Hystrix熔断器整合 - Feign实现服务容错

实战前需了解：https://blog.csdn.net/wanzijy/article/details/125041622
Hystrix熔断器整合 - 搭建项目：https://blog.csdn.net/wanzijy/article/details/125496651
Hystrix熔断器整合 - 请求缓存：https://blog.csdn.net/wanzijy/article/details/125512072
Hystrix熔断器整合 - 请求合并：https://blog.csdn.net/wanzijy/article/details/125579664
Hystrix熔断器整合 - 服务隔离之线程池隔离：https://blog.csdn.net/wanzijy/article/details/125630353
Hystrix熔断器整合 - 服务隔离之信号量隔离：https://blog.csdn.net/wanzijy/article/details/125826690
Hystrix熔断器整合 - 服务熔断和服务降级：https://blog.csdn.net/wanzijy/article/details/125826853
Hystrix熔断器整合 - Feign实现服务容错：https://blog.csdn.net/wanzijy/article/details/125985304
Hystrix熔断器整合 - 可视化界面三部曲：https://blog.csdn.net/wanzijy/article/details/126005452

1. 模块搭建

1.1 pom.xml

<dependencies>
	<dependency>
		<groupId>org.springframework.cloudgroupId>
		<artifactId>spring-cloud-starter-netflix-eureka-clientartifactId>
	dependency>
	<dependency>
		<groupId>org.springframework.cloudgroupId>
		<artifactId>spring-cloud-starter-openfeignartifactId>
	dependency>
	<dependency>
		<groupId>org.springframework.bootgroupId>
		<artifactId>spring-boot-starter-webartifactId>
	dependency>
	<dependency>
		<groupId>org.projectlombokgroupId>
		<artifactId>lombokartifactId>
 		<scope>providedscope>
	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>
dependencies>
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1.2 配置文件

spring:
  application:
    name: order-service-feign

server:
  port: 9091

eureka:
  instance:
    prefer-ip-address: true  #  是否使用 ip 地址注册
    instance-id: ${spring.cloud.client.ip-address}:${server.port}  #  ip:port
  client:
    service-url:  #  设置服务注册中心地址
      defaultZone: http://eureka01:8761/eureka/,http://eureka02:8762/eureka/
    register-with-eureka: true
    fetch-registry: true

feign:
  hystrix:
    enabled: true
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1.3 启动类

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class OrderServiceFeignApplication {
    public static void main(String[] args) {
        SpringApplication.run(OrderServiceFeignApplication.class, args);
    }
}
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1.4 pojo

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Order {
    private Integer id;
    private String orderNo;
    private String orderAddress;
    private Double totalPrice;
    private List<Product> productList;
}
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@Data
@AllArgsConstructor
@NoArgsConstructor
public class Product {
    private Integer id;
    private String productName;
    private Integer productNum;
    private Double productPrice;
}
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1.5 service

@FeignClient(value = "product-service", fallback = ProductServiceFallback.class)
public interface ProductService {
    @GetMapping("/product/list")
    List<Product> selectProductList();

    @GetMapping("/product/listByIds")
    List<Product> selectProductListByIds(@RequestParam("id") List<Integer> ids);

    @GetMapping("/product/{id}")
    Product selectProductListById(@PathVariable("id") Integer id);
}
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public interface OrderService {
    Order selectOrderById(Integer id);

    Order queryOrderById(Integer id);

    Order searchOrderById(Integer id);
}
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@Service
public class OrderServiceImpl implements OrderService{

    @Autowired
    private ProductService productService;

    @Override
    public Order selectOrderById(Integer id) {
        return new Order(id, "order-001", "中国", 22788D,
                productService.selectProductList());
    }

    @Override
    public Order queryOrderById(Integer id) {
        return new Order(id, "order-002", "中国", 11600D,
                productService.selectProductListByIds(Arrays.asList(1, 2)));
    }
    
    @Override
    public Order searchOrderById(Integer id) {
        return new Order(id, "order-003", "中国", 2666D,
                Arrays.asList(productService.selectProductListById(1)));
    }

}
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1.6 controller

@RestController
@RequestMapping("/order")
public class OrderController {

    @Autowired
    private OrderService orderService;

    @GetMapping("/{id}/product/list")  //  localhost:9091/order/1/product/list
    public Order selectOrderById(@PathVariable("id") Integer id) {
        return orderService.selectOrderById(id);
    }

    @GetMapping("/{id}/product/listByIds")  //  http://localhost:9091/order/1/product/listByIds
    public Order queryOrderById(@PathVariable("id") Integer id) {
        return orderService.queryOrderById(id);
    }

    @GetMapping("/{id}/product")  //  http://localhost:9091/order/1/product
    public Order searchOrderById(@PathVariable("id") Integer id) {
        return orderService.searchOrderById(id);
    }

}
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1.7 fallback 包

@Component
public class ProductServiceFallback implements ProductService {

    @Override
    public List<Product> selectProductList() {
        return Arrays.asList(
                new Product(1, "托底数据-华为手机", 1, 5800D),
                new Product(2, "托底数据-联想笔记本", 1, 6888D),
                new Product(3, "托底数据-小米平板", 5, 2020D)
        );
    }

    @Override
    public List<Product> selectProductListByIds(List<Integer> ids) {
        List<Product> products = new ArrayList<>();
        ids.forEach(id -> products.add(new Product(id, "托底数据-电视机" + id, 1, 8650D)));
        return products;
    }

    @Override
    public Product selectProductListById(Integer id) {
        return new Product(id, "托底数据-冰箱", 1, 2666D);
    }

}
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2. 简介

Feign 实现容错，主要是通过 @FeignClient 注解实现
该注解下有一个参数 fallback ，值填上远程调用实现接口的实现类的 class
所有发生容错方法的托底数据都在远程调用接口的实现类上

远程调用接口：ProductService
远程调用接口实现类：ProductServiceFallback

3. 测试

上述有3个接口，在这随意访问一个： http://localhost:9091/order/1/product/listByIds

此时关掉 product-service 模块，再次访问

4. 修改上述的容错，使其打印在控制台上

4.1 在 fallback 包下新建一个类

@Component
public class ProductServiceFallbackFactory implements FallbackFactory<ProductService> {

    Logger logger = LoggerFactory.getLogger(ProductServiceFallbackFactory.class);

    @Override
    public ProductService create(Throwable cause) {
        return new ProductService() {
            @Override
            public List<Product> selectProductList() {
                logger.error("ProductService 服务的 selectProductList 方法出现异常，异常信息如下：" + cause);

                return Arrays.asList(
                        new Product(1, "托底数据-华为手机", 1, 5800D),
                        new Product(2, "托底数据-联想笔记本", 1, 6888D),
                        new Product(3, "托底数据-小米平板", 5, 2020D)
                );
            }

            @Override
            public List<Product> selectProductListByIds(List<Integer> ids) {
                logger.error("ProductService 服务的 selectProductListByIds 方法出现异常，异常信息如下：" + cause);

                List<Product> products = new ArrayList<>();
                ids.forEach(id -> products.add(new Product(id, "托底数据-电视机" + id, 1, 8650D)));
                return products;
            }

            @Override
            public Product selectProductListById(Integer id) {
                logger.error("ProductService 服务的 selectProductListById 方法出现异常，异常信息如下：" + cause);

                return new Product(id, "托底数据-冰箱", 1, 2666D);
            }
        };
    }

}
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4.2 修改 ProductService

@FeignClient(value = "product-service", fallbackFactory = ProductServiceFallbackFactory.class)
public interface ProductService {

    @GetMapping("/product/list")
    List<Product> selectProductList();

    @GetMapping("/product/listByIds")
    List<Product> selectProductListByIds(@RequestParam("id") List<Integer> ids);

    @GetMapping("/product/{id}")
    Product selectProductListById(@PathVariable("id") Integer id);

}
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4.3 测试

重复第3节的测试，然后看其控制台