springcould中的熔断器hystrix与远程调用feign相结合，以及fallback不生效的问题

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已于 2023-07-04 14:41:40 修改

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于 2023-07-04 14:37:41 首次发布

本文链接：https://blog.youkuaiyun.com/c_xiao_dian_dian/article/details/131531596

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当我们学习完hystrix，首选想到的是它能不能结合起feign起到远程调用的作用，答案肯定是可以的。下面让我们一步一步来解析这整个过程：

一、创捷一个父项目springcould，在父项目里面创捷公共接口的子模块commons-interface，其目录结构如下

其中：

bean包是实体类包

client包是feign远程调用包

service包是所有提供者的service层接口

1.1 commons-interface模块的pom.xml的主要依赖

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </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>
        <!--客户端feign依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>

1.2创建一个实体类对象UserBean

@Data
@AllArgsConstructor
@NoArgsConstructor
public class UserBean implements Serializable {
    private Integer userId;
    private String userName;
    private Integer age;
}

1.3创建UserService接口

public interface UserService {
    UserBean getUser();
}

1.4创建Feign远程调用的UserClient接口

其中的@FeignClient中的value属性是提供者的微服务的名称，fallback属性是发生熔断回调执行的方法类

@FeignClient(value = "provider",fallback = UserClientFeignFallBack.class)//调用的服务名称
public interface UserClient {
    @GetMapping("user")
    UserBean getOne();
}

1.5创建发生熔断回调的UserClientFeignFallBack类

@Service
public class UserClientFeignFallBack implements UserClient {
    @Override
    public UserBean getOne() {
        UserBean userBean = new UserBean();
        userBean.setUserName("服务器正忙，请稍后重试");
        return userBean;
    }
}

二、在父项目里面创建提供者的子模块provide01，其目录结构如下：

其中：

controller包是提供者的控制层包

service包是提供者的服务层包

2.1provide01子模块的application.yml

server:
  port: 8081
spring:
  application:
    name: provider #服务的名称
  cloud:
    nacos:
      server-addr: localhost:8848

2.2provide01子模块的pom.xml

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!--统一的接口规范-->
        <dependency>
            <groupId>com.neuedu</groupId>
            <artifactId>commons-interface</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>

        <!-- nacos客户端依赖包 -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--nacos的配置管理依赖-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
        </dependency>
    </dependencies>

2.3在controller包创建UserController类

@RestController
@RequestMapping("user")
public class UserController {
    @Autowired
    private UserService service;

    @GetMapping
    public UserBean getOne(){
        return service.getUser();
    }
}

2.4在service包的impl包创建UserServiceImpl类

@Service
public class UserServiceImpl implements UserService {
    @Override
    public UserBean getUser() {
        return new UserBean(100,"张三",18);
    }
}

2.5provide01模块的Provider01Application 类

@SpringBootApplication
@EnableDiscoveryClient
public class Provider01Application {

    public static void main(String[] args) {
        SpringApplication.run(Provider01Application.class, args);
    }

}

三、在父项目里面创建用户消费者的子模块userconsumer01，其目录结构如下：

其中：

controller包是用户消费者的控制层

3.1userconsumer01子模块的application.yml

server:
  port: 8083
spring:
  application:
    name: consumer
  cloud:
    nacos:
      server-addr: localhost:8848
feign:
  client:
    config:
      default: #default是所有服务都开启，可以指定某个服务名称（provider）进行开启
        loggerLevel: FULL #开启日志
  hystrix:
    enabled: true  # feign中的熔断器hystrix是关闭的，需要手动打开
  httpclient:
    enabled: true #支持httpclient的开关
    max-connections: 200 #最大连接数
    max-connections-per-route: 50 #单个路径的最大连接数
  sentinel:
    enabled: true
#设定Hystrix熔断超时时间 ，理论上熔断时间应该大于总连接超时时间
hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 6000

3.2userconsumer01子模块的pom.xml

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- nacos客户端依赖包 -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>

        <!--统一的接口规范-->
        <dependency>
            <groupId>com.neuedu</groupId>
            <artifactId>commons-interface</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <!--客户端feign依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

        <!--引入httpclient依赖-->
        <dependency>
            <groupId>io.github.openfeign</groupId>
            <artifactId>feign-httpclient</artifactId>
        </dependency>

        <!-- 流量控制sentinel依赖-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
            <version>2.2.0.RELEASE</version>
        </dependency>
        <!--熔断器（断路器）-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>

    </dependencies>

3.3在controller包创建UserController类

@RestController
@RequestMapping("userConsumer")
public class UserController {

    @Autowired
    private UserClient userClient;

    @GetMapping("getOne")
    public UserBean getOne()
        return userClient.getOne();
    }

}

3.4userconsumer01模块的Userconsumer01Application 类

@SpringBootApplication
@EnableDiscoveryClient
@EnableCircuitBreaker  //开启熔断机制
@EnableFeignClients(basePackages = "com.neuedu.client") //开启客户端feign,指定访问的包,防止两个项目的路径出现不一致的问题
public class Userconsumer01Application {

    public static void main(String[] args) {
        SpringApplication.run(Userconsumer01Application.class, args);
    }

    @Bean
    public RestTemplate getTempalte(){
        return new RestTemplate();
    }
}

至此，springcould中的熔断器hystrix与远程调用feign相结合的全部代码实现过程到此完成，至于为什么会出现fallback不生效的问题，原因是在userconsumer01子模块的application.yml中忘记添加了如下代码：