1 spring cloud整合Hystrix
Hystrix主要用来保护调用者这一方的服务，所以Eureka服务器和服务提供的代码和第一篇文章中相同，只需要修改服务调用者的代码即可。
创建一个spring boot项目用于服务调用，pom文件中增加Hystrix依赖如下：
<dependency
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
在启动类上，加入熔断器的注解@EnableCircuitBreaker
@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class ConSumerApp {
@Bean
@LoadBalanced
public RestTemplate getRestTemplate() {
return new RestTemplate();
}
public static void main(String[] args) {
new SpringApplicationBuilder(ConSumerApp.class)
.web(true).run(args);
}
}
创建一个服务类，用于编写Hystrix命令。使用注解@HystrixCommand表明getMember方法是一个Hystrix命令
- fallbackMethod参数指名回退方法；
- commandProperties参数用来配置命令，本例中配置超时时间为1秒;
- threadPoolProperties参数用来配置线程池，本例中配置线程池并发数为2。
@Service
//@DefaultProperties(defaultFallback = "getMemberFallback")
public class MemberService {
@Autowired
private RestTemplate restTpl;
@HystrixCommand(fallbackMethod = "getMemberFallback",
commandProperties = {
@HystrixProperty(name = "execution.isolation
.thread.timeoutInMilliseconds", value = "1000")
}, threadPoolProperties = {
@HystrixProperty(name = "coreSize", value = "2")
})
public Member getMember(Integer id) {
try {
Thread.sleep(2000);
} catch (Exception e) {
}
Member member = restTpl.getForObject(
"http://spring-hy-member/member/{id}", Member.class, id);
return member;
}
public Member getMemberFallback(Integer id) {
Member m = new Member();
m.setId(1);
m.setName("error member");
return m;
}
}
下面编写测试类，由于设置超时时间为1秒，故会执行回退方法。
@RestController
public class TestController {
@Autowired
private MemberService memberService;
@RequestMapping(value = "/router", method = RequestMethod.GET,
produces = MediaType.APPLICATION_JSON_VALUE)
public Member router() {
return memberService.getMember(1);
}
}
2 Hystrix 监控
为服务调用者加入Actuator依赖，可以对服务调用者的健康情况进行实时监控。
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
<version>1.5.3.RELEASE</version>
</dependency>
然后新建一个监控spring boot项目，pom文件内容如下：
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Dalston.SR1</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix-dashboard</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
<version>1.5.3.RELEASE</version>
</dependency>
</dependencies>
启动类代码如下：
@SpringBootApplication
@EnableHystrixDashboard
public class DashboardApp {
public static void main(String[] args) {
new SpringApplicationBuilder(DashboardApp.class).properties("server.port=8082").run(args);
}
}
访问项目地址：http://localhost:8082/hystrix，显示监控页面
image.png
输入要监控的项目地址：http://localhost:8081/hystrix.stream，能够看到该项目的命令调用情况。
image.png
第一排Circuit为熔断器使用情况；第二排为线程池使用情况。
