使用 SpringBoot + SpringCloud 简单体验分布式、负载均衡

一、前言
demo 级别

二、代码与结构
代码放在 github 上了：https://github.com/TheWays/springCloud.git

1、注册中心

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① RegisterApplication
仅添加注解：@EnableEurekaServer 的操作

package com.cun.register;

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

@EnableEurekaServer
@SpringBootApplication
public class RegisterApplication {

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

}

② application.yml 配置

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③ pom 依赖

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka-server</artifactId>
    </dependency>

④ 效果：http://localhost:9500
（红色框的内容为 Provider 启动后才有的）

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2、服务提供者

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① ProviderApplication （没改过）

package com.cun.provider;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ProviderApplication {

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

}

② MessageService

package com.cun.provider.service;

import org.springframework.stereotype.Service;

@Service
public class MessageService {

public String getMessage(){
    return "ITAEM";
}

}

③ MessageController

package com.cun.provider.controller;

import com.cun.provider.service.MessageService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MessageController {

@Autowired
MessageService messageService;

@GetMapping("/get")
public String getMessage(){
    return "provider提供信息："+messageService.getMessage();
}

}

④ application.yml 配置

server:
port: 9400
spring:
application:
name: provider-message

eureka:
instance:
prefer-ip-address: true # 注册服务的时候使用服务的ip地址
client:
service-url:
defaultZone: http://localhost:9500/eureka/

⑤ pom 依赖

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

⑥ 效果：http://localhost:9400/get

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3、服务消费者

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① ConsumerApplication
@EnableDiscoveryClient 开启发现服务功能、RestTemplate 使用负载均衡机制

package com.cun.consumer;

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

@EnableDiscoveryClient //开启发现服务功能
@SpringBootApplication
public class ConsumerApplication {

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

@LoadBalanced //使用负载均衡机制
@Bean
public RestTemplate restTemplate(){
    return new RestTemplate();
}

}

② MessageController

package com.cun.consumer.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class MessageController {

@Autowired
RestTemplate restTemplate;

@GetMapping("/show")
public String showMessage(){
    // 服务提供者url、返回数据类型
    String s = restTemplate.getForObject("http://provider-message/get", String.class);
    return "consumer获取信息："+s;
}

}

③ application.yml 配置

spring:
application:
name: consumer-message
server:
port: 9600

eureka:
instance:
prefer-ip-address: true # 注册服务的时候使用服务的ip地址
client:
service-url:
defaultZone: http://localhost:9500/eureka/

④ pom 依赖

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

⑤ 效果：http://localhost:9600/show

image.png