SpringCloud微服务项目快速搭建（一）（SpringCloud Netflix，H版-SR3）

一、前言

        Spring Cloud Netflix是Spring Cloud生态系统中的重要组成部分，也是使用Spring Cloud进行微服务架构开发的主要方向之一。Spring Cloud Netflix主要目标是为开发者提供构建分布式系统所需的组件，包括服务注册中心、负载均衡、断路器、转发器、过滤器等。二

二、创建SpringCloud Eureka

1.导入父项目依赖 父项目只用于管理项目不做代码处理

<?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>com.lzc</groupId>
  <artifactId>springcloud-netflix</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>pom</packaging>
  <modules>
    <module>pojo</module>
    <module>pojo/user-pojo</module>
    <module>server</module>
  </modules>


  <properties>
    <maven.compiler.source>8</maven.compiler.source>
    <maven.compiler.target>8</maven.compiler.target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <!--让当前项目变成一个springBoot的子项目-->
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.5.RELEASE</version>
  </parent>


  <!--父项目管理微服务的所有依赖，但是不引用，由子项目自己去引用自己要使用的依赖-->
  <dependencyManagement>
    <dependencies>
      <!-- spring cloud -->
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>Hoxton.SR3</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <dependencies>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
    </dependency>

  </dependencies>


</project>

 2.导入Eureka服务端组件依赖

<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>
    <parent>
        <groupId>com.lzc</groupId>
        <artifactId>springcloud-netflix</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>eureka-server</artifactId>
    <packaging>jar</packaging>

    <dependencies>
        <!--eureka-Server依赖，这个依赖不仅包含服务端依赖，还包含客户端依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <!--一个springboot项目想要跑起来，必须有spring-boot-starter-web依赖-->
    </dependencies>
</project>

 2.1配置启动类

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

/**
 * Hello world!
 */
@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApp {
    public static void main(String[] args) {
        SpringApplication.run(EurekaServerApp.class, args);
    }
}

 2.2配置yml

server:
  port: 8761 # 标识当前Eureka服务端的端口号

eureka:
  instance:
    hostname: localhost # 当前Eurek的实例名称
  client:
    registerWithEureka: false # 在客户端依赖中默认为true，所以服务端需要关闭
    fetchRegistry: false # 在客户端依赖中默认为true，所以服务端需要关闭
    serviceUrl: # http://localhost:8761/eureka/
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
  server:
    enable-self-preservation: false # 关闭Eureka自我保护机制

三、SpringCloud-Eureka客户端组件

1.导入依赖

<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>
    <parent>
        <groupId>com.lzc</groupId>
        <artifactId>server</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>user-server</artifactId>
    <packaging>jar</packaging>

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

    <dependencies>

        <!--引入Eureka的客户端依赖，不包含springboot-start-web，所以要单独引入-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!--引入springboot-start-web依赖，必须引入-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
   
    </dependencies>
</project>

 2.启动类

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

/**
 * Hello world!
 */
@SpringBootApplication
@EnableEurekaClient
public class UserServerApp {
    public static void main(String[] args) {
        SpringApplication.run(UserServerApp.class, args);
    }
}

3.配置yml

server:
  port: 1020 # 标识当前user服务端的端口号

eureka:
  client:
    serviceUrl: # http://localhost:8761/eureka/
      defaultZone: http://localhost:8761/eureka/
  instance:
    prefer-ip-address: true # 开启使用IP地址进行注册
    instance-id: ${spring.application.name}:${server.port} # 修改实例Id
spring:
  application: # 指定此服务的应用名称
    name: user-server

4.负载均衡

    @Bean
    @LoadBalanced// 开启负载均衡
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }

// 交给spring管理就能开启随机算法 这里直接@bean就行了
//    @Bean
//    public RandomRule randomRule(){
//        return new RandomRule();
//    }

5.集群

-Dserver.port=1021 -Deureka.instance.instance-id=user-server:1021 

四、引入OpenFeign

1.概述

        OpenFeign是一个声明式的Web服务客户端，是SpringCloud生态系统中负责服务间调用的一个服务调用工具。通过使用OpenFeign，我们可以方便地定义和调用RESTful服务，使得服务间调用变得简单、优雅，而且容易维护。它基于Netflix Feign库进行了扩展和改进，支持了更多的特性和功能。

2.导入依赖

     <!--引入OpenFeign依赖-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

3.配置yml

4.启动类加注解@EnableFeignClients

5.interface类

package com.lzc.feign;

import com.lzc.domain.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

// contextId FeignClient的唯一标识，推荐类名小驼峰
// path 映射路径 也可以requestMapping写在类上
// value 服务名称
@FeignClient(contextId = "userFeignClient",path = "user",value = "user-server")
public interface UserFeignClient {
    @GetMapping
    User getUser();
}

6.接口类自动注入直接调用

package com.lzc.controller;

import com.lzc.domain.User;
import com.lzc.feign.UserFeignClient;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/pay")
public class PayController {
    @Autowired
    private UserFeignClient userFeignClient;
    @GetMapping
    public User getUser(){
      return userFeignClient.getUser();
    }
}