Spring Cloud服务注册中心及发现与消费

使用Spring Cloud中的Eureka创建微服务注册中心，然后服务提供者向其中注册服务，服务消费者调用已注册的服务。即：服务注册中心（Eureka）、服务提供者（Provider）、服务消费者（Consumer）。

1、服务注册中心（Eureka）

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>

	<groupId>com.micloud</groupId>
	<artifactId>miservices</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>miservices</name>
	<description>miservices project for Spring Cloud</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.6.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Finchley.SR1</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>
</project>

application.properties
在默认设置下，服务注册中心也会将"自己"作为客户端来尝试注册它本身，禁用它的客户端注册行为。

spring.application.name=spring-cloud-eureka
server.port=9000
#是否将自己注册到Eureka Server，默认为true
eureka.client.register-with-eureka=false
#是否从Eureka Server获取注册信息，默认为true
eureka.client.fetch-registry=false
#设置与Eureka Server交互的地址，用于查询服务和注册服务
eureka.client.serviceUrl.defaultZone=http://localhost:${server.port}/eureka/

CloudApplication.java

@SpringBootApplication
@EnableEurekaServer//启动服务注册中心
public class CloudApplication {
	public static void main(String[] args) {
		SpringApplication.run(CloudApplication.class, args);
	}
}

启动Eureka测试上述代码，运行结果如下

2、服务提供者（Provider）

pom.xml spring boot版本与注册中心保持一致。在尝试使用与注册版本不一致的情况，尚未测试通过！

....
<groupId>com.micloud</groupId>
<artifactId>cloud_provider</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>cloud_provider</name>
<description>Demo project for Spring cloud_provider</description>
....
<dependencies>
	<dependency>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-starter</artifactId>
	</dependency>
	<dependency>
		<!-- 引入web模块 -->
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	<dependency>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
	</dependency>
</dependencies>
....

application.properties

spring.application.name=spring-cloud-provider
server.port=8081
eureka.client.serviceUrl.defaultZone=http://localhost:9000/eureka/

CloudProviderApplication.java

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

HelloController.java 模拟业务代码

@RestController
public class HelloController {    
    @RequestMapping("/hello")
    public Object hello(@RequestParam String name) {
    	Map<String,String> obj = new HashMap<String,String>();
    	obj.put("name", name);
    	obj.put("memo", "the messge come from Spring-Cloud-Provider");
        return obj;
    }
}

测试 单独启动、测试provider服务

3、服务消费者（Consumer）

pom.xml spring boot版本与注册中心保持一致。在尝试使用与注册版本不一致的情况，尚未测试通过！

....
<groupId>com.micloud</groupId>
<artifactId>cloud_consumer</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>cloud_consumer</name>
<description>Demo project for Spring Boot Consumer</description>
....
<dependencies>
	<dependency>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
	</dependency>	
</dependencies>
....

application.properties

spring.application.name=spring-cloud-consumer
server.port=8082
eureka.client.serviceUrl.defaultZone=http://localhost:9000/eureka/
# 服务提供者
provider.app.name=SPRING-CLOUD-PROVIDER

CloudConsumerApplication.java

@SpringBootApplication
@EnableDiscoveryClient
public class CloudConsumerApplication 
{
	@Bean//注册bean，也可以配置在config类中：@Configuration
	@LoadBalanced//坑，不仅仅是负载均衡，还可以使用服务名称调用服务，否则报错找不到主机
	public RestTemplate restTemplate() {
		return new RestTemplate();
    }

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

ConsumerController.java 模拟调用已注册的SPRING-CLOUD-PROVIDER服务

@RestController
public class ConsumerController {
	@Autowired
	private RestTemplate restTemplate;

	@Value("${provider.app.name}")//从配置文件获取数据
	private String serviceName;

	@RequestMapping(value = "/testhello")
	public String testProviderHello() {
		String result = restTemplate.getForObject("http://" + serviceName
				+ "/hello?name=tom", String.class);
		return "this is requestResult:" + result;
	}
}

4、启动、测试

启动 依次启动服务，Eureka运行结果，变化如下

测试 消费者调用服务，返回结果正确