springcloud各个组件使用demo

Eureka服务注册中心

创建三个eureka服务注册中心,分别为:

eureka-server1

spring:
  application:
    name: eureka-server1
server:
  port: 8001

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8002/eureka/,http://localhost:8003/eureka/
    fetch-registry: true
    register-with-eureka: true

eureka-server2

server:
  port: 8002
spring:
  application:
    name: eureka-server2
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/,http://localhost:8003/eureka/
    register-with-eureka: true
    fetch-registry: true

eureka-server3

server:
  port: 8003
spring:
  application:
    name: eureka-server3
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/,http://localhost:8002/eureka/
    fetch-registry: true
    register-with-eureka: true

三个服务注册中心的pom.xml内容一样, 都如下:

<?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">
    <parent>
        <artifactId>springboot-microservice-parent</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>eureka-server3</artifactId>

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

</project>

其中父pom.xml文件内容如下:

<?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>org.example</groupId>
    <artifactId>springboot-microservice-parent</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>eureka-server1</module>
        <module>eureka-server2</module>
        <module>eureka-server3</module>
        <module>goods</module>
        <module>goods2</module>
        <module>ribbon-client</module>
    </modules>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.6</version>
        <relativePath/>
    </parent>

    <dependencyManagement>
        <dependencies>
            <!--根据springboot的版本指定springCloud的版本-->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>2020.0.6</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

</project>

eureka-server1、eureka-server2、eureka-server3入口代码相同,都如下:

入口类的类名不同,其他都相同:

EurekaServer1Application.java

EurekaServer2Application.java

EurekaServer3Application.java

package com.example;

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

@SpringBootApplication
@EnableEurekaServer
public class EurekaServer1Application {
    public static void main(String[] args) {
        SpringApplication.run(EurekaServer1Application.class, args);
    }
}

代码结构图

Eureka客户端

① goods微服务(扮演eureka客户端角色)

application.yaml

server:
  port: 9001
spring:
  application:
    name: goods-server
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/,http://localhost:8002/eureka/,http://localhost:8003/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">
    <parent>
        <artifactId>springboot-microservice-parent</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>goods</artifactId>

    <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.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>
    </dependencies>


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

</project>

入口文件

GoodsApplication.java

package com.example;

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

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

测试控制器类: GetGoodsController.java

package com.example.controller;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/goods")
public class GetGoodsController {

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

    @RequestMapping("/getOne")
    public String getOneGoods() {
        return "返回一条数据"+String.valueOf(port);
    }
}

②goods2微服务(扮演eureka客户端角色), 同goods微服务完全一样

goods2和goods的监听端口不同,其他都一样

goods2的 application.yaml如下:

server:
  port: 9002
spring:
  application:
    name: goods-server
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/,http://localhost:8002/eureka/,http://localhost:8003/eureka/

启动eureka-server1 eureka-server2 eureka-server3服务端, 再启动goods goods2客户端后, 访问 http://localhost:8001, http://localhost:80012, http://localhost:8003 如下:

可以看到, 各个微服务都已经注册到注册中心了; 其中的微服务RIBBON-SERVER是后面要演示的负载均衡调用组件

负载均衡调用组件 Ribbon

pom.xml

一定要避开一个坑: Ribbon组件和Eureka-client不要同时引入

<?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">
    <parent>
        <artifactId>springboot-microservice-parent</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>ribbon-client</artifactId>

    <dependencies>
        <!-- eureka-client 已经集成了loadbalanced了,不需要在引入ribbon了,否则引起会冲突,但是启动的时候也不报这个冲突的错误,这里一定要避开这个坑!!!,否则后面调试让你头大,报错一直找不到微服务GOODS-SERVER实例 -->
        <!--<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
            <version>2.2.4.RELEASE</version>
        </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-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>
    </dependencies>

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

</project>

application.yaml

server:
  port: 10001
spring:
  application:
    name: ribbon-server
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8001/eureka/,http://localhost:8002/eureka/,http://localhost:8003/eureka/

微服务入口文件RibbonClientApplication.java

入口类上不要再标注@RibbonClient注解了

package com.example;

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

@SpringBootApplication
@EnableEurekaClient
// @RibbonClient(name = "GOODS-SERVER") //eureka-client组件已经引入了loadbalance了, 不需要在导入ribbon组件了
public class RibbonClientApplication {
    public static void main(String[] args) {
        SpringApplication.run(RibbonClientApplication.class, args);
    }
}

配置文件MyRestTemplate.java

package com.example.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class MyRestTemplate {

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

控制器BalanceRequest.java

package com.example.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.util.List;

/**
 * 测试 ribbon负载均衡远程调用
 */
@RestController
@RequestMapping("/ribbon")
public class BalanceRequest {

    @Autowired
    private DiscoveryClient discoveryClient;

    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @Autowired
    private RestTemplate restTemplate;//根据类型,会导入我们自己定义的MyRestTemplate类

    @RequestMapping("getGoods")
    public String getGoods() {
        //方式一:
        // RestTemplate restTemplate = new RestTemplate();
        // String forObject = restTemplate.getForObject("http://localhost:9001/goods/getOne", String.class);
        // System.out.println(forObject);
        // return forObject;

        //方式二
        //getServices()获取所有注册在注册中心的服务
        // List<String> services = discoveryClient.getServices();
        // for (String service : services) {
        //     System.out.println(service);
        // }

        //获取某个服务id下的所有信息
        // List<ServiceInstance> instances = discoveryClient.getInstances("GOODS-SERVER");
        // for (ServiceInstance instance : instances) {
        //     System.out.println(instance.getHost());
        //     System.out.println(instance.getPort());
        //     // System.out.println(instance.getMetadata());
        //     System.out.println(instance.isSecure());
        //     System.out.println(instance.getUri().toString());
        //     System.out.println(instance.getServiceId());
        //     System.out.println(instance.getScheme());
        // }

        // RestTemplate restTemplate = new RestTemplate();
        // // String forObject = restTemplate.getForObject(instances.get(0).getUri() + "/goods/getOne", String.class);
        // String forObject = restTemplate.getForObject(instances.get(1).getUri() + "/goods/getOne", String.class);
        // return forObject;

        //方式三: 坑!! 一直报错: loadBalancerClient.choose("goods-server")返回null, 原因就是同时导入了ribbon依赖,又有eureka-client依赖; eureka-client包中已经有了ribbon核心组件中的loadbalanced了,不需要再导入ribbon了
        // System.out.println("********************");
        // System.out.println(loadBalancerClient);
        // System.out.println(loadBalancerClient.choose("goods-server"));
        // System.out.println(loadBalancerClient.choose("GOODS-SERVER"));
        // System.out.println("********************");
        //
        // ServiceInstance choose = loadBalancerClient.choose("GOODS-SERVER");
        // ServiceInstance choose2 = loadBalancerClient.choose("goods-server");
        //
        // System.out.println("++++++++++++++++++++++");
        // System.out.println(choose);
        // System.out.println(choose2);
        // System.out.println(choose.getUri().toString());
        // System.out.println(choose.getHost());
        // System.out.println(choose.getPort());
        // System.out.println("++++++++++++++++++++++");

        // ServiceInstance choose = loadBalancerClient.choose("GOODS-SERVER");
        // RestTemplate restTemplate = new RestTemplate();
        // String forObject = restTemplate.getForObject(choose.getUri() + "/goods/getOne", String.class);
        // System.out.println(forObject);
        // return forObject;

        //方式四://如果不清楚eureka-client已经内置导入了loadbalance了,而再次导入Ribbon组件的话,将一直报错:找不到服务...: No instances available for GOODS-SERVER,坑!!!
        String forObject = restTemplate.getForObject("http://goods-server/goods/getOne", String.class);
        System.out.println(forObject);
        return forObject;
    }
}

代码接口图如下:

postman测试结果如下:

默认轮询的方式展示返回结果

第一次请求返回9001	再次请求返回9002