一、Hystrix是什么
Hystrix是一个用于处理分布式系统的延迟和容错的开源库，在分布式系统里，许多依赖不可避免的会调用失败，比如超时、异常等，Hystrix能够保证在一个依赖出问题的情况下，不会导致整体服务失败，避免级联故障，以提高分布式系统的弹性。
二、Hystrix能做什么
1、服务降级
服务器忙，请稍后再试，不让客户端等待并立刻返回一个友好提示fallback。
2、服务熔断
类比保险丝达到最大服务访问后，直接拒绝访问，拉闸限电，然后调用服务降级的方法并返回友好提示。
3、服务限流
秒杀高并发等操作，严禁一窝蜂拥挤，大家排队，一秒钟N个，有序进行。
三、Hystrix怎么用
1、创建模块
创建普通maven模块cloud-provider-hystrix-payment8001
2、修改pom文件
<?xml version="1.0" encoding="UTF-8"?> <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"> <parent> <artifactId>cloud</artifactId> <groupId>com.shang.cloud</groupId> <version>1.0-SNAPSHOT</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>cloud-provider-hystrix-payment8001</artifactId> <dependencies> <!--hystrix--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-hystrix</artifactId> </dependency> <!--eureka client--> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <!--web--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity --> <groupId>com.shang.cloud</groupId> <artifactId>cloud-api-commons</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> <optional>true</optional> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <properties> <maven.compiler.source>8</maven.compiler.source> <maven.compiler.target>8</maven.compiler.target> </properties> </project>
3、编写yml文件
server: port: 8001 spring: application: name: cloud-provider-hystrix-payment eureka: client: register-with-eureka: true fetch-registry: true service-url: #集群版 #defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka #单机版 defaultZone: http://eureka7001.com:7001/eureka
4、编写主启动类
@SpringBootApplication @EnableEurekaClient public class PaymentHystrixMain8001 { public static void main(String[] args) { SpringApplication.run(PaymentHystrixMain8001.class, args); } }
5、编写逻辑代码
（1）service
@Service public class PaymentService { /** * 正常访问，肯定OK * @param id * @return */ public String paymentInfo_OK(Integer id) { return "线程池: "+Thread.currentThread().getName()+" paymentInfo_OK,id: "+id+"\t"+"O(∩_∩)O哈哈~"; } public String paymentInfo_TimeOut(Integer id) { //int age = 10/0; try { TimeUnit.MILLISECONDS.sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); } return "线程池: "+Thread.currentThread().getName()+" id: "+id+"\t"+"O(∩_∩)O哈哈~"+" 耗时(秒): "; } }
2）controller
@RestController @Slf4j public class PaymentController { @Autowired private PaymentService paymentService; @Value("${server.port}") private String serverPort; @GetMapping(value = "/payment/hystrix/ok/{id}") public String paymentInfo_OK(@PathVariable(value = "id") Integer id){ String result = paymentService.paymentInfo_OK(id); log.info("=======result:"+result); return result; } @GetMapping(value = "/payment/hystrix/timeout/{id}") public String paymentInfo_TimeOut(@PathVariable(value = "id") Integer id){ String result = paymentService.paymentInfo_TimeOut(id); log.info("=======result:"+result); return result; } }
6、运行测试
在地址栏中输入
http://localhost:8001/payment/hystrix/ok/1
这是我们编写的正常服务
能够正常访问
再访问 http://localhost:8001/payment/hystrix/timeout/1
这是我们模拟的超时服务
3秒后，成功访问。
