EureKa服务注册发现与调用

公司需要对提高项目的响应速度，经研究决定使用eureka微服务改造项目，于是自己做了一个小demo进行学习。

一、eureka简介

Eureka是Netflix开发的服务发现框架，本身是一个基于REST的服务，主要用于定位运行在AWS域中的中间层服务，以达到负载均衡和中间层服务故障转移的目的。SpringCloud将它集成在其子项目spring-cloud-netflix中，以实现SpringCloud的服务发现功能。Eureka采用cs架构：Eureka Server和Eureka Client，即服务端和客户端。

客户端将服务注册到服务端，客户端之间可以通过eureka服务的注册信息进行调用。客户端可以同时注册多个eureka服务，从而实现高可用，客户端可以发布多个到eureka上实现负载均衡。

二、Eureka Serve服务端

1、首先构建一个springboot项目,并在pom.xml中添加依赖

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">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.1.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>cn.itcast</groupId>
	<artifactId>eureka</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>eureka</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
		<spring-cloud.version>Greenwich.RC2</spring-cloud.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</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>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

	<repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
		</repository>
	</repositories>
</project>

2、配置application.yml

server:
  port: 8761     
eureka:
  client:
    #是否向服务注册中心注册自己
    register-with-eureka: false
    #是否启用获取服务注册信息,不需要同步其他的Eureka Server节点的数据，故而设为false
    fetch-registry: false

3、主函数类中添加注解EurekaApplication

@EnableEurekaServer 
@SpringBootApplication
public class EurekaApplication {

	public static void main(String[] args) {
		SpringApplication.run(EurekaApplication.class, args);
	}

}

4、启动主函数就可以访问eureka注册中心了http://localhost:8761/

三、Eureka Client客户端

首先创建一个生产者，即服务的提供者，生产者和消费者没有绝对的区分，只是在服务调用的时候扮演的不同角色。

1、首先构建一个springboot项目,并在pom.xml中添加依赖

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">  
	<modelVersion>4.0.0</modelVersion>
  <parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.1.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
  <groupId>cn.vtits</groupId>
  <artifactId>provider</artifactId>
  <version>1.0.0-SNAPSHOT</version>
	<properties>
		<java.version>1.8</java.version>
		<spring-cloud.version>Greenwich.RC2</spring-cloud.version>
	</properties>
	<dependencies>
		<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency> 
			<groupId>org.springframework.boot</groupId> 
			<artifactId>spring-boot-starter</artifactId> 
		</dependency> 
		<dependency> 
		     <groupId>org.springframework.boot</groupId> 
			<artifactId>spring-boot-starter-web</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>
   <build>
   		<defaultGoal>compile</defaultGoal>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
  </build>
  <repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
		</repository>
	</repositories>
</project>

2、配置application.yml

server:
  port: 8762
spring:
  application:
    name: hello-service

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka #注册eureka的地址，由于eureka在本地

3、主函数添加注解

@Configuration
@EnableAutoConfiguration
@ComponentScan
public class ProviderApplication {
      public static void main(String[] args) {
          SpringApplication.run(ProviderApplication.class, args);
      }
}

4、添加测试用例

@RestController
public class MainController {

	@GetMapping("/test/{name}")
      String home(@PathVariable("name") String t) {
        return "Hello World!"+t;
      }
}

5、启动主函数打开eureka注册中心

看到我们的服务注册到eureka服务上了。

访问http://localhost:8762/test/JAVA

创建一个服务消费者

6、构建一个springboot项目,并在pom.xml中添加依赖

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">  
	<modelVersion>4.0.0</modelVersion>
  <parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.1.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
  <groupId>cn.vtits</groupId>
  <artifactId>provider</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  
	<properties>
		<java.version>1.8</java.version>
		<spring-cloud.version>Greenwich.RC2</spring-cloud.version>
	</properties>
	
	<dependencies>
	<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency> 
			<groupId>org.springframework.boot</groupId> 
			<artifactId>spring-boot-starter</artifactId> 
		</dependency> 
		<dependency> 
		     <groupId>org.springframework.boot</groupId> 
			<artifactId>spring-boot-starter-web</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>

   <build>
   		<defaultGoal>compile</defaultGoal>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
  </build>
  <repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
		</repository>
	</repositories>
</project>

7、主函数添加注解

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

8、配置application.yml

server:
  port: 8763
spring:
  application:
    name: consumer

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka

9、创建ServiceFeignClient类，作为服务调用接口

//name为生产者提供的服务名称
@FeignClient(name = "hello-service" )
public interface ServiceFeignClient {
	 
    //这里接口要与被生产者home一致
    @GetMapping("/test/{name}")
    String home(@PathVariable("name") String name);
}

10、编写ConsumerController，调用ServiceFeignClient

@RestController
public class ConsumerController {
	@Autowired
	ServiceFeignClient serviceFeignClient;

    @GetMapping("/test1/{name}")
    public String index(@PathVariable("name") String name) {
        return serviceFeignClient.home(name);
    }
}

11、启动主函数打开eureka注册中心

12、访问http://localhost:8763/test1/JDK

这样消费者就从eureka服务调用到了eureka生产者的服务。

EureKa服务注册发现与调用

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