Spring Cloud简述及简单入门实例

 

1 Spring Cloud简述及简单入门实例

1.1 概述

Spring Cloud基于Spring Boot，提供了多个组件来帮助企业进行微服务系统建设；它提供的主要功能有：服务注册中心/服务注册/服务调用/负载均衡/断路器等；一般情况下它都是使用已有的开源软件，在其基础上按Spring Boot的理念来进行封装，简化各种个组件的调用以及各个组件之间的交互。

1.2 常用组件

Spring Cloud主要包含以下常用组件：Eureka或nacos、Ribbon、Feign

1.2.1 Eureka

分成两类：

（1）一是注册中心及EurekaServer，用于提供服务注册/服务申请等功能；

（2）一是被注册者及服务提供者EurekaClient，用于向EurekaServer注册服务并可从EurekaServer获取需要调用的服务地址信息；

需要向外提供服务的应用，需要使用EurekaClient来向Server注册服务。

1.2.2 Ribbon

负责进行客户端负载均衡的组件；一般与RestTemplate结合，在访问EurekaClient提供的服务时进行负载均衡处理。

也就是说，Ribbon用于服务调用者向被调用者进行服务调用，并且如果服务者有多个节点时，会进行客户端的负载均衡处理；

1.2.3 Feign

与Ribbon功能类型，用于调用方与被调用方的服务调用，同时进行客户端负载均衡的处理；不过它能提供类似本地调用的方式调用远程的EurekaClient提供的服务；它实际上是在Ribbon基础上进行了进一步的封装来提高调用服务的简便性。

1.3 使用示例

假设现在有springcloud-eurekaClient和springcloud-eurekaClient2向外提供服务，该服务同时部署两个节点；Client通过Feign或者是Ribbon调用其提供的服务，其部署关系及数据流向图如下所示：

 

第一步：启动注册中心（启动springCloud-EurekaServer项目）；服务提供者及调用者向服务中心注册；

第二步：服务调用者向服务中心申请服务，根据服务中心返回的地址信息调用服务提供者提供的服务；

第三步：注册中心通过心跳检测方式检测服务提供者的状态，当某个提供者连接不上时，发送消息通知所有注册者；

下面详细说明每个节点的实现； 具体代码见

1.4 Eureka服务端（springCloud-EurekaServer）

新建springCloud-EurekaServer   Maven工程，具体目录结构如下图

 

1.4.1 pom.xml配置

<?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>org.example</groupId>
    <artifactId>springCloud</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.4.RELEASE</version>
        <relativePath />
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- eureka -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka-server</artifactId>
        </dependency>
    </dependencies>

    <!-- Spring Cloud -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR4</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>



</project>

 

1.4.2 Application.yml配置

server:
  port: 8888

#应用的名字
spring:
  application:
    name: springCloud-EurekaServer
eureka:
  instance:
    hostname: localhost
  client:
    registerWithEureka: false  # 由于该应用为注册中心，所以设置为false，代表不向注册中心注册自己
    fetchRegistry: false  # 由于注册中心的职责就是维护服务实例，他并不需要去检索服务，所以也设置为false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

1.4.3 Application.cs文件

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

// 通过@EnableEurekaServer注解启动一个服务注册中心提供给其他应用进行对话。
@EnableEurekaServer
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class,args);
        System.out.println("启动成功！");
    }
}

1.4.4 启动结果

启动完后通过http://localhost:8888/可以看到EurekaServer的监控页面； 此时还没有节点注册，如下图；

 

1.5 Eureka服务提供方（springcloud-eurekaClient）

新建springcloud-eurekaClient   Maven工程，具体目录结构如下图

1.5.1 pom.xml配置

<?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>org.example</groupId>
    <artifactId>springcloud-eurekaserver</artifactId>
    <version>1.0-SNAPSHOT</version>

    <!-- Spring Boot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.4.RELEASE</version>
        <relativePath />
    </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.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <!-- Spring Cloud -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR4</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

1.5.2 Application.yml配置

server:
  port: 8901
  
#应用的名字
spring:
  application:
    name: springcloud-eurekaClient
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8888/eureka/

1.5.3 Application.cs文件

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

@EnableEurekaClient
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
        System.out.println("启用成功！");
    }
}

1.5.4 ComputeController.cs文件

package com.lijun.controller;

import org.apache.log4j.Logger;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class ComputeController {
   private final Logger logger = Logger.getLogger(getClass());

    @RequestMapping(value = "/add" ,method = RequestMethod.GET)
    public Integer add(@RequestParam Integer a, @RequestParam Integer b) {
       
        Integer r = a + b;
        logger.info("/add, result:" + r);
        return r;
    }
    
   @GetMapping("/hello")
    public String sayHi(@RequestParam String name){
       return " Welcome-: "+name;
    }
}

1.5.5 启动结果

启动main函数后，通过http://localhost:8888可以看到已经有节点注册；

如果要启动多个节点做负载均衡，可以修改application.yml中的端口信息后再次启动main函数就可以了。

 

1.6 调用方（springCloud-feignClient）

新建springCloud-feignClient   Maven工程，具体目录结构如下图

1.6.1 pom.xml配置

<?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>org.example</groupId>
    <artifactId>springCloud-feignClient</artifactId>
    <version>1.0-SNAPSHOT</version>

    <!-- Spring Boot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.4.RELEASE</version>
        <relativePath />
    </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.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-feign</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <!-- Spring Cloud -->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR4</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>


</project>

1.6.2 Application.yml配置

server:
  port: 8999
  
#应用的名字
spring:
  application:
    name: springCloud-feignClient
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8888/eureka/

1.6.3 FeignApplication.cs文件

package com.lijun.feign;

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

/**
 * 在启动类上加@EnableFeignClients注解，
 * 如果你的Feign接口定义跟你的启动类不在一个包名下，还需要制定扫描的包
 * 名@EnableFeignClients(basePackages = "com.lijun.api.client")
 * @author ljl
 *
 */
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class FeignApplication {

    public static void main(String[] args) {

        SpringApplication.run(FeignApplication.class, args);
        System.out.println("启动成功");
    }
}

1.6.4 FeignConfiguration.cs文件

package com.lijun.feign.config;

import feign.Retryer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.concurrent.TimeUnit;

/**
 * 自定义配置类
 * @author ljl
 *
 */
@Configuration
public class FeignConfiguration {
   
   /**
    * 覆盖默认的Retryer的Bean，重试间隔为100毫秒，最大重试时间为1秒，重试次数5次
    * @return
    */
   @Bean
   public Retryer feignRetryer(){
      return new Retryer.Default(100, TimeUnit.SECONDS.toMillis(1), 5);
   }

}

1.6.5 EurekaClientFeign.cs文件

package com.lijun.feign.interfaces;

import com.lijun.feign.config.FeignConfiguration;
import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

/**
 * Feign客户端调用接口
 * @author ljl
 *
 */
@FeignClient(value = "springcloud-eurekaClient",configuration = FeignConfiguration.class)
public interface EurekaClientFeign {

   /**
    * 调用远程服务器的方法
    * 服务器即为上述注解@FeignClient的value = "ppl-server"
    * @param name
    * @return
    */
   @GetMapping("/hello")
   String sayHiFromRemote(@RequestParam(value = "name") String name);
}

1.6.6 Hiservice.cs文件

package com.lijun.feign.service;


import com.lijun.feign.interfaces.EurekaClientFeign;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class Hiservice {

   @Autowired
   EurekaClientFeign eureClientFeign;
   public String sayHi(String name){
      return eureClientFeign.sayHiFromRemote(name);
   }
}

1.6.7 HiController.cs文件

package com.lijun.feign.controller;


import com.lijun.feign.service.Hiservice;
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;

@RestController
public class HiController {

   @Autowired
   Hiservice hiService;
   
   /**
    * 在该接口调用了Hiservice的sayHi()方法，Hiservice通过接口EurekaClientFeign远程
    * 调用 springcloud-eurekaClient 项目 ComputeController.cs中的 "/hello"
    * @param name
    * @return
    */
   @GetMapping("/hi")
   public String sayHi(@RequestParam(defaultValue="Feifn-client-test",required=false)String name){
      return hiService.sayHi(name);
   }
}

1.6.8 启动结果

启动main方法后，通过EurekaServer的监控页面可以看到又多了一个名称为SPRINGCLOUD-FEIGNCLIENT的节点； 此时可以通过http://localhost:8999/hi来查看执行结果。

1.7 结束

这就是spring cloud 的简单示例，在此感谢 https://blog.csdn.net/icarusliu/article/details/79461012 博主，如果需要代码，请关注公众号，发送“springcloud”，获取下载地址