hystrix主要作用在服务消费者，进行应用的保护，当请求的服务请求超时时，做出相应的处理，避免客户端一直进行请求等待，避免在高并发的情况出现服务器死机（请求过多，内存不足）
接下来的通过一个案例对hystrix的使用进行说明，案例完成的功能：
服务消费者根据Id调用服务提供者的接口，获取User表单的对应的记录，若请求超时则返回id为-1的User记录
一、基于Ribbon
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
<mybatis-spring-boot.version>1.2.0</mybatis-spring-boot.version>
<mysql-connector.version>5.1.39</mysql-connector.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
<version>1.3.5.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
<version>1.3.5.RELEASE</version>
</dependency>
</dependencies>
2、application.yml
server:
port: 8089
spring:
application:
name: customer-user
eureka:
client:
serviceUrl:
defaultZone: http://user:zj123@localhost:8761/eureka
instance:
prefer-ip-address: true
instance-id: ${spring.application.name}:${spring.cloud.client.ipAddress}:${spring.application.instance_id:${server.port}}
provider-user:
ribbon:
NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule
3、Controller调用类
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.zhuojing.bean.User;
@RestController
public class UserController {
@Autowired
private RestTemplate restTemplate;
@GetMapping(value="/simple/{id}",produces=MediaType.APPLICATION_JSON_VALUE+";charset=utf-8")
@HystrixCommand(fallbackMethod = "findByIdFallback")
public User findUserById(@PathVariable Long id){
//服务提供者地址 PROVIDER-USER
return this.restTemplate.getForObject("http://PROVIDER-USER/simple/"+id, User.class);
}
/**
* 断路器模式，当请求的消费者provider-user超时的情况下，就会直接调用此方法，此方法的参数和返回类型必须和findUserById方法一致，请求超时时间为1秒
* @param id
* @return
*/
public User findByIdFallback(Long id){
User user = new User();
user.setId(0L);
return user;
}
}
hystrix的默认的超时时间为1秒，若自定hystrix超时时间有一下两种方式
a、@HystrixCommand注解配置
@HystrixCommand(fallbackMethod = "findByIdFallback",commandProperties = {
@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "3000")
})
b、在application.yml配置
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 5000
4、启动类
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.FilterType;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class AppCusRibbonPropertiesTest {
@Bean
@LoadBalanced
public RestTemplate restTemplate(){
return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(AppCusRibbonPropertiesTest.class, args);
}
}
二、dashboard的使用
1、pom.xml
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
<version>1.3.5.RELEASE</version>
</dependency>
</dependencies>
2、application.yml
server:
port: 8030
3、启动类
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
@EnableHystrixDashboard
@SpringBootApplication
public class DashboardApplication {
public static void main(String[] args) {
SpringApplication.run(DashboardApplication.class, args);
}
}
启动后访问：http:/ /localhost:8030/hystrix 进入首页，在地址栏上输入http:/ /localhost:8089/hystrix.stream（hystrix.stream）进行监控，在使用了hystrix的服务调用后才有数据。
三、Turbine的使用，Turbine是对微服务集群的监听
1、pom.xml
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-turbine</artifactId>
<version>1.3.5.RELEASE</version>
</dependency>
</dependencies>
2、application.yml
server:
port: 8031
spring:
application:
name: microservice-hystrix-turbine
eureka:
client:
serviceUrl:
defaultZone: http://user:zj123@localhost:8761/eureka
instance:
prefer-ip-address: true
turbine:
aggregator:
clusterConfig: default #默认defualt，只有一个服务时候可以写服务名称的大写CUSTOMER-USER
appConfig: customer-user
clusterNameExpression: "'default'"
3、启动类
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.turbine.EnableTurbine;
@EnableTurbine
@SpringBootApplication
public class TurbineApplication {
public static void main(String[] args) {
SpringApplication.run(TurbineApplication.class, args);
}
}
hystrix 主页面中将localhost:8031/turbine.stream?cluster=CUSTOMER-USER填入，便可进行数据的图像化。
