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