SpringCould-------使用Hystrix 实现断路器进行服务容错保护

消费：

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.sam</groupId>
    <artifactId>hello-consumer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.1.RELEASE</version>
    </parent>

    <properties>
        <javaVersion>1.8</javaVersion>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.SR6</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>

    </dependencyManagement>

    <dependencies>
        <!-- 引入eureka 客户端依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <!-- 引入ribbon 依赖 ，用来实现负载均衡，我们这里只是使用，先不作其他介绍-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>4.3.6.RELEASE</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- 引入hystrix 依赖 ，用来实现服务容错保护-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-hystrix</artifactId>
        </dependency>
    </dependencies>
</project>

启动类：

/*@SpringBootApplication +
@EnableDiscoveryClient+
@EnableCircuitBreaker
  =  @SpringCloudApplication */

@SpringCloudApplication
public class CustomerApplication {
    //@Bean 应用在方法上，用来将方法返回值设为为bean
    @Bean
    @LoadBalanced  //@LoadBalanced实现负载均衡
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

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

}

service:

@Service
public class ConsumerService {

    @Autowired
    RestTemplate restTemplate;

    @HystrixCommand(fallbackMethod = "errorMsg")
    public String consumer() {

        return restTemplate.getForObject("http://hello-service/hello", String.class);
    }

       /**
        * 由 @HystrixCommand(fallbackMethod = "errorMsg")
        * 可知 在起多个服务时，如果其中一个服务宕机，则会调用 errorMsg()
        * 方法； 相比在不加@EnableCircuitBreaker断路器，的包500d的错
        */

    public String errorMsg() {
        return "error!!!";
    }
}

controller:

@RestController
public class ConsumerController {

    //这里注入的restTemplate就是在com.sam.ConsumerApp中通过@Bean配置的实例
    /*@Autowired
    RestTemplate restTemplate;*/

    @Autowired
    ConsumerService consumerService;

    @RequestMapping("/consumer")
    public String helloConsumer() {
        //调用hello-service服务，注意这里用的是服务名，而不是具体的ip+port
      //  return restTemplate.getForObject("http://hello-service/hello", String.class);
        return consumerService.consumer();
    }
}