1、雪崩效应:
2、Hystrix是什么?
3、什么是服务熔断?
4、引入相关依赖:
<!-- hystrix -->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>
5、编写controller:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import com.atguigu.springcloud.entities.Dept;
import com.atguigu.springcloud.service.DeptService;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
@RestController
public class DeptController {
@Autowired
private DeptService service = null;
@RequestMapping(value = "/dept/get/{id}", method = RequestMethod.GET)
// 一旦调用服务方法失败并抛出了错误信息后,会自动调用@HystrixCommand标注好的fallbackMethod调用类中的指定方法
@HystrixCommand(fallbackMethod = "processHystrix_Get")
public Dept get(@PathVariable("id") Long id) {
Dept dept = this.service.get(id);
if (null == dept) {
throw new RuntimeException("该ID:" + id + "没有没有对应的信息");
}
return dept;
}
public Dept processHystrix_Get(@PathVariable("id") Long id) {
Dept dept = new Dept();
dept.setDeptno(id);
dept.setDname("该ID:" + id + "没有没有对应的信息,null--@HystrixCommand");
dept.setDb_source("no this database in MySQL");
return dept;
}
}
6、启动类开启注解(@EnableCircuitBreaker//对hystrixR熔断机制的支持):
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
@SpringBootApplication
@EnableEurekaClient //本服务启动后会自动注册进eureka服务中
@EnableDiscoveryClient //服务发现
@EnableCircuitBreaker//对hystrixR熔断机制的支持
public class DeptProvider8001_Hystrix_App
{
public static void main(String[] args)
{
SpringApplication.run(DeptProvider8001_Hystrix_App.class, args);
}
}