1 微服务入门

微服务概念

[引用]

Microservice architectures are the ‘new normal’. Building small, self-contained, ready to run applications can bring great flexibility and added resilience to your code. Spring Boot’s many purpose-built features make it easy to build and run your microservices in production at scale. And don’t forget, no microservice architecture is complete without Spring Cloud ‒ easing administration and boosting your fault-tolerance.

[说明]

• 微服务是一种架构模式，提倡将单一应用程序划分成一组小的服务，服务之间互相协调、互相配合，为用户提供最终价值。
• 每个服务运行在其独立的进程中，服务之间采用轻量级的通信机制互相协作。
• 每个服务都围绕具体业务构建，并且能够独立的部署到生产环境、类生产环境等。

SpringCloud

分布式微服务架构的一站式解决方案，是多种微服务架构落地技术的集合体

Spring Cloud can help with service discovery, load-balancing, circuit-breaking, distributed tracing, and monitoring. It can even act as an API gateway.

QuickStart

请记住：

约定 > 配置 > 编码

微服务基础环境搭建

1.新建maven工程

2.检查字符编码是否正确

3.注解生效激活

4.检查jdk配置

5.配置依赖

<?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.cyan</groupId>
    <artifactId>cloud</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>pom</packaging>

    <!-- 统一管理jar包版本 -->
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <junit.version>4.12</junit.version>
        <log4j.version>1.2.17</log4j.version>
        <lombok.version>1.16.18</lombok.version>
        <mysql.version>5.1.47</mysql.version>
        <druid.version>1.1.16</druid.version>
        <mybatis.spring.boot.version>1.3.0</mybatis.spring.boot.version>
    </properties>

    <!-- 子模块继承后：锁定版本+子模块无需写组名和版本号 -->
    <dependencyManagement>
        <dependencies>
            <!-- springboot 2.2.2 -->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.2.2.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!-- SpringCloud Hoxton.SR1-->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!-- SpringCloud Alibaba 2.1.0 RELEASE -->
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.1.0.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!-- mysql -->
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>${mysql.version}</version>
                <scope>runtime</scope>
            </dependency>
            <!-- druid-->
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>druid</artifactId>
                <version>${druid.version}</version>
            </dependency>
            <!-- mybatis -->
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>${mybatis.spring.boot.version}</version>
            </dependency>
            <!-- junit -->
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>${junit.version}</version>
            </dependency>
            <!-- log4j -->
            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>${log4j.version}</version>
            </dependency>
            <!-- lombok -->
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>${lombok.version}</version>
                <optional>true</optional>
            </dependency>
        </dependencies>
    </dependencyManagement>

</project>

dependencyManagement

• maven使用dependencyManagement来提供一种管理依赖版本号的方式，通常在一个组织或项目的最顶层的父POM看到dependencyManagement元素

• 使用pom.xml中的dependencyManagement元素能让所有在子项目中引用一个依赖而不用显示列出版本号，maven会沿着父子层次向上走，直到找到一个拥有dependencyManagement元素的项目，然后它就会使用dependencyManagement元素指定的版本号

• 多个子项目引用同样依赖，可以避免在每个子项目中声明一个版本号，若升级或切换其他版本号，仅需要在顶层父容器更新，不需要一个一个子项目的修改；另外若某子项目需要另外版本，仅需要声明version

• dependencyManagement只是声明依赖，并不实现引入，因此项目需要显示声明需要的依赖若不在子项目中声明依赖，是不会从父项目中继承下来的；

• 只有在子项目中写了该依赖，并且没有指定具体版本，才会从父项目中继承该项，并且version和scope都读取父pom

• 如果子项目中指定了版本号，那么会使用子项目中指定的jar版本

注意

父工程创建完成执行mvn:install将父工程发布到仓库方便子工程继承

支付模块搭建

微服务模块构建五部曲

1. 新建module
2. 引入POM
3. 配置YML
4. 添加主启动
5. 处理业务类

cloud-provider-payment-8001

1.新建cloud-provider-payment-8001

2.引入pom文件

• spring-cloud-starter-zipkin
• spring-boot-starter-web
• spring-boot-starter-actuator
• mybatis-spring-boot-starter
• druid-spring-boot-starter
• mysql-connector-java
• spring-boot-starter-jdbc
• lombok
• spring-boot-starter-test
• spring-cloud-starter-netflix-eureka-client

3.配置YML

server:
  port: 8001

spring:
  application:
    name: cloud-payment-service
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: org.gjt.mm.mysql.Driver
    url: jdbc:mysql://localhost:3306/db2019?useUnicode=true&characterEncoding=utf-8&useSSL=false
    username: root
    password: root


mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.cyan.springcloud.entities

4.添加主启动

@SpringBootApplication
public class PaymentMain8001 {
    public static void main(String[] args) {
        SpringApplication.run(PaymentMain8001.class, args);
    }
}

5.创建数据库

CREATE TABLE `payment` (
	`id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT'ID',
   `serial` varchar(200) DEFAULT'',
   PRIMARY KEY(`id`)
)ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8

6.处理业务逻辑

实体类

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Payment implements Serializable {

    private Long id;
    private String serial;
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class CommonResult<T> {

    private Integer code;
    private String message;
    private T data;

    public CommonResult(Integer code, String message) {
        this(code, message, null);
    }
}

数据访问层

@Mapper
public interface PaymentDao {

    int create(Payment payment);

    Payment getPaymentById(@Param("id") Long id);
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cyan.springcloud.dao.PaymentDao">
    <insert id="create" parameterType="Payment" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO payment(serial) VALUES(#{serial});
    </insert>

    <resultMap id="BaseResultMap" type="com.cyan.springcloud.entities.Payment">
        <id column="id" property="id" jdbcType="BIGINT"/>
        <id column="serial" property="serial" jdbcType="VARCHAR"/>
    </resultMap>
    <select id="getPaymentById" parameterType="Long" resultMap="BaseResultMap">
        SELECT * FROM payment WHERE id = #{id};
    </select>
</mapper>

业务逻辑层

public interface PaymentService {

    int create(Payment payment);

    Payment getPaymentById(Long id);
}

@Service
public class PaymentServiceImpl implements PaymentService {

    @Resource
    private PaymentDao paymentDao;

    @Override
    public int create(Payment payment) {
       return paymentDao.create(payment);
    }

    @Override
    public Payment getPaymentById(Long id) {
        return paymentDao.getPaymentById(id);
    }
}

控制器层

@Slf4j
@RestController
@RequestMapping(value = "/payment")
public class PaymentController {

    @Resource
    private PaymentService paymentService;

    @PostMapping(value = "/create")
    public CommonResult create(Payment payment) {
        int result = paymentService.create(payment);
        log.info("插入结果：{}", result);
        if (result > 0) {
            return new CommonResult(200, "Insert Success", result);
        } else {
            return new CommonResult(500, "Insert Failed", null);
        }
    }

    @GetMapping(value = "/get/{id}")
    public CommonResult getPaymentById(@PathVariable("id") Long id) {
        Payment payment = paymentService.getPaymentById(id);
        log.info("查询结果：{}", payment);

        if (payment != null) {
            return new CommonResult(200, "Query Success", payment);
        } else {
            return new CommonResult(404, "Query Failed" + id, null);
        }
    }
}

消费者订单模块构建

cloud-consumer-order-80

1.新建cloud-consumer-order-80

2.引入pom文件

• lombok

• spring-boot-starter-web

• spring-boot-starter-actuator
• spring-boot-starter-test

3.配置YML

server:
  port: 80

4.添加主启动

@SpringBootApplication
public class OrderMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderMain80.class, args);
    }
}

5.处理业务逻辑

实体类

• Payment
• CommonResult

RestTemplate

RestTemplate提供多种便捷访问远程Http服务的方法，是一种简单便捷的访问restful服务模板类，是Spring提供的用于访问Rest服务的客户端模板工具集

• 使用RestTemplate访问restful接口比较简单
• url 表示REST请求地址
• requestMap 表示请求参数
• ResponseBean.class 表示HTTP响应转换成的对象类型

配置类

@Configuration
public class ApplicationContextConfig {

    @Bean
    public RestTemplate getRestTemplate() {
        return new RestTemplate();
    }
}

接口层

@Slf4j
@RestController
@RequestMapping("/consumer")
public class OrderController {

    public static final String PAYMENT_URL = "http://localhost:8001";

    @Resource
    private RestTemplate restTemplate;

    @GetMapping("/payment/create")
    public CommonResult<Payment> create(Payment payment) {
        return restTemplate.postForObject(PAYMENT_URL + "/payment/create", payment, CommonResult.class);
    }

    @GetMapping("/payment/get/{id}")
    public CommonResult<Payment> getPayment(@PathVariable("id") Long id) {
        return restTemplate.getForObject(PAYMENT_URL + "/payment/get/" + id, CommonResult.class);
    }
}

抽取公共模块

发现问题：系统存在重复部分，需要进行重构

1.新建模块：cloud-api-commons

2.添加依赖

• lombok
• hutool-all

3.将公共部分封装进该模块

4.maven命令clean install

5.订单模块80和支付模块8001分别改造

• 删除各自原先的entities文件夹

• 添加依赖

  <dependency>
      <groupId>com.cyan</groupId>
      <artifactId>cloud-api-commons</artifactId>
      <version>${project.version}</version>
  </dependency>

附录

项目源码