;
            }
        };
    }
}

 Hystrix技术点

1.快速失败并且迅速恢复

2.优雅降级

3.实施实时监控

将外部服务包装到HystrixCommand对象中，并单独线程中处理

服务错误百分比超过了阈值，熔断器开关自动打开，一段时间内停止对该服务的所有请求。

(37条消息) 微服务熔断机制 Hystrix_STRANG-P的博客-CSDN博客