SpringCloud(Eureka的使用)

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7.2 EurekaServer服务端安装

1.创建名为cloud-eureka-server7001的Maven工程

2.修改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>cloud</artifactId>
        <groupId>com.caq.cloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

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

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <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.caq.cloud</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>

区别：

<!-- eureka新旧版本 -->
<!-- 以前的老版本（2018）-->
<dependency>
    <groupid>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>

<!-- 现在新版本（2020.2）--><!-- 我们使用最新的 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>

3.添加application.yml

server:
  port: 7001

eureka:
  instance:
    hostname: eureka7001.com #eureka服务端的实例名称
  client:
    register-with-eureka: false     #false表示不向注册中心注册自己。
    fetch-registry: 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
    service-url:
      #单机就是7001自己
      defaultZone: http://eureka7001.com:7001/eureka/

4.主启动

package com.caq.cloud;

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);
    }
}

==测试==

运行EurekaMain7001，浏览器输入http://localhost:7001/回车，会查看到Spring Eureka服务主页。

7.2.1 支付微服务8001入驻进EurekaServer

EurekaClient端cloud-provider-payment8001将注册进EurekaServer成为服务提供者provider

1.修改cloud-provider-payment8001

2.改POM

添加spring-cloud-starter-netflix-eureka-client依赖

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

3.写YML

在原有基础上添加

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

4.主启动

package com.caq.cloud;

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

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

==测试==

浏览器输入 - http://localhost:7001/ 主页内的Instances currently registered with Eureka会显示cloud-provider-payment8001的配置文件application.yml设置的应用名cloud-payment-service

自我保护机制

EMERGENCY! EUREKA MAY BE INCORRECTLY CLAIMING INSTANCES ARE UP WHEN THEY’RE NOT. RENEWALS ARELESSER THAN THRESHOLD AND HENCFT ARE NOT BEING EXPIRED JUST TO BE SAFE.

紧急情况！EUREKA可能错误地声称实例在没有启动的情况下启动了。续订小于阈值，因此实例不会为了安全而过期。

7.2.2 订单微服务80入驻进EurekaServer

EurekaClient端cloud-consumer-order80将注册进EurekaServer成为服务消费者consumer

1.修改cloud-consumer-order80模块

2.POM

在原有基础上添加

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

3.YML

server:
  port: 80

spring:
  application:
    name: cloud-order-service

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://eureka7001.com:7001/eureka, http://eureka7002.com:7002/eureka

4.主启动

package com.caq.cloud;

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

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

5.业务类

package com.caq.cloud.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class ApplicationContextConfig {
    //通过注解的方式注入，这样我们的容器里就有这个resttemplate对象
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
}

package com.caq.cloud.controller;

import com.caq.cloud.entities.CommonResult;
import com.caq.cloud.entities.Payment;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@RestController
@Slf4j
public class OrderController {

    //    public static final String PAYMENT_URL = "http://localhost:8001";
    public static final String PAYMENT_URL = "http://CLOUD-PAYMENT-SERVICE";

    @Resource
    private RestTemplate resetTemplate;

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

    @GetMapping("/consumer/payment/get/{id}")
    public CommonResult<Payment> getPayment(@PathVariable("id") Long id){
        return resetTemplate.getForObject(PAYMENT_URL+"/payment/get/"+id,CommonResult.class);
    }
}

==测试==

启动cloud-provider-payment8001、cloud-eureka-server7001和cloud-consumer-order80这三工程。 浏览器输入 http://localhost:7001 , 在主页的Instances currently registered with Eureka将会看到cloud-provider-payment8001、cloud-consumer-order80两个工程名。

访问测试