SpringCloud使用Eureka

基于springboot2.6.3，仅介绍单机版，分布式开发略有不同

大致步骤：

1. 新建module A，选择eureka作为注册中心，启动类上添加@EnableEurekaServer，添加pom依赖
2. 服务提供者module B（注册到注册中心的业务处理者）启动类添加@EnableEurekaClient与相关依赖
3. 消费者module C（发现服务并消费的服务）启动类添加@EnableFeignClients、@EnableDiscoveryClient与相关依赖
4. 消费者通过FeignClient进程服务间的调用

详细步骤：

1、新建 module A 作为注册中心的服务

​ 地址：localhost:8900

• 选择Eureka Server（不选择也行，手动在pom中添加依赖）

• 配置yml

  server:
  port: 8900
  eureka:
  instance:
  hostname: localhost
  client:
  #单机版不用把本身注册进去
  register-with-eureka: false
  fetch-registry: false
  service-url:
  defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

• 添加依赖

  <properties>
  <java.version>1.8</java.version>
  <spring-cloud.version>2021.0.0</spring-cloud.version>
  </properties>
  <dependencies>
  <dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
  </dependency>
  </dependencies>
  <dependencyManagement>
  <dependencies>
  <dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-dependencies</artifactId>
  <version>${spring-cloud.version}</version>
  <type>pom</type>
  <scope>import</scope>
  </dependency>
  </dependencies>
  </dependencyManagement>

• 启动类添加注解

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

2、处理服务提供者module B

​ 地址：localhost:8086

• yml配置

  server:
  port: 8086
  spring:
  datasource:
  #mysql
  driver-class-name: com.mysql.cj.jdbc.Driver
  url: jdbc:mysql://localhost:3306/shop?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2b8
  username: root
  password: root
  application:
  #定义应用程序的名称，注册中心使用
  name: producer
  eureka:
  client:
  service-url:
  #注册中心地址
  defaultZone: http://localhost:8900/eureka/

• 添加pom

  <dependencies>
  <!--  eureka客户端  -->
  <dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
  </dependency>
  <!-- 其他依赖 -->
  </dependencies>
  <dependencyManagement>
  <!-- 与注册中心版本保持一致 -->
  <dependencies>
  <dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-dependencies</artifactId>
  <version>2021.0.0</version>
  <type>pom</type>
  <scope>import</scope>
  </dependency>
  </dependencies>
  </dependencyManagement>

• 启动类添加依赖

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

• controller示例

  @RestController
  public class ProductController {
  @RequestMapping(value = "select", method = RequestMethod.GET)
  public String select(@RequestParam Long id) {
  return "id===="+id;
  }
  }

3、消费者module C

​ 服务地址：localhost:8088

• 配置yml

  spring:
  application:
  name: consumer
  server:
  port: 8088
  
  eureka:
  client:
  service-url:
  defaultZone: http://localhost:8900/eureka/

• 添加pom

  <dependencies>
  <!-- Eureka客户端依赖 -->
  <dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
  </dependency>
  <!-- 用来声明feign可以进行服务间调用 -->
  <dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-feign</artifactId>
  <version>1.4.7.RELEASE</version>
  </dependency>
  <!--其他依赖 -->
  </dependencies>
  
  <dependencyManagement>
  <dependencies>
  <dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-dependencies</artifactId>
  <version>2021.0.0</version>
  <type>pom</type>
  <scope>import</scope>
  </dependency>
  </dependencies>
  </dependencyManagement>

• 启动类：

  // 开启feign进行远程调用
  @EnableFeignClients
  // 开启发现其他服务
  @EnableDiscoveryClient
  @SpringBootApplication
  public class ConsumerApplication {
  public static void main(String[] args) {
  SpringApplication.run(ConsumerApplication.class, args);
  }
  }

• controller示例：

  现在需要通过consumer去调用producer的select方法，在consumer中先定义一个controller接收请求

  @RestController
  public class ConsumerController {
  @Autowired
  ProducerService producerService;
  
  @RequestMapping(value = "selectProducerById", method = RequestMethod.GET)
  public String selectProducerById(@RequestParam Long id) {
  return producerService.select(id);
  }
  }

• ProducerService接口

  上面producerService的定义

  /**
  value="需要远程调用的应用的名称"
  这里对应提供者module A的应用名称producer
  **/
  @FeignClient(value = "producer")
  public interface OrderService {
  //对应于ProducerController中的select方法
  @RequestMapping(value = "select", method = RequestMethod.GET)
  String select(@RequestParam Long id);
  
  }

通过调用消费者module C 的ConsumerController的selectProducerById方法

来请求提供者module A 的ProducerController中的select方法：

localost:8088/selectProducerById?id=1

返回结果: id====1