服务注册与发现

概述

在这里，我们需要用的组件是 Spring Cloud Netflix 的 Eureka，Eureka 是一个服务注册和发现模块

创建服务注册中心

新建目录

新建pom



    4.0.0

    
        com.funtl
        hello-spring-cloud-dependencies
        1.0.0-SNAPSHOT
        ../hello-spring-cloud-dependencies/pom.xml
    

    hello-spring-cloud-eureka
    jar

    hello-spring-cloud-eureka
    http://www.suntong.com
    2019-Now

    
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
        

        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-server
        
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    
                    com.suntong.hello.spring.cloud.eureka.EurekaApplication

手动让maven管理此项目

创建源码目录

创建资源文件目录

新建配置文件

新建入口类

配置sdk

EurekaApplication.java

package com.suntong.hello.spring.cloud.eureka;

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

@SpringBootApplication
@EnableEurekaServer //开启Eureka服务端
public class EurekaApplication {
    public static void main(String[] args) {
        SpringApplication.run(EurekaApplication.class, args);
    }
}

application.yml

spring:
  application:
    name: hello-spring-cloud-eureka

server:
  port: 8761

eureka:
  instance:
    hostname: localhost
  client:
    registerWithEureka: false #不加这两句代表是客户端
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

pom.xml



    4.0.0

    
        com.funtl
        hello-spring-cloud-dependencies
        1.0.0-SNAPSHOT
        ../hello-spring-cloud-dependencies/pom.xml
    

    hello-spring-cloud-eureka
    jar

    hello-spring-cloud-eureka
    http://www.suntong.com
    2019-Now

    
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
        

        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-server
        
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    
                    com.suntong.hello.spring.cloud.eureka.EurekaApplication

运行入口类

Eureka Server 是有界面的，启动工程，打开浏览器访问：

http://localhost:8761

创建服务提供者

概述

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

构建项目

项目结构同之前一样

pom.xml



    4.0.0

    
        com.suntong
        hello-spring-cloud-dependencies
        1.0.0-SNAPSHOT
        ../hello-spring-cloud-dependencies/pom.xml
    

    hello-spring-cloud-service-admin
    jar

    hello-spring-cloud-service-admin
    http://www.suntong.com
    2018-Now

    
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
        

        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-server
        
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    com.funtl.hello.spring.cloud.service.admin.ServiceAdminApplication

ServiceAdminApplication.java

package com.suntong.hello.spring.cloud.service.admin;


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

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

application.yml

spring:
  application:
    name: hello-spring-cloud-service-admin

server:
  port: 8762

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

运行入口类

先启动服务端，再启动客户端

再下main工具栏service中点击

就可以启动run Dashboard

然后按顺序启动服务

服务注册与发现

新建controller提供服务

package com.suntong.hello.spring.cloud.service.admin.controller;


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

@RestController
public class AdminController {

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

    @RequestMapping(value = "hi", method = RequestMethod.GET)
    public String sayHi(String message){
        return String.format("Hi your message is : %s port : %s", message, port);
    }
}

重启，访问

创建服务消费者（Ribbon）

概述

在微服务架构中，业务都会被拆分成一个独立的服务，服务与服务的通讯是基于 http restful 的。Spring cloud 有两种服务调用方式，一种是 ribbon + restTemplate，另一种是 feign。在这一篇文章首先讲解下基于 ribbon + rest。

Ribbon 简介

Ribbon 是一个负载均衡客户端，可以很好的控制 http 和 tcp 的一些行为

构建项目

pom.xml



    4.0.0

    
        com.suntong
        hello-spring-cloud-dependencies
        1.0.0-SNAPSHOT
        ../hello-spring-cloud-dependencies/pom.xml
    

    hello-spring-cloud-web-admin-ribbon
    jar

    hello-spring-cloud-web-admin-ribbon
    http://www.suntong.com
    2019-Now

    
        
        
            org.springframework.boot
            spring-boot-starter-web
        
        
            org.springframework.boot
            spring-boot-starter-tomcat
        
        
            org.springframework.boot
            spring-boot-starter-thymeleaf
        
        
            org.springframework.boot
            spring-boot-starter-actuator
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
        

        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-server
        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-ribbon
        
        

        
        
            net.sourceforge.nekohtml
            nekohtml
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    com.suntong.hello.spring.cloud.web.admin.ribbon.WebAdminRibbonApplication

入口类

package com.suntong.hello.spring.cloud.web.admin.ribbon;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

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

application.yml

spring:
  application:
    name: hello-spring-cloud-web-admin-ribbon
  thymeleaf:
    cache: false
    mode: LEGACYHTML5
    encoding: UTF-8
    servlet:
      content-type: text/html

server:
  port: 8764

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

配置注入 RestTemplate 的 Bean，并通过 @LoadBalanced 注解表明开启负载均衡功能

package com.suntong.hello.spring.cloud.web.admin.ribbon.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 RestTemplateConfiguration {

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

再run - edit configuration里勾选上同时运行，模拟负载均衡效果

修改端口为空着的8763

在入口类再次启动

再次访问

创建测试用的 Service

package com.suntong.hello.spring.cloud.web.admin.ribbon.service;

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

@Service
public class AdminService {
    
    @Autowired
    private RestTemplate restTemplate;

    public String sayHi(String message) {
        return restTemplate.getForObject("http://hello-spring-cloud-service-admin/hi?message=" + message, String.class);
    }
    
}

创建测试用的 Controller

package com.suntong.hello.spring.cloud.web.admin.ribbon.controller;

import com.suntong.hello.spring.cloud.web.admin.ribbon.service.AdminService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class AdminController {

    @Autowired
    private AdminService adminService;

    @RequestMapping(value = "hi", method = RequestMethod.GET)
    public String sayHi(String message){
        return adminService.sayHi(message);
    }
}

运行服务消费者

访问

刷新

两台服务提供者工作，负载均衡

此时Eureka上两台服务提供者，一台服务消费者

此时的架构

一个服务注册中心，Eureka Server，端口号为：8761
service-admin 工程运行了两个实例，端口号分别为：8762，8763
web-admin-ribbon 工程端口号为：8764
web-admin-ribbon 通过 RestTemplate 调用 service-admin 接口时因为启用了负载均衡功能故会轮流调用它的 8762 和 8763 端口

创建服务消费者（Feign）

概述

Feign 是一个声明式的伪 Http 客户端，它使得写 Http 客户端变得更简单。使用 Feign，只需要创建一个接口并注解。它具有可插拔的注解特性，可使用 Feign 注解和 JAX-RS 注解。Feign 支持可插拔的编码器和解码器。Feign 默认集成了 Ribbon，并和 Eureka 结合，默认实现了负载均衡的效果
Feign 采用的是基于接口的注解
Feign 整合了 ribbon

创建服务消费者

项目结构

pom.xml



    4.0.0

    
        com.suntong
        hello-spring-cloud-dependencies
        1.0.0-SNAPSHOT
        ../hello-spring-cloud-dependencies/pom.xml
    

    hello-spring-cloud-web-admin-feign
    jar

    hello-spring-cloud-web-admin-feign
    http://www.suntong.com
    2019-Now

    
        
        
            org.springframework.boot
            spring-boot-starter-web
        
        
            org.springframework.boot
            spring-boot-starter-tomcat
        
        
            org.springframework.boot
            spring-boot-starter-thymeleaf
        
        
            org.springframework.boot
            spring-boot-starter-actuator
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
        

        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-server
        
        
            org.springframework.cloud
            spring-cloud-starter-openfeign
        
        

        
        
            net.sourceforge.nekohtml
            nekohtml
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    com.suntong.hello.spring.cloud.web.admin.feign.WebAdminFeignApplication

入口类

package com.suntong.hello.spring.cloud.web.admin.feign;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

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

配置文件application.yml

spring:
  application:
    name: hello-spring-cloud-web-admin-feign
  thymeleaf:
    cache: false
    mode: LEGACYHTML5
    encoding: UTF-8
    servlet:
      content-type: text/html

server:
  port: 8765

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

创建 Feign 接口

package com.suntong.hello.spring.cloud.web.admin.feign.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@FeignClient(value = "hello-spring-cloud-service-admin")
public interface AdminService {
    
    @RequestMapping(value = "hi", method = RequestMethod.GET)
    public String sayHi(String message);
    
}

创建测试用的 Controller

package com.suntong.hello.spring.cloud.web.admin.feign.controller;

import com.suntong.hello.spring.cloud.web.admin.feign.service.AdminService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class AdminController {

    @Autowired
    private AdminService adminService;

    @RequestMapping(value = "hi", method = RequestMethod.GET)
    public String sayHi(String message){
        return adminService.sayHi(message);
    }

}

运行消费者

访问发生错误，但是Eureka已经注册了

405-用来访问此页面的方法不被允许

给service接口加上@RequestParam注解

package com.suntong.hello.spring.cloud.web.admin.feign.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value = "hello-spring-cloud-service-admin")
public interface AdminService {

    @RequestMapping(value = "hi", method = RequestMethod.GET)
    public String sayHi(@RequestParam(value="message") String message);

}

重新启动

还是报错，发现controller注解错误，因为要返回对象到body，要使用@RestController注解而不是@Controller

package com.suntong.hello.spring.cloud.web.admin.feign.controller;

import com.suntong.hello.spring.cloud.web.admin.feign.service.AdminService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class AdminController {

    @Autowired
    private AdminService adminService;

    @RequestMapping(value = "hi", method = RequestMethod.GET)
    public String sayHi(String message){
        return adminService.sayHi(message);
    }

}

重启

访问http://localhost:8765/hi?message=HelloFeign

刷新

Spring Cloud Netflix 服务注册与发现

服务注册与发现

创建服务提供者

创建服务消费者（Ribbon）

创建服务消费者（Feign）

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