Spring Clooud 入门

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发布日期:   2018-08-07

Spring Cloud 入门

一、spring cloud简介

spring cloud 为开发人员提供了快速构建分布式系统的一些工具，包括配置管理、服务发现、断路器、路由、微代理、事件总线、全局锁、决策竞选、分布式会话等等。它运行环境简单，可以在开发人员的电脑上跑。

二、创建服务注册中心
在这里，我们需要用的的组件上Spring Cloud Netflix的Eureka ,eureka是一个服务注册和发现模块。

2.1 首先创建一个maven主工程。

2.2 然后创建2个model工程:一个model工程作为服务注册中心，即Eureka Server,另一个作为Eureka Client。

下面以创建server为例子，详细说明创建过程：

右键工程->创建model-> 选择spring initialir 如下图：

下一步->选择cloud discovery->eureka server ,然后一直下一步就行了。

pom文件如下

<?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.coderpwh</groupId>
	<artifactId>eureka-server</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>eureka-server</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>com.coderpwh</groupId>
		<artifactId>sc-f-chapter2</artifactId>
		<version>1.0-SNAPSHOT</version>
	</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>

2.3 启动一个服务注册中心，只需要一个注解@EnableEurekaServer，这个注解需要在springboot工程的启动application类上加：

package com.coderpwh;

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

@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {

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

**2.4 **eureka是一个高可用的组件，它没有后端缓存，每一个实例注册之后需要向注册中心发送心跳（因此可以在内存中完成），在默认情况下erureka server也是一个eureka client ,必须要指定一个 server。eureka server的配置文件appication.yml：

server:
  port: 8761

eureka:
  instance:
    hostname: localhost
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

spring:
  application:
    name: eurka-server

2.5 eureka server 是有界面的，启动工程,打开浏览器访问：
http://localhost:8761 ,界面如下：

三、创建一个服务提供者 (eureka client)

当client向server注册时，它会提供一些元数据，例如主机和端口，URL，主页等。Eureka server 从每个client实例接收心跳消息。 如果心跳超时，则通常将该实例从注册server中删除。

创建过程如上。pom文件如下

<?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.coderpwh</groupId>
	<artifactId>service-hi</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>service-hi</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>com.coderpwh</groupId>
		<artifactId>sc-f-chapter2</artifactId>
		<version>1.0-SNAPSHOT</version>
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.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-web</artifactId>
		</dependency>
	</dependencies>

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

</project>

通过注解@EnableEurekaClient 表明自己是一个eurekaclient.

package com.coderpwh;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
@RestController
public class ServiceHiApplication {

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


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

	@RequestMapping("/hi")
	public String home(@RequestParam(value = "name", defaultValue = "forezp") String name) {
		return "hi " + name + " ,i am from port:" + port;
	}

}

仅仅@EnableEurekaClient是不够的，还需要在配置文件中注明自己的服务注册中心的地址，application.yml配置文件如下：

server:
  port: 8763

spring:
  application:
    name: service-hi

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

需要指明spring.application.name,这个很重要，这在以后的服务与服务之间相互调用一般都是根据这个name 。
启动工程，打开http://localhost:8761 ，即eureka server 的网址：

四 : ribbon简介

Ribbon is a client side load balancer which gives you a lot of control over the behaviour of HTTP and TCP clients. Feign already uses Ribbon, so if you are using @FeignClient then this section also applies.

—–摘自官网

ribbon是一个负载均衡客户端，可以很好的控制htt和tcp的一些行为。Feign默认集成了ribbon。

ribbon 已经默认实现了这些配置bean：

IClientConfig ribbonClientConfig: DefaultClientConfigImpl

IRule ribbonRule: ZoneAvoidanceRule

IPing ribbonPing: NoOpPing

ServerList ribbonServerList: ConfigurationBasedServerList

ServerListFilter ribbonServerListFilter: ZonePreferenceServerListFilter

ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer

在上面的基础上，我们接着来创建 ribbon工程

重新新建一个spring-boot工程，取名为：service-ribbon;

pom 文件如下

<?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.coderpwh</groupId>
	<artifactId>service-ribbon</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>service-ribbon</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>com.coderpwh</groupId>
		<artifactId>sc-f-chapter2</artifactId>
		<version>1.0-SNAPSHOT</version>
	</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-client</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
		</dependency>
	</dependencies>

</project>

新建之后的项目

application.yml的配置

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 8764
spring:
  application:
    name: service-ribbon

在工程的启动类中,通过@EnableDiscoveryClient向服务中心注册；并且向程序的ioc注入一个bean: restTemplate;并通过@LoadBalanced注解表明这个restRemplate开启负载均衡的功能

package com.coderpwh;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
public class ServiceRibbonApplication {

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

	@Bean
	@LoadBalanced
	RestTemplate restTemplate() {
		return new RestTemplate();
	}
}

service 层

package com.coderpwh.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

/**
 * Created by 彭文浩 on 2018/8/6.
 */
@Service
public class HelloService {
    @Autowired
    RestTemplate restTemplate;

    public String hiService(String name) {
        return restTemplate.getForObject("http://SERVICE-HI/hi?name="+name,String.class);
    }
}

控制层


package com.coderpwh.web;

import com.coderpwh.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

/**
 * Created by 彭文浩 on 2018/8/6.
 */
@RestController
public class HelloControler {
    @Autowired
    HelloService helloService;

    @GetMapping(value = "/hi")
    public String hi(@RequestParam String name) {
        return helloService.hiService( name );
    }
}

效果如图:

四:此时的架构图:

  • 一个服务注册中心，eureka server,端口为8761
  • service-hi 工程run了2会，各自端口为8762,8763 分别向注册中心注册
  • service-ribbon 端口为8764，向服务注册中心注册
  • 当service-ribbon 通过restTemplate调用 service-hi的hi接口，因为ribbon进行了负载均衡，会轮流的调用service-hi：8762和8763两个端口的hi接口

源码下载：https://github.com/coder-PengWenHao/Spring-Boot-Cloud-demos

文章作者: coderpwh
文章链接: https://coderpwh.net/2018/08/07/springcloud/
版权声明: 本博客所有文章除特別声明外，均采用 CC BY 4.0 许可协议。转载请注明来源 coderpwh !
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