微服务介绍及SpringCloud入门

最新推荐文章于 2025-08-21 16:10:06 发布

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本文探讨了单体应用架构的局限性和微服务架构的优势，包括独立开发、部署和服务自治原则。通过Spring Cloud实现微服务架构，展示了如何构建服务提供者和消费者，涉及实体类、DAO层、Controller层及YAML配置。

单体应用架构比较容易部署、测试、在项目的初期，单体应用可以很好的运行，但是需求的增加，代码库的增长出现很多问题

复杂性高，模块太多，便捷模糊、依赖关系不清晰、代码质量参差不齐、修改容易带来隐含缺陷
技术债务，时间推移、人员更迭、不坏不修，一修就出问题
部署频率低，代码量多，构建和部署时间长。全量部署耗时间、影响范围大、风险高。
可靠性差，某个BUG可能导致整个系统瘫痪
扩展能力受限，单体应用作为一个整体进行扩展，无法根据业务模块的需要进行伸缩。
阻碍技术创新，每个成员都使用相同的语言和框架

什么是微服务架构？

微服务架构风格是一种将单一应用程序开发为一组小型服务的方法，每个服务运行在自己的进程中，服务间通信采用轻量级通信机制（通常用HTTP资源API）。这些服务围绕业务能力构建并且可通过全自动部署机制独立部署。这些服务共用一个最小型的集中式的管理，服务可用不同的语言开发，使用不同的存储技术

每个服务可以运行在自己的进程里
一系列独立运行的微服务共同构建起整个系统
每个服务为独立的开发业务，一个微服务只关注某个特定的功能
微服务之间通过一些轻量的通信机制进行通信，列如RESTful API
可以使用不同的语言和存储技术
全自动部署机制

微服务架构的优点

易于开发和维护
单个微服务启动较快
局部修改容易部署
技术栈不受限
按需伸缩

面临的挑战

运维要求高
分布式固有的复杂性
接口调整成本高
重复劳动

微服务设计原则

单一职责原则
服务自治原则
轻量级通信机制
微服务粒度

微服务开发框架——Spring Cloud

springcloud的特点

约定优于配置
适用于各种环境
隐藏了组件的复杂性
开箱即用
轻量级的组件
组件丰富，功能齐全
选型中立、丰富，
灵活，开发人员可按需灵活挑选技术选型

简单的实战微服务

第一步、编写服务提供者

使用spring data jpa做持久层，H2作为数据库

ArtifactId:microservice-simple-provider-user

pom文件

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <!--pom文件遵循的maven的哪个版本-->
    <modelVersion>4.0.0</modelVersion>
    <!--引入spring boot 依赖-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.guxilong</groupId>
    <artifactId>microservice-simple-provider-user</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>microservice-simple-provider-user</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

        <!--自动天家tomcat.springmvc的依赖自动配置-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--dao层框架-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!--h2内存数据库-->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--测试类依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
    </dependencies>
    <!--引入spring cloud依赖-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Edgware.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <!--maven插件-->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

在classpath下建schema.sql

drop table user if exists;
create table user (
id bigint generated by default as identity,
username varchar(40),
name varchar(20),
age int(3),
balance decimal(10,2),
primary key (id));

data.sql

insert into user (id, username, name, age, balance) values (1, 'account1', '张三', 20, 100.00);
insert into user (id, username, name, age, balance) values (2, 'account2', '李四', 28, 180.00);
insert into user (id, username, name, age, balance) values (3, 'account3', '王五', 32, 280.00);

Entry类

package com.guxilong.entity;

import java.math.BigDecimal;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class User {
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private Long id;
  @Column
  private String username;
  @Column
  private String name;
  @Column
  private Integer age;
  @Column
  private BigDecimal balance;

  public Long getId() {
    return this.id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getUsername() {
    return this.username;
  }

  public void setUsername(String username) {
    this.username = username;
  }

  public String getName() {
    return this.name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Integer getAge() {
    return this.age;
  }

  public void setAge(Integer age) {
    this.age = age;
  }

  public BigDecimal getBalance() {
    return this.balance;
  }

  public void setBalance(BigDecimal balance) {
    this.balance = balance;
  }

}

dao层

package com.guxilong.dao;

import com.guxilong.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
}

controller层

package com.guxilong.controller;

import com.guxilong.dao.UserRepository;
import com.guxilong.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {
    @Autowired
    private UserRepository userRepository;

    @GetMapping("/{id}")
    public User findById(@PathVariable Long id) {
        User findOne = this.userRepository.findById(id).orElse(null);
        return findOne;
    }
}

yml文件

server:
  port: 8000
spring:
  jpa:
    generate-ddl: false
    show-sql: true
    hibernate:
      ddl-auto: none
  datasource:                           # 指定数据源
    platform: h2                        # 指定数据源类型
    schema: classpath:schema.sql        # 指定h2数据库的建表脚本
    data: classpath:data.sql            # 指定h2数据库的数据脚本
logging:                                # 配置日志级别，让hibernate打印出执行的SQL
  level:
    root: INFO
    org.hibernate: INFO
    org.hibernate.type.descriptor.sql.BasicBinder: TRACE
    org.hibernate.type.descriptor.sql.BasicExtractor: TRACE

## INFO
info:
  app:
    name: @project.artifactId@
    encoding: @project.build.sourceEncoding@
    java:
      source: @java.version@
      target: @java.version@
management:
  security:
    enabled: false

访问http://localhost:8000/1

第二步、编写服务消费者

ArtifactId:microservice-simple-consumer-movie

pom文件

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.guxilong</groupId>
    <artifactId>microservice-simple-consumer-movie</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>microservice-simple-consumer-movie</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <!--自动天家tomcat.springmvc的依赖自动配置-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>
    <!--引入spring cloud依赖-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Edgware.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

实体类pojo

package com.guxilong.entity;

import java.math.BigDecimal;

public class User {
    private Long id;
    private String username;
    private String name;
    private Integer age;
    private BigDecimal balance;

    public Long getId() {
        return this.id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return this.username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return this.age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public BigDecimal getBalance() {
        return this.balance;
    }

    public void setBalance(BigDecimal balance) {
        this.balance = balance;
    }
}

启动类

package com.guxilong;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
public class MicroserviceSimpleConsumerMovieApplication {
	@Bean
	public RestTemplate restTemplate(){
		return new RestTemplate();
	}

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

}

@Bean是一个方法注解，作用是实例化一个Bean并使用该方法的名称命名。在本例中，添加@Bean注解的restTemplate方法，等价于RestTmeplate restTemplate = new RestTmeplate ();

创建controller

package com.guxilong.controller;

import com.guxilong.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

/**
 * Created by gu_xi on 2019/11/14.
 */
@RestController
public class MovieController {
    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/user/{id}")
    public User findById(@PathVariable Long id) {
        return restTemplate.getForObject("http://localhost:8000/" + id, User.class);
    }

}

application.yml

server:
  port: 8010

结果

http://localhost:8010/user/1

{"id":1,"username":"account1","name":"张三","age":20,"balance":100.00}