springcloudgateway hystrix 获取异常信息(springcloud hystrix怎么触发熔断)

本示例主要介绍 Spring Cloud 系列中的 Eureka,如何使用Hystrix熔断器容错保护我们的应用程序。

在微服务架构中,系统被拆分成很多个服务单元,各个服务单元的应用通过 HTTP 相互调用、依赖,在某个服务由于网络或其他原因自身出现故障、延迟时,调用方也会出现延迟。若调用方请求不断增加,可能会形成任务积压,最终导致调用方服务瘫痪,服务不可用现象逐渐放大。

解决方案

Spring Cloud Hystrix 是一个专用于服务熔断处理的开源项目,实现了一系列服务保护措施,当依赖的服务方出现故障不可用时,hystrix实现服务降级、服务熔断等功能,对延迟和故障提供强大的容错能力,从而防止故障进一步扩大。

Hystrix 主要作用介绍

  • 保护和控制底层服务的高延迟和失效对上层服务的影响。
  • 避免复杂分布式中服务失效的雪崩效应。在大型的分布式系统中,存在各种复杂的依赖关系。如果某个服务失效,很可能会对其他服务造成影响,形成连锁反应。
  • 快速失效和迅速恢复。以Spring为例,一般在实现controller的时候,都会以同步的逻辑调用依赖的服务。如果服务失效,而且没有客户端失效机制,就会导致请求长时间的阻塞。如果不能快速的发现失效,而就很难通过高可用机制或者负载均衡实现迅速的恢复。
  • 实现服务降级。这一点是从用户体验来考虑的,一个预定义默认返回会比请求卡死或者500好很多。
  • 实现了服务监控、报警和运维控制。Hystrix Dashboard和Turbine可以配合Hystrix完成这些功能。

Hystrix 主要特性:

  • 服务熔断
  • Hystrix 会记录各个服务的请求信息,通过 成功、失败、拒绝、超时 等统计信息判断是否打开断路器,将某个服务的请求进行熔断。一段时间后切换到半开路状态,如果后面的请求正常则关闭断路器,否则继续打开断路器。
  • 服务降级
  • 服务降级是请求失败时的后备方法,故障时执行降级逻辑。
  • 线程隔离
  • Hystrix 通过线程池实现资源的隔离,确保对某一服务的调用在出现故障时不会对其他服务造成影响。

代码实现

创建三个项目来完成示例,分别为:服务注册中心hystrix-eureka-server,服务提供者hystrix-service-provider,服务消费者hystrix-service-consumer

1.创建hystrix-eureka-server服务注册中心

pom.xml配置

<?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"> <modelVersion>4.0.0</modelVersion> <groupId>com.easy</groupId> <artifactId>hystrix-eureka-server</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>hystrix-eureka-server</name> <description>Demo project for Spring Boot</description> <parent> <artifactId>cloud-hystrix</artifactId> <groupId>com.easy</groupId> <version>1.0.0</version> </parent> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project>

application.yml配置文件

server: port: 8761spring: application: name: eureka-servereureka: instance: hostname: localhost # eureka 实例名称 client: register-with-eureka: false # 不向注册中心注册自己 fetch-registry: false # 是否检索服务 service-url: defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/ # 注册中心访问地址

HystrixEurekaServerApplication.java启动类

package com.easy.eurekaServer;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;@EnableEurekaServer@SpringBootApplicationpublic class HystrixEurekaServerApplication { public static void main(String[] args) { SpringApplication.run(HystrixEurekaServerApplication.class, args); }}

2.创建hystrix-service-provider服务提供者

pom.xml配置

<?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"> <modelVersion>4.0.0</modelVersion> <groupId>com.easy</groupId> <artifactId>hystrix-service-provider</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>hystrix-service-provider</name> <description>Demo project for Spring Boot</description> <parent> <artifactId>cloud-hystrix</artifactId> <groupId>com.easy</groupId> <version>1.0.0</version> </parent> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project>

application.yml配置文件

spring: application: name: hystrix-service-providereureka: client: service-url: defaultZone: http://localhost:8761/eureka/ # 实例一server: port: 8081

HelloController.java提供一个hello接口

package com.easy.serviceProvider.web;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class HelloController { @GetMapping("hello") public String hello(@RequestParam String p1, @RequestParam String p2) throws Exception {// 用来测试服务超时的情况// int sleepTime = new Random().nextInt(2000);// System.out.println("hello sleep " + sleepTime);// Thread.sleep(sleepTime); return "hello, " + p1 + ", " + p2; }}

最后贴上启动类HystrixServiceProviderApplication.java

package com.easy.serviceProvider;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.client.discovery.EnableDiscoveryClient;@EnableDiscoveryClient@SpringBootApplicationpublic class HystrixServiceProviderApplication { public static void main(String[] args) { SpringApplication.run(HystrixServiceProviderApplication.class, args); }}

3.创建hystrix-service-consumer服务消费者

pom.xml配置

<?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"> <modelVersion>4.0.0</modelVersion> <groupId>com.easy</groupId> <artifactId>hystrix-service-consumer</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>hystrix-service-consumer</name> <description>Demo project for Spring Boot</description> <parent> <artifactId>cloud-hystrix</artifactId> <groupId>com.easy</groupId> <version>1.0.0</version> </parent> <dependencies> <!-- eureka 客户端 --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId> </dependency> <!-- ribbon --> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-ribbon</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-hystrix</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project>

application.yml配置文件

spring: application: name: hystrix-eureka-servereureka: client: service-url: defaultZone: http://localhost:8761/eureka/hystrix: command: default: execution: isolation: thread: timeoutInMilliseconds: 1000 # 默认超时时间

相关代码

异常处理类NotFallbackException.java

package com.easy.serviceConsumer.exception;public class NotFallbackException extends Exception {}

服务层HelloService.java

package com.easy.serviceConsumer.service;import com.easy.serviceConsumer.exception.NotFallbackException;import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import org.springframework.web.client.RestTemplate;@Servicepublic class HelloService { @Autowired RestTemplate restTemplate; private static final String HELLO_SERVICE = "http://hystrix-service-provider/"; @HystrixCommand(fallbackMethod = "helloFallback", ignoreExceptions = {NotFallbackException.class} , groupKey = "hello", commandKey = "str", threadPoolKey = "helloStr") public String hello(String p1, String p2) { return restTemplate.getForObject(HELLO_SERVICE + "hello?p1=" + p1 + "&p2=" + p2, String.class); } private String helloFallback(String p1, String p2, Throwable e) { System.out.println("class: " + e.getClass()); return "error, " + p1 + ", " + p2; }}

控制器ConsumerController.java

package com.easy.serviceConsumer.web;import com.easy.serviceConsumer.service.HelloService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class ConsumerController { @Autowired HelloService helloService; @GetMapping("hello") public String hello(@RequestParam String p1, @RequestParam String p2) { System.out.println("hello"); return helloService.hello(p1, p2); }}

4.启动类HystrixServiceConsumerApplication.java

package com.easy.serviceConsumer;import org.springframework.boot.SpringApplication;import org.springframework.cloud.client.SpringCloudApplication;import org.springframework.cloud.client.loadbalancer.LoadBalanced;import org.springframework.context.annotation.Bean;import org.springframework.web.client.RestTemplate;@SpringCloudApplicationpublic class HystrixServiceConsumerApplication { @Bean @LoadBalanced RestTemplate restTemplate() { return new RestTemplate(); } public static void main(String[] args) { SpringApplication.run(HystrixServiceConsumerApplication.class, args); }}

使用示例

分别运行3个服务,HystrixEurekaServerApplication.java(服务注册中心),HystrixServiceProviderApplication.java(服务提供者),HystrixServiceConsumerApplication.java(服务消费者)

  • 1.访问 http://localhost:8080/hello?p1=a&p2=b ,正常情况下响应为 hello, a, b
  • 2.关闭 hystrix-service-provider 或在 sleepTime 超过 1000ms 时,访问 http://localhost:8080/hello?p1=a&p2=b,执行降级逻辑,返回 error, a, b

作者:云天

原文:https://www.cnblogs.com/tqlin/p/11653188.html

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