SpringCloud微服務(wù)框架Hystrix服務(wù)熔斷

Springcloud框架的Hystrix負(fù)載均衡

相關(guān)概念

Hystrix是一個(gè)用于處理分布式系統(tǒng)的延遲和容錯(cuò)的開(kāi)源庫(kù)，在分布式系統(tǒng)里，許多依賴不可避免的會(huì)調(diào)用失敗，比如超時(shí)、異常等，Hystrix能夠保證在一個(gè)依賴出問(wèn)題的情況下，不會(huì)導(dǎo)致整體服務(wù)失敗，避免級(jí)聯(lián)故障，以提高分布式系統(tǒng)的彈性?！皵嗦菲鳌北旧硎且环N開(kāi)關(guān)裝置，當(dāng)某個(gè)服務(wù)單元發(fā)生故障之后，通過(guò)斷路器的故障監(jiān)控（類(lèi)似熔斷保險(xiǎn)絲），向調(diào)用方返回一個(gè)符合預(yù)期的、可處理的備選響應(yīng)（FallBack），而不是長(zhǎng)時(shí)間的等待或者拋出調(diào)用方無(wú)法處理的異常，這樣就保證了服務(wù)調(diào)用方的線程不會(huì)被長(zhǎng)時(shí)間、不必要地占用，從而避免了故障在分布式系統(tǒng)中的蔓延，乃至雪崩。

Hystrix 解決了什么問(wèn)題

服務(wù)降級(jí),服務(wù)熔斷,服務(wù)限流,接近實(shí)時(shí)的監(jiān)控

服務(wù)熔斷

概念

服務(wù)熔斷 熔斷機(jī)制是應(yīng)對(duì)雪崩效應(yīng)的一種微服務(wù)鏈路保護(hù)機(jī)制。當(dāng)扇出鏈路的某個(gè)微服務(wù)不可用或者響應(yīng)時(shí)間太長(zhǎng)時(shí)，會(huì)進(jìn)行服務(wù)的降級(jí)，進(jìn)而熔斷該節(jié)點(diǎn)微服務(wù)的調(diào)用，快速返回"錯(cuò)誤"的響應(yīng)信息。當(dāng)檢測(cè)到該節(jié)點(diǎn)微服務(wù)調(diào)用響應(yīng)正常后恢復(fù)調(diào)用鏈路。在SpringCloud框架里熔斷機(jī)制通過(guò)Hystrix實(shí)現(xiàn)。Hystrix會(huì)監(jiān)控微服務(wù)間調(diào)用的狀況，當(dāng)失敗的調(diào)用到一定閾值，缺省是5秒內(nèi)20次調(diào)用失敗就會(huì)啟動(dòng)熔斷機(jī)制。熔斷機(jī)制的注解是@HystrixCommand。

新建microservicecloud-provider-dept-hystrix-8001

添加相關(guān)的pom依賴

????<dependencies>
????????<dependency>
????????????<groupId>com.yang</groupId>
????????????<artifactId>microservicecloud-api</artifactId>
????????????<version>1.0-SNAPSHOT</version>
????????</dependency>

????????<!--??hystrix?-->
????????<dependency>
????????????<groupId>org.springframework.cloud</groupId>
????????????<artifactId>spring-cloud-starter-hystrix</artifactId>
????????</dependency>

????????<!--?將微服務(wù)provider側(cè)注冊(cè)進(jìn)eureka?-->
????????<dependency>
????????????<groupId>org.springframework.cloud</groupId>
????????????<artifactId>spring-cloud-starter-eureka</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>org.springframework.cloud</groupId>
????????????<artifactId>spring-cloud-starter-config</artifactId>
????????</dependency>
????????<!--?actuator監(jiān)控信息完善?-->
????????<dependency>
????????????<groupId>org.springframework.boot</groupId>
????????????<artifactId>spring-boot-starter-actuator</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>junit</groupId>
????????????<artifactId>junit</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>mysql</groupId>
????????????<artifactId>mysql-connector-java</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>com.alibaba</groupId>
????????????<artifactId>druid</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>ch.qos.logback</groupId>
????????????<artifactId>logback-core</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>org.mybatis.spring.boot</groupId>
????????????<artifactId>mybatis-spring-boot-starter</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>org.springframework.boot</groupId>
????????????<artifactId>spring-boot-starter-jetty</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>
????????</dependency>
????????<!--?修改后立即生效，熱部署?-->
????????<dependency>
????????????<groupId>org.springframework</groupId>
????????????<artifactId>springloaded</artifactId>
????????</dependency>
????????<dependency>
????????????<groupId>org.springframework.boot</groupId>
????????????<artifactId>spring-boot-devtools</artifactId>
????????</dependency>
????</dependencies>

創(chuàng)建application.yml

server:
??port:?8001
??
mybatis:
??config-location:?classpath:mybatis/mybatis.cfg.xml????????#?mybatis配置文件所在路徑
??type-aliases-package:?com.yang.entity????#?所有Entity別名類(lèi)所在包
??mapper-locations:
??-?classpath:mybatis/mapper/**/*.xml???????????????????????#?mapper映射文件
????
spring:
???application:
????name:?microservicecloud-dept?
???datasource:
????type:?com.alibaba.druid.pool.DruidDataSource????????????#?當(dāng)前數(shù)據(jù)源操作類(lèi)型
????driver-class-name:?org.gjt.mm.mysql.Driver??????????????#?mysql驅(qū)動(dòng)包
????url:?jdbc:mysql://localhost:3306/cloudDB01??????????????#?數(shù)據(jù)庫(kù)名稱
????username:?root
????password:?root
????dbcp2:
??????min-idle:?5???????????????????????????????????????????#?數(shù)據(jù)庫(kù)連接池的最小維持連接數(shù)
??????initial-size:?5???????????????????????????????????????#?初始化連接數(shù)
??????max-total:?5??????????????????????????????????????????#?最大連接數(shù)
??????max-wait-millis:?200??????????????????????????????????#?等待連接獲取的最大超時(shí)時(shí)間

eureka:
??client:?#客戶端注冊(cè)進(jìn)eureka服務(wù)列表內(nèi)
????service-url:?
#??????defaultZone:?http://localhost:7001/eureka
???????defaultZone:?http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/
??instance:
????instance-id:?microservicecloud-dept8001-hystrix???#自定義服務(wù)名稱信息
????prefer-ip-address:?true?????#訪問(wèn)路徑可以顯示IP地址?????
?
info:?
??app.name:?atguigu-microservicecloud
??company.name:?www.atguigu.com
??build.artifactId:?$project.artifactId$
??build.version:?$project.version$

創(chuàng)建mybatis.cfg.xml配置文件

<?xml?version="1.0"?encoding="UTF-8"??>
<!DOCTYPE?configuration
??PUBLIC?"-//mybatis.org//DTD?Config?3.0//EN"
??"http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
<settings>
??<setting?name="cacheEnabled"?value="true"?/><!--?二級(jí)緩存開(kāi)啟?-->
?</settings>
</configuration>

創(chuàng)建mapper配置文件

<?xml?version="1.0"?encoding="UTF-8"??>
<!DOCTYPE?mapper?PUBLIC?"-//mybatis.org//DTD?Mapper?3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper?namespace="com.yang.dao.DeptDao">

?<select?id="findById"?resultType="com.yang.entity.Dept"?parameterType="Long">
??select?deptno,dname,db_source?from?dept?where?deptno=#{deptno};
?</select>
?<select?id="findAll"?resultType="com.yang.entity.Dept">
??select?deptno,dname,db_source?from?dept;
?</select>
?<insert?id="addDept"?parameterType="com.yang.entity.Dept">
??INSERT?INTO?dept(dname,db_source)?VALUES(#{dname},DATABASE());
?</insert>
</mapper>

創(chuàng)建控制類(lèi)controlelr

package?com.yang.controler;



import?com.yang.entity.Dept;
import?com.yang.service.DeptService;
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.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;

@RestController
public?class?DeptController
{
????@Autowired
????private?DeptService?service?=?null;

????@RequestMapping(value="/dept/get/{id}",method=RequestMethod.GET)
????@HystrixCommand(fallbackMethod?=?"processHystrix_Get")
????public?Dept?get(@PathVariable("id")?Long?id)
????{
????????Dept?dept?=??this.service.get(id);
????????if(null?==?dept)
????????{
????????????throw?new?RuntimeException("該ID："+id+"沒(méi)有沒(méi)有對(duì)應(yīng)的信息");
????????}
????????return?dept;
????}

????public?Dept?processHystrix_Get(@PathVariable("id")?Long?id)
????{
????????return?new?Dept().setDeptno(id)
????????????????.setDname("該ID："+id+"沒(méi)有沒(méi)有對(duì)應(yīng)的信息,null--@HystrixCommand")
????????????????.setDb_source("no?this?database?in?MySQL");
????}
}

創(chuàng)建dao層

package?com.yang.dao;

import?com.yang.entity.Dept;
import?org.apache.ibatis.annotations.Mapper;

import?java.util.List;

@Mapper
public?interface?DeptDao?{
????public?boolean?addDept(Dept?dept);

????public?Dept?findById(Long?id);

????public?List<Dept>?findAll();

}

創(chuàng)建service實(shí)現(xiàn)類(lèi)

package?com.yang.service.impl;


import?com.yang.dao.DeptDao;
import?com.yang.entity.Dept;
import?com.yang.service.DeptService;
import?org.springframework.beans.factory.annotation.Autowired;
import?org.springframework.stereotype.Service;

import?java.util.List;

@Service
public?class?DeptServiceImpl?implements?DeptService?{
????@Autowired
????private?DeptDao?dao?;

????@Override
????public?boolean?add(Dept?dept)
????{
????????return?dao.addDept(dept);
????}

????@Override
????public?Dept?get(Long?id)
????{
????????return?dao.findById(id);
????}

????@Override
????public?List<Dept>?list()
????{
????????return?dao.findAll();
????}

}

創(chuàng)建啟動(dòng)類(lèi)

package?com.yang;

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?//本服務(wù)啟動(dòng)后會(huì)自動(dòng)注冊(cè)進(jìn)eureka服務(wù)中
@EnableCircuitBreaker//對(duì)hystrixR熔斷機(jī)制的支持
public?class?DeptProvider8001_Hystrix_App
{
????public?static?void?main(String[]?args)
????{
????????SpringApplication.run(DeptProvider8001_Hystrix_App.class,?args);
????}
}

完

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