Kite的学习历程SpringCloud之Hystrix服务降级

Kite学习历程的第二十三天

Hystrix服务降级

1. 创建Hystrix服务器端cloud-provider-hystrix-payment-8001

1.1 修改pom.xml文件

记得引入：spring-cloud-starter-netflix-hystrix依赖

<?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>demo01cloud</artifactId>
        <groupId>cn.kitey.spring</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-provider-hystrix-payment-8001</artifactId>


    <dependencies>
        <!--引入hystrix-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!--引入自己创建的entities包-->
        <dependency>
            <groupId>cn.kitey.spring</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--监控-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <!--热部署-->
        <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>

</project>

1.2 创建application.yml配置文件

server:
  port: 8001

spring:
  application:
    name: cloud-provider-hystrix-payment

eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      #就在一个注册中心进行注册
      defaultZone: http://eureka7001.com:7001/eureka

1. 3 创建主启动类

注意添加注解：
@EnableCircuitBreaker： 用于服务降级

package cn.kitey.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class PaymentHystrixMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentHystrixMain8001.class, args);
    }
}

1.4 创建service 业务层

三个方法：

1. 正常的方法
2. 设置了超时，并使用@HystrixCommand，设置了服务降级
3. 被方法二指定的的服务降级方法

package cn.kitey.springcloud.service;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
public class PaymentService {
    /**
     * 正常访问的操作
     * @param id
     * @return
     */
    public String paymentInfo_OK(Long id){
        return "线程池:  " + Thread.currentThread().getName() +
                "   paymentInfo_OK.id: " + id;
    }

    /**
     * 超时
     * @param id
     * @return
     */
    @HystrixCommand(
            //启用服务降级
            fallbackMethod = "paymentInfo_TimeOutHandler",
            //设置该方法的超时时间限制
            commandProperties = {@HystrixProperty(
                    name = "execution.isolation.thread.timeoutInMilliseconds",
                    value = "3000")}
    )
    public String paymentInfo_TimeOut(Long id){
        int timeNumber = 2000;
        try {
            //程序休眠3秒中
            TimeUnit.MILLISECONDS.sleep(timeNumber);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "线程池:  " + Thread.currentThread().getName() +
                "   paymentInfo_TimeOut.id: " + id + "   程序耗时"+ timeNumber+"毫秒钟";
    }

    /**
     * 服务降级执行方法
     * @param id
     * @return
     */
    public String paymentInfo_TimeOutHandler(Long id){
        return "线程池:  " + Thread.currentThread().getName() +
                "   paymentInfo_OK.id: " + id + "\t" + "服务降级后的执行方法";
    }

}

1.5 controller 控制类创建

提供访问地址，调用service方法

package cn.kitey.springcloud.contrller;

import cn.kitey.springcloud.service.PaymentService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

@RestController
@Slf4j
public class PaymentController {
    @Resource
    private PaymentService paymentService;

    @Value("@{server.port}")
    private String serverPort;

    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Long id){
        String info_ok = paymentService.paymentInfo_OK(id);
        log.info("------result:" + info_ok);
        return info_ok;
    }

   @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Long id){
        String info_ok = paymentService.paymentInfo_TimeOut(id);
        log.info("------result:" + info_ok);
        return info_ok;
    }

}

2 进行测试

1. 首先访问正常的：

http://localhost:8001/payment/hystrix/ok/1
2 首先设置
服务器等待时间3000毫秒大于方法的延迟时间2000毫秒进行访问

访问地址：
http://localhost:8001/payment/hystrix/timeout/1

3 设置方法延迟时间为5000 毫秒大于3000 毫秒

访问地址：
http://localhost:8001/payment/hystrix/timeout/1

这时就会执行服务降级设置的方法，避免程序出现错误页面