SpringCloud之Eureka

shaoshaossm

发布于 2022-12-27 13:35:17

2410

发布于 2022-12-27 13:35:17

文章被收录于专栏：Java啊

基本知识

服务治理

Spring Cloud 封装了 Netflix 公司开发的 Eureka 模块来实现服务治理。

在传统的rpc远程调用框架中，管理每个服务与服务之间依赖关系比较复杂，管理比较复杂，所以需要使用服务治理，管理服务于服务之间依赖关系，可以实现服务调用、负载均衡、容错等，实现服务发现与注册。

服务注册

Eureka采用了CS的设计架构，Eureka Server 作为服务注册功能的服务器，它是服务注册中心。而系统中的其他微服务，使用 Eureka的客户端连接到 Eureka Server并维持心跳连接。这样系统的维护人员就可以通过 Eureka Server 来监控系统中各个微服务是否正常运行。

在服务注册与发现中，有一个注册中心。当服务器启动的时候，会把当前自己服务器的信息比如服务地址通讯地址等以别名方式注册到注册中心上。另一方（消费者|服务提供者），以该别名的方式去注册中心上获取到实际的服务通讯地址，然后再实现本地RPC调用RPC远程调用框架核心设计思想：在于注册中心，因为使用注册中心管理每个服务与服务之间的一个依赖关系(服务治理概念)。在任何rpc远程框架中，都会有一个注册中心(存放服务地址相关信息(接口地址))

Eureka包含两个组件

Eureka Server和Eureka Client

Eureka Server提供服务注册服务

各个微服务节点通过配置启动后，会在EurekaServer中进行注册，这样EurekaServer中的服务注册表中将会存储所有可用服务节点的信息，服务节点的信息可以在界面中直观看到。

EurekaClient通过注册中心进行访问

是一个Java客户端，用于简化Eureka Server的交互，客户端同时也具备一个内置的、使用轮询(round-robin)负载算法的负载均衡器。在应用启动后，将会向Eureka Server发送心跳(默认周期为30秒)。如果Eureka Server在多个心跳周期内没有接收到某个节点的心跳，EurekaServer将会从服务注册表中把这个服务节点移除（默认90秒）

服务提供者

8001目录结构

代码编写

PaymentController

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

    @Value("${server.port}")
    private String serverPort;
    @PostMapping(value = "/payment/create")
    public CommonResult create(@RequestBody Payment payment){
        int result = paymentService.create(payment);
        log.info("插入结果: "+result);
        if (result > 0){
            return new CommonResult(200,"插入数据操作成功"+serverPort,result);
        } else {
            return new CommonResult(444,"插入数据操作失败",null);
        }
    }

    @GetMapping(value = "/payment/get/{id}")
    public CommonResult getPaymentById(@PathVariable("id") Long id){
        Payment payment = paymentService.getPaymentById(id);
        log.info("获取结果: "+payment);
        if (payment != null){
            return new CommonResult(200,"查询成功"+serverPort,payment);
        } else {
            return new CommonResult(444,"查询失败，查询ID:",id);
        }
    }

}

PaymentDao

@Mapper
public interface PaymentDao {
    public int create(Payment payment);
    public Payment getPaymentById(@Param("id") Long id);
}

PaymentServiceImpl

@Service
public class PaymentServiceImpl implements PaymentService {
    @Resource
    private PaymentDao paymentDao;

    @Override
    public int create(Payment payment) {
        return paymentDao.create(payment);
    }

    @Override
    public Payment getPaymentById(Long id) {
        return paymentDao.getPaymentById(id);
    }
}

PaymentService

public interface PaymentService {
    public int create(Payment payment);
    public Payment getPaymentById(@Param("id") Long id);
}

PaymentMain8001

@SpringBootApplication
@EnableEurekaClient
public class PaymentMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain8001.class,args);
    }
}

PaymentDao.xml

<?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.ssm.springcloud.dao.PaymentDao">

    <resultMap id="BaseResultMap" type="com.ssm.springcloud.entities.Payment">
        <id column="id" property="id" jdbcType="BIGINT"/>
        <result column="serial" property="serial" jdbcType="VARCHAR"/>
    </resultMap>

    <insert id="create" parameterType="Payment" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO payment(SERIAL) VALUES(#{serial});
    </insert>

    <select id="getPaymentById" parameterType="Long" resultMap="BaseResultMap" >
        SELECT * FROM payment WHERE id=#{id};
    </select>

</mapper>

application.yml

server:
  port: 8001

spring:
  application:
    name: cloud-payment-service

  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springcloud?useSSL=false&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true
    username: root
    password: 密码
mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.ssm.springcloud.entities

pom.xml

<?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>springcloud2022</artifactId>
        <groupId>com.ssm.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-consumer-order80</artifactId>

    <dependencies>
        <!--eureka-server-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
            <groupId>com.ssm.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <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>
            <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>

服务消费者

80目录结构

代码编写

ApplicationContextConfig

@Configuration
public class ApplicationContextConfig {
    @Bean
    @LoadBalanced
    public RestTemplate getResTemplate() {
        return new RestTemplate();
    }

}

OrderController

@RestController
@Slf4j
public class OrderController {
//    public static final String PAYMENT_URL = "http://localhost:8001";
    public static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE"; //服务名称
    @Resource
    private RestTemplate restTemplate;

    @GetMapping("/consumer/payment/create")
    public ResponseEntity<CommonResult> create(Payment payment) {
        return restTemplate.postForEntity(PAYMENT_URL + "/payment/create", payment, CommonResult.class);
    }

    @GetMapping(value = "/consumer/payment/get/{id}",produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    public CommonResult getPayment(@PathVariable("id") Long id) {
        return restTemplate.getForObject(PAYMENT_URL+"/payment/get/"+id,CommonResult.class);
    }


}

OrderMain80

@SpringBootApplication
@EnableEurekaClient
public class OrderMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderMain80.class,args);
    }
}

公共模块 cloud-api-commons

将实体类的公共模块提取出来
在服务提供者和消费者模块中引入依赖

<dependency><!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
    <groupId>com.ssm.springcloud</groupId>
    <artifactId>cloud-api-commons</artifactId>
    <version>${project.version}</version>
</dependency>

Eureka项目基本构建

建立 7001module

pom.xml

<?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>springloud2022</artifactId>
        <groupId>com.ssm.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-eureka-server7001</artifactId>

    <dependencies>
        <!--eureka-server-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <!-- 引入自己定义的api通用包，可以使用Payment支付Entity -->
        <dependency>
            <groupId>com.ssm.springcloud</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <!--boot web actuator-->
        <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>
        <!--一般通用配置-->
        <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>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        </dependency>
    </dependencies>

</project>

application.yml

server:
  port: 7001

eureka:
  instance:
    hostname: localhost #eureka服务端的实例名称
  client:
    #false表示不向注册中心注册自己。
    register-with-eureka: false
    #false表示自己端就是注册中心，我的职责就是维护服务实例，并不需要去检索服务
    fetch-registry: false
    service-url:
      #设置与Eureka Server交互的地址查询服务和注册服务都需要依赖这个地址。
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

EurekaMain7001

package com.ssm.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
@EnableEurekaServer
public class EurekaMain7001 {
    public static void main(String[] args) {
        SpringApplication.run(EurekaMain7001.class,args);
    }
}

EurekaSever-provider

将注册EurekaSever成为服务提供者provider

pom.xml

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

application.yml

eureka:
  client:
    #表示是否将自己注册进EurekaServer默认为true。
    register-with-eureka: true
    #是否从EurekaServer抓取已有的注册信息，默认为true。单节点无所谓，集群必须设置为true才能配合ribbon使用负载均衡
    fetchRegistry: true
    service-url:
      defaultZone: http://localhost:7001/eureka

PaymentMain8001启动类

@SpringBootApplication
@EnableEurekaClient
public class PaymentMain8001
{
    public static void main(String[] args)
    {
        SpringApplication.run(PaymentMain8001.class,args);
    }
}

Eureka集群构建

微服务RPC远程服务调用最核心的是高可用，所以搭建Eureka注册中心集群，实现负载均衡+故障容错，相互注册，相互守望。

两个集群互相注册

再新建一个 7002Module
找到 C:\Windows\System32\drivers\etc 修改映射配置文件添加进host文件

127.0.0.1 eureka7001.com
127.0.0.1 eureka7002.com

application.yml

server:
  port: 7001

eureka:
  instance:
    hostname: eureka7001.com 
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://eureka7002.com:7002/eureka/

server:
  port: 7002

eureka:
  instance:
    hostname: eureka7002.com
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/

将其他模块注册进7001和7002Eureka集群

eureka:
  client:
    register-with-eureka: true
    fetchRegistry: true
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka  # 集群版

创建两个服务提供者8001&8002

和创建8001一样，修改端口号即可

修改8001和8002controller 加入

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

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

    @Value("${server.port}")
    private String serverPort;
    @PostMapping(value = "/payment/create")
    public CommonResult create(@RequestBody Payment payment){
        int result = paymentService.create(payment);
        log.info("插入结果: "+result);
        if (result > 0){
            return new CommonResult(200,"插入数据操作成功"+serverPort,result);
        } else {
            return new CommonResult(444,"插入数据操作失败",null);
        }
    }

    @GetMapping(value = "/payment/get/{id}")
    public CommonResult getPaymentById(@PathVariable("id") Long id){
        Payment payment = paymentService.getPaymentById(id);
        log.info("获取结果: "+payment);
        if (payment != null){
            return new CommonResult(200,"查询成功"+serverPort,payment);
        } else {
            return new CommonResult(444,"查询失败，查询ID:",id);
        }
    }

}

使用@LoadBalanced注解赋予RestTemplate负载均衡的能力

@Configuration
public class ApplicationContextConfig {
    @Bean
    @LoadBalanced
    public RestTemplate getResTemplate() {
        return new RestTemplate();
    }

}

修改PAYMENT_URL为服务名称

@RestController
@Slf4j
public class OrderController {
//    public static final String PAYMENT_URL = "http://localhost:8001";
    public static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE"; //服务名称
    @Resource
    private RestTemplate restTemplate;

    @GetMapping("/consumer/payment/create")
    public ResponseEntity<CommonResult> create(Payment payment) {
        return restTemplate.postForEntity(PAYMENT_URL + "/payment/create", payment, CommonResult.class);
    }

    @GetMapping(value = "/consumer/payment/get/{id}",produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
    public CommonResult getPayment(@PathVariable("id") Long id) {
        return restTemplate.getForObject(PAYMENT_URL+"/payment/get/"+id,CommonResult.class);
    }


}

最终结果

actuator信息完善

修改服务名和增加访问信息显示ip地址

eureka:
  client:
    #表示是否将自己注册进EurekaServer默认为true。
    register-with-eureka: true
    #是否从EurekaServer抓取已有的注册信息，默认为true。单节点无所谓，集群必须设置为true才能配合ribbon使用负载均衡
    fetchRegistry: true
    service-url:
      #defaultZone: http://localhost:7001/eureka
      defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka  # 集群版
  instance:
    instance-id: payment8002 # 增加服务别名
    prefer-ip-address: true # 访问路径显示IP地址

服务发现Discovery

编写controller类

@GetMapping(value = "/payment/discovery")
   public Object discovery(){
       List<String> services = discoveryClient.getServices();
       for (String element:services
            ) {
           log.info("element"+element);
       }
       List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");
       for (ServiceInstance instance:instances
            ) {
       log.info(instance.getServiceId()+"\t"+instance.getHost()+"\t"+instance.getPort()+"\t"+instance.getUri());
       }
       return this.discoveryClient;
   }

增加启动注解

@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
public class PaymentMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain8001.class,args);
    }
}

Eureka自我保护

自我保护机制默认是开启的
保护模式主要用于一组客户端和Eureka Server之间存在网络分区场景下的保护。一旦进入保护模式， Eureka Server将会尝试保护其服务注册表中的信息，不再删除服务注册表中的数据，也就是不会注销任何微服务。

关闭自我保护机制

7001

eureka:
  instance:
    hostname: eureka7001.com #eureka服务端的实例名称
  client:
    #false表示不向注册中心注册自己。
    register-with-eureka: false
    #false表示自己端就是注册中心，我的职责就是维护服务实例，并不需要去检索服务
    fetch-registry: false
    service-url:
      #设置与Eureka Server交互的地址查询服务和注册服务都需要依赖这个地址。
#      defaultZone: http://eureka7002.com:7002/eureka/
      # 单机指向自己
      defaultZone: http://eureka7001.com:7001/eureka/
  server:
    #关闭自我保护机制，保证不可用服务被及时踢除
    enable-self-preservation: false
    eviction-interval-timer-in-ms: 2000 # 默认90s 改成2s

8001生产者EurekaClient客户端

server:
  port: 8001

spring:
  application:
    name: cloud-payment-service

  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springcloud?useSSL=false&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true
    username: root
    password: 密码
mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.ssm.springcloud.entities

eureka:
  client:
    #表示是否将自己注册进EurekaServer默认为true。
    register-with-eureka: true
    #是否从EurekaServer抓取已有的注册信息，默认为true。单节点无所谓，集群必须设置为true才能配合ribbon使用负载均衡
    fetchRegistry: true
    service-url:
      # 单机版
      defaultZone: http://localhost:7001/eureka
#      defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka  # 集群版

  instance:
      instance-id: payment8001
      prefer-ip-address: true
      #Eureka客户端向服务端发送心跳的时间间隔，单位为秒(默认是30秒)
      lease-renewal-interval-in-seconds: 1
      #Eureka服务端在收到最后一次心跳后等待时间上限，单位为秒(默认是90秒)，超时将剔除服务
      lease-expiration-duration-in-seconds: 2

测试

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原始发表：2022-03-14，如有侵权请联系 cloudcommunity@tencent.com 删除

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