初步搭建springcloud(上)

本文是关于初步搭建springcloud的教程,涵盖了从基础环境搭建到服务发现(Eureka)、客户端负载均衡(Ribbon)以及应用通信(Feign)。首先介绍了如何创建springcloud项目,包括提供方和服务消费方的配置。接着详细讲解了Eureka服务器的注册与发现机制,以及Ribbon的负载均衡策略,包括轮询、随机、响应时间和区域感知轮询等。最后提到了Feign的声明式服务调用,以及如何解决接口暴露和消费端扫描的问题。

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sptingcloud官方文档
https://spring.io/projects/spring-cloud

springcloud中文文档
https://springcloud.cc/spring-cloud-dalston.html

一、搭建基础springcloud
二、服务发现:Eureka服务器
三、客户端负载均衡:ribbon
四、应用通信:feign

一、搭建基础springcloud


由于springcloud是基于http的所以它不用将接口提取出来建立一个容器

父工程

<?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.besteam</groupId>
    <artifactId>besteamcloud</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>pom</packaging>
    <properties>
        <dept-api.version>1.0-SNAPSHOT</dept-api.version>

        <lombok.version>1.16.18</lombok.version>
        <junit.version>4.12</junit.version>
        <log4j.version>1.2.17</log4j.version>
        <lombok.version>1.16.18</lombok.version>
    </properties>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>1.5.9.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.0.4</version>
            </dependency>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>1.0.31</version>
            </dependency>
            <dependency>
                <groupId>com.baomidou</groupId>
                <artifactId>mybatis-plus-boot-starter</artifactId>
                <version>3.0.5</version>
            </dependency>
            <dependency>
                <groupId>ch.qos.logback</groupId>
                <artifactId>logback-core</artifactId>
                <version>1.2.3</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>${junit.version}</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>${log4j.version}</version>
            </dependency>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>fastjson</artifactId>
                <version>1.2.53</version>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <modules>
        <module>dept-api</module>
        <module>dept-provider</module>
        <module>dept-consumer</module>
    </modules>
</project>

项目名:dept-api

核心内容:

/**
 * @author ginwu
 * @date 2019/1/19 10:22
 * @description
 */
@NoArgsConstructor
@AllArgsConstructor
@Data
@Accessors(chain=true)
@TableName(value = "dept")
public class Dept {

    @TableId(type = IdType.AUTO)
    private Long id;

    private String deptName;

    private String parentName;

    private Integer sort;

    private Date createTime;

}

提供方

  项目名:dept-provider

  核心内容:

<!-- 引用dept-api -->
<dependency>
    <groupId>org.besteam</groupId>
    <artifactId>dept-api</artifactId>
    <version>${dept-api.version}</version>
</dependency>
<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-config</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
package org.besteam.controller;

import org.besteam.entity.Dept;
import org.besteam.service.DeptService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * @author ginwu
 * @date 2019/1/19 10:31
 * @description
 */
@RestController
public class DeptController {

    @Autowired
    private DeptService deptService;

    /**
     * 通过id查询部门
     * @param id
     * @return
     */
    @RequestMapping(value = "/dept/get/{id}",method = RequestMethod.GET)
    public Dept getDept(@PathVariable("id") Long id){
        return deptService.getDeptById(id);
    }

    @RequestMapping(value = "/dept/all")
    public List<Dept> getDeptList(){
        return deptService.selectAll();
    }

    @RequestMapping(value = "/dept/add",method = RequestMethod.POST)
    public void add(Dept dept){
        deptService.add(dept);
    }

    @RequestMapping(value = "/dept/update")
    public void update(Dept dept){
        deptService.update(dept);
    }
}

yml

server:
  port: 8081

spring:
  application:
    name: dept-provider
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/besteamcloud
    username: root
    password: 123123
    initial-size: 1
    min-idle: 1
    max-active: 20
    test-on-borrow: true

mybatis-plus:
  mapper-locations:
    - class*:mapper/**/*Mapper.xml

消费方:

  项目名:consumer-dept

  核心内容:

/**
 * @author ginwu
 * @date 2019/1/19 16:50
 * @description
 */
@RestController
@RequestMapping("/consumer/dept")
public class DeptConsumerController {
    //单机测直接访问本地即可
    //@1
    private static final String REST_URL_PREFIX = "http://localhost:8081";

    //@3
    private static String REST_URL_LOADBALANCE = "http://DEPT-PROVIDER";

    @Autowired
    private RestTemplate restTemplate;
    //@2
    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @RequestMapping("/get/{id}")
    public String getDeptById(@PathVariable("id") Long id){
        //第一种访问方式@1
        Dept dept = restTemplate.getForObject(REST_URL_PREFIX+"/dept/get/"+id,Dept.class);

        //第二种访问方式@2
//        ServiceInstance serviceInstance = loadBalancerClient.choose("BESTEAMCLOUD-PROVIDER8081");
//        String url = String.format("http://%s:%s",serviceInstance.getHost(),serviceInstance.getPort());
//        Dept dept = restTemplate.getForObject(url+"/dept/get/"+id,Dept.class);
//
        //第三种访问方式@3
        //在config中的RestTemplate中添加@LoadBalaced
//        Dept dept = restTemplate.getForObject(REST_URL_LOADBALANCE+"/dept/get/"+id,Dept.class);
        return JSON.toJSONString(dept);
    }

    @RequestMapping("/all")
    public String getAll(){
        List<Dept> list = restTemplate.getForObject(REST_URL_PREFIX+"/dept/all",List.class);
        return JSON.toJSONString(list);
    }

}
package org.besteam.config;

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

/**
 * @author ginwu
 * @date 2019/1/19 17:34
 * @description
 */
@Configuration
public class CloudConfig {
    @Bean
//    @LoadBalanced
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

yml

server:
  port: 80

至此,一个基本的远程调用模块就已经完成了,接下带就是各种配置各种部署了

二、服务发现:Eureka服务器


eureka的概念在官网中已有说明,这里不再说明,只给句具体的实现和粗略的讲解:
注册、发现:就是把我们已经实现好的功能模块暴露给eureka,然后通过eureka去控制用户具体访问那个节点的模块,怎样去负载均衡等。

注册、发现服务:

  项目名:besteam-eureka

  核心内容:

<!-- eureka 服务端 -->
 <dependency>
     <groupId>org.springframework.cloud</groupId>
     <artifactId>spring-cloud-starter-eureka-server</artifactId>
 </dependency>
<!-- eureka  Finchley版本 -->
 <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>

@SpringBootApplication
@EnableEurekaServer // EurekaServer服务器端启动类,接受其它微服务注册进来
public class DeptEurekaApplication {

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

}
server:
  port: 7001

eureka:
  instance:
    hostname: besteamEureka7001.com #eureka服务端的实例名称
  client:
    register-with-eureka: false #false表示不向注册中心注册自己。
    fetch-registry: false #false表示自己端就是注册中心,我的职责就是维护服务实例,并不需要去检索服务
    service-url:
      defaultZone: http://localhost:7001/eureka/ #设置与Eureka Server交互的地址查询服务和注册服务都需要依赖这个地址。
      # defaultZone: http://localhost:7002/eureka/,defaultZone: http://localhost:7003/eureka/

另外需要将其他的微服务注册进来就需要在微服务中进行配置


  项目名:besteam-eureka

  核心内容:

<!-- 将consumer注册到eureka -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<!-- eureka  Finchley版本 -->
 <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
@SpringBootApplication
@EnableEurekaClient //注册到eureka服务
public class DeptProviderApplication {

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

}
server:
  port: 8081

spring:
  application:
    name: dept-provider

eureka:
  instance:
    instance-id: besteamcloud-provider8081
    prefer-ip-address: true     #访问路径可以显示IP地址
  client:
    service-url:
      defaultZone: http://localhost:7001/eureka #注册到eureka

三、客户端负载均衡:ribbon


之所以为客户端的负载均衡是因为它是为消费者所提供的,意思是所有的消费者都在注册中心列表中,当消费者需要访问时,注册中心会把相应服务的注册列表给客户端,有客户端去选择调用哪一个服务。而正对服务端的负载均衡就需要一个代理,有客户端提出访问,然后通过代理去找服务端,常见的服务端负载均衡Nginx、dubbo

ribbon实现的负载均衡有三点:
  1. 服务发现
  2. 服务选择规则
  3. 服务监听
  项目名:besteam-consumer
  核心内容:
package org.besteam.controller;

import com.alibaba.fastjson.JSON;
import org.besteam.entity.Dept;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.util.List;

/**
 * @author ginwu
 * @date 2019/1/19 16:50
 * @description
 */
@RestController
@RequestMapping("/consumer/dept")
public class DeptConsumerController {
    //单机测直接访问本地即可
    //@1
    private static final String REST_URL_PREFIX = "http://localhost:8081";

    //@3
    private static String REST_URL_LOADBALANCE = "http://DEPT-PROVIDER";

    @Autowired
    private RestTemplate restTemplate;
    //@2
    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @RequestMapping("/get/{id}")
    public String getDeptById(@PathVariable("id") Long id){
        //第一种访问方式@1
//        Dept dept = restTemplate.getForObject(REST_URL_PREFIX+"/dept/get/"+id,Dept.class);

        //第二种访问方式@2
//        ServiceInstance serviceInstance = loadBalancerClient.choose("BESTEAMCLOUD-PROVIDER8081");
//        String url = String.format("http://%s:%s",serviceInstance.getHost(),serviceInstance.getPort());
//        Dept dept = restTemplate.getForObject(url+"/dept/get/"+id,Dept.class);
//
        //第三种访问方式@3
        //在config中的RestTemplate中添加@LoadBalaced
        Dept dept = restTemplate.getForObject(REST_URL_LOADBALANCE+"/dept/get/"+id,Dept.class);
        return JSON.toJSONString(dept);
    }

    @RequestMapping("/all")
    public String getAll(){
        List<Dept> list = restTemplate.getForObject(REST_URL_PREFIX+"/dept/all",List.class);
        return JSON.toJSONString(list);
    }

}
package org.besteam.config;

import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
import org.apache.tomcat.util.digester.Rule;
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;

/**
 * @author ginwu
 * @date 2019/1/19 17:34
 * @description
 */
@Configuration
public class CloudConfig {
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }

    /**
     * 自定义访问规则,默认为轮询访问
     * ,此方法为随机访问
     * @return
     */
    @Bean
    public IRule iRule(){
        return new RandomRule();
    }
}
常用的几种访问规则有:
  1. 简单轮询负载均衡(RoundRobin)

    以轮询的方式依次将请求调度不同的服务器,即每次调度执行i = (i + 1) mod n,并选出第i台服务器。

  2. 随机负载均衡 (Random)

    随机选择状态为UP的Server

  3. 加权响应时间负载均衡 (WeightedResponseTime)

    根据相应时间分配一个weight,相应时间越长,weight越小,被选中的可能性越低。

  4. 区域感知轮询负载均衡(ZoneAvoidanceRule)

    复合判断server所在区域的性能和server的可用性选择server

Ribbon自带负载均衡策略比较
策略名策略声明策略描述
BestAvailableRulepublic class BestAvailableRule extends ClientConfigEnabledRoundRobinRule选择一个最小的并发请求的server
AvailabilityFilteringRulepublic class AvailabilityFilteringRule extends PredicateBasedRule过滤掉那些因为一直连接失败的被标记为circuit tripped的后端server,并过滤掉那些高并发的的后端server(active connections 超过配置的阈值)
WeightedResponseTimeRulepublic class WeightedResponseTimeRule extends RoundRobinRule根据相应时间分配一个weight,相应时间越长,weight越小,被选中的可能性越低。
RetryRulepublic class RetryRule extends AbstractLoadBalancerRule对选定的负载均衡策略机上重试机制。
RoundRobinRulepublic class RoundRobinRule extends AbstractLoadBalancerRuleroundRobin方式轮询选择server
RandomRulepublic class RandomRule extends AbstractLoadBalancerRule随机选择一个server
ZoneAvoidanceRulepublic class ZoneAvoidanceRule extends PredicateBasedRule复合判断server所在区域的性能和server的可用性选择server

四、应用通信:feign


feign是一个类似于伪RPC的应用之间的调用组件,实际上还是基于rest方式实现的,它的功能和ribbon类似,但它是以声明式的方式在客户端实现的

  项目名:besteam-consumer
  修改/添加内容:
<!-- feign -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
<!-- feign Finchley版本 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
package org.besteam.client;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * @author ginwu
 * @date 2019/1/23 20:33
 * @description]
 * 创建一个接口调用DEPT-PROVIDER服务中实现的方法
 */
@FeignClient(value = "DEPT-PROVIDER")
public interface InnerFeignClient {

    @GetMapping("/feign/get")
    public String feignTest();

}
package org.besteam.service;

import org.besteam.client.InnerFeignClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
/**
 * @author ginwu
 * @date 2019/1/23 20:40
 * @description
 * 实现调用feign远程调用的方法
 */
@Service
public class FeignTestService {
    @Autowired
    private InnerFeignClient innerFeignClient;

    public String foo(){
        String res = innerFeignClient.feignTest();
        if(null == res||"".equals(res)){
            return "test failure!!!";
        }
        return res;
    }
}

启动类添加@EnableFeignClients声明使用feign

@SpringBootApplication
@EnableEurekaClient //注册到eureka服务
@EnableFeignClients //声明feign
public class DeptConsumerApplication {

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

}
  项目名:besteam-consumer
  修改/添加内容:

按照正常些接口的方式实现

注意:到这里会发现,消费端调用服务端的接口,却要服务端去实现消费端需要暴露的接口,这显然不服务解耦合的思想,这个时候就需要把服务端的接口当做一个模块给暴露出来,或者在消费端中自己实现一个接口给暴露出来

实现方法如下:

  新建模块provider-api

  核心内容:

<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
<!-- feign Finchley版本 -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
package org.besteam.client;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * @author ginwu
 * @date 2019/1/23 20:33
 * @description]
 * 创建一个接口调用DEPT-PROVIDER服务中实现的方法
 */
@FeignClient(value = "DEPT-PROVIDER")
public interface InnerFeignClient {

    @GetMapping("/feign/get")
    public String feignTest();

}

这样我们就把消费方需要提供的接口给暴露出来了,就像rpc的做法一样,但是怎样才能让消费者方去扫描到这个接口呢?实现方式只需要在启动类的@EnableFeignClients上加一个包扫描:


  项目名: besteam-consumer

  修改/添加内容:

@SpringBootApplication
@EnableEurekaClient //注册到eureka服务
@EnableFeignClients(basePackages= {"org.besteam.client"}) //声明feign
public class DeptConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(DeptConsumerApplication.class, args);
    }
}
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