SpringCloud整合Hystrix的两种方式

一、准备工作

1. 新建Eureka注册中心模块（单机）

① 引入依赖

<dependencies>
    <!-- web 启动器 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- eureka server端 -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
    </dependency>
</dependencies>

② application.properties配置

# 设置spring应用命名，可以自定义，非必要
spring.application.name=eureka-server
# 设置Eureka Server WEB控制台端口，自定义
server.port=8761
#是否将自己注册到Eureka-Server中，默认的为true
eureka.client.register-with-eureka=false
#是否从Eureka-Server中获取服务注册信息，默认为true
eureka.client.fetch-registry=false

③ 启动eureka

@EnableEurekaServer
@SpringBootApplication
public class EurekaApplication {
    public static void main(String[] args) {
        SpringApplication.run(EurekaApplication.class, args);
    }
}

执行main方法，访问 http://localhost:8761 查看。

2. 新建服务接口模块api-service

这个很简单，只有接口声明。

public interface UserService {

    Map<String,Object> getUser(Integer id);
}

二、Ribbon中使用熔断器

1. 新建服务提供者模块

① 引入依赖

<dependencies>
    <!-- web 启动器 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- eureka client -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <!--接口依赖-->
    <dependency>
        <groupId>com.example</groupId>
        <artifactId>api-service</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </dependency>
</dependencies>

② application.properties配置

spring.application.name=userService
server.port=8666
eureka.instance.instance-id=user-service
#注册中心地址
eureka.client.serviceUrl.defaultZone=http://127.0.0.1:8761/eureka/
#访问信息可以使用IP地址
eureka.instance.prefer-ip-address=true

③ 启动类

@EnableDiscoveryClient
@SpringBootApplication
public class AppService {
    public static void main(String[] args) {
        SpringApplication.run(AppService.class, args);
    }
}

④ 服务接口实现

@Service
public class UserServiceImpl implements UserService {
    @Override
    public Map<String, Object> getUser(Integer id) {
        Map<String, Object> data = new HashMap<>();
        data.put("id", Math.random() + "-" + id);
        data.put("name", "test name");
        data.put("age", 20);
        return data;
    }
}

⑤ 对外访问controller

@RestController
public class UserController {

    @Autowired
    UserService userService;

    @RequestMapping("/getUser/{id}")
    public Map<String, Object> getUser(@PathVariable(value = "id") Integer id){
        return userService.getUser(id);
    }
}

2. 新建消费者模块

① 引入依赖

<dependencies>
    <!-- web 启动器 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- eureka client -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <!-- ribbon -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
    </dependency>
    <!-- 整合hystrix -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
    </dependency>
</dependencies>

② application.properties

spring.application.name=userServiceConsumer
server.port=8777
eureka.instance.instance-id=user-service-consumer
eureka.client.serviceUrl.defaultZone=http://127.0.0.1:8761/eureka/
#访问信息可以使用IP地址
eureka.instance.prefer-ip-address=true

③ 启动类

@EnableHystrix //在启动类上添加@EnableHystrix注解开启Hystrix的熔断器功能。
@EnableEurekaClient
@SpringBootApplication
public class RibbonConsumerApplication {

    //当添加@LoadBalanced注解，就代表启动Ribbon,进行负载均衡
    @LoadBalanced
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

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

}

④ controller

@RestController
@RequestMapping("/hystrix/consumer")
public class HystrixConsumerController {

    @Autowired
    private RestTemplate restTemplate;

    /**
     * 调用 user微服务
     */
    @HystrixCommand(fallbackMethod = "getDefaultUser")
    @GetMapping("getUser")
    public String getUser(Integer id) {
        String url = String.format("http://%s/getUser/" + id, "userService");
        return restTemplate.getForObject(url, String.class);
    }

    public String getDefaultUser(Integer id) {
        System.out.println("熔断，默认回调函数");
        return "{"id":-1,"name":"熔断用户","age":"21"}";
    }
}

⑤ 访问：http://localhost:8777/hystrix/consumer/getUser?id=7，可以正常访问，然后停掉服务，还会发现进入熔断操作。

三、Feign中使用熔断器