1.工程搭建部署

方案一：完整工程导入

📎cloud.zip，如无法运行尝试换未编译版：📎cloud-demo.zip
下载解压上述工程，ide工具导入

方案二：从零开始搭建

1.工程与module创建

1.1 父工程创建

1.2 子module创建

module名称：order-service、user-service
无效文件夹删除，整体结构如图2

1.3 父pom资源引入

粘贴以下资源依赖，粘贴后maven会自动拉取依赖，如未拉取请手动刷新

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.3.9.RELEASE</version>
    <relativePath/>
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <spring-cloud.version>Hoxton.SR10</spring-cloud.version>
    <mysql.version>5.1.47</mysql.version>
    <mybatis.version>2.1.1</mybatis.version>
    <lombok.version>1.18.20</lombok.version>
</properties>

<dependencyManagement>
    <dependencies>
        <!-- springCloud -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        <!-- mysql驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>${mybatis.version}</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
        </dependency>
    </dependencies>
</dependencyManagement>

1.4 子module资源引入

user-service

order-service

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <!--mybatis-->
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

1.5 业务代码编写

1.user-service

application.yml配置文件

server:
  port: 8081
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/cloud_user?useSSL=false
    username: root
    password: root123456
    driver-class-name: com.mysql.jdbc.Driver
mybatis:
  type-aliases-package: cn.itcast.user.pojo
  configuration:
    map-underscore-to-camel-case: true
logging:
  level:
    cn.itcast: debug
  pattern:
    dateformat: MM-dd HH:mm:ss:SSS

|--mapper

|-- UserMapper

package cn.itcast.user.mapper;

import cn.itcast.user.pojo.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

/**
 * 用户持久层
 *
 * @author 
 * @date 2022-12-22 14:12
 */
public interface UserMapper {

    /**
     * 根据ID查找用户
     * @param id    用户ID
     * @return      用户实体信息
     */
    @Select("select * from tb_user where id=#{id}")
    User findById(@Param("id") Long id);
}

|--pojo

|-- User

package cn.itcast.user.pojo;

import lombok.Data;

/**
 * 用户实体
 *
 * @author 
 * @date 2022-12-22 14:07
 */
@Data
public class User {

    /**
     * 主键ID
     */
    private Long id;

    /**
     * 用户姓名
     */
    private String username;

    /**
     * 用户地址
     */
    private String address;
}

|--service

|-- UserService

package cn.itcast.user.service;

import cn.itcast.user.mapper.UserMapper;
import cn.itcast.user.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.Objects;

/**
 * 用户业务层
 *
 * @author 
 * @date 2022-12-22 14:13
 */
@Service
public class UserService {

    @Autowired
    private UserMapper userMapper;

    /**
     * 根据ID查找用户
     * @param id    用户ID
     * @return      用户实体信息
     */
    public User findById(Long id) {
        if (Objects.isNull(id)) {
            return null;
        }
        return userMapper.findById(id);
    }

}

|--web

|-- UserController

package cn.itcast.user.web;

import cn.itcast.user.pojo.User;
import cn.itcast.user.service.UserService;
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.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * 用户控制层
 *
 * @author 
 * @date 2022-12-22 14:15
 */
@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;

    /**
     * 根据ID查找用户
     * @param id    ID
     * @return      用户信息
     */
    @GetMapping("/{id}")
    public User findById(@PathVariable("id") Long id) {
        return userService.findById(id);
    }
}

|--UserApplication

package cn.itcast.user;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * 启动类
 *
 * @author 
 * @date 2022-12-22 14:00
 */
@MapperScan("cn.itcast.user.mapper")
@SpringBootApplication
public class UserApplication {

    public static void main(String[] args) {
        SpringApplication.run(UserApplication.class, args);
        System.out.println("用户工程启动成功");
    }
}

2.order-service

application.yml配置文件

server:
  port: 8080
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/cloud_order?useSSL=false
    username: root
    password: root123456
    driver-class-name: com.mysql.jdbc.Driver
mybatis:
  type-aliases-package: cn.itcast.order.pojo
  configuration:
    map-underscore-to-camel-case: true
logging:
  level:
    cn.itcast: debug
  pattern:
    dateformat: MM-dd HH:mm:ss:SSS

|--mapper

|-- OrderMapper

package cn.itcast.order.mapper;

import cn.itcast.order.pojo.Order;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

/**
 * 订单持久层
 *
 * @author 
 * @date 2022-12-22 14:22
 */
public interface OrderMapper {

    /**
     * 根据ID查找订单
     * @param id    订单ID
     * @return      订单对象
     */
    @Select("select * from tb_order where id=#{id}")
    Order findById(@Param("id")Long id);
}

|--pojo
|-- Order

package cn.itcast.order.pojo;

import lombok.Data;

/**
 * 订单实体(vo并非dto)
 *
 * @author 
 * @date 2022-12-22 14:19
 */
@Data
public class Order {

    /**
     * 主键ID
     */
    private Long id;

    /**
     * 用户主键ID
     */
    private Long userId;

    /**
     * 商品名称
     */
    private String name;

    /**
     * 商品价格
     */
    private Long price;

    /**
     * 商品数量
     */
    private Integer num;

    /**
     * 用户信息
     */
    private User user;
}

|-- User

package cn.itcast.order.pojo;

import lombok.Data;

/**
 * 用户实体
 *
 * @author 
 * @date 2022-12-22 14:07
 */
@Data
public class User {

    /**
     * 主键ID
     */
    private Long id;

    /**
     * 用户姓名
     */
    private String username;

    /**
     * 用户地址
     */
    private String address;
}

|--service

|-- OrderService

package cn.itcast.order.service;

import cn.itcast.order.mapper.OrderMapper;
import cn.itcast.order.pojo.Order;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * 订单业务层
 *
 * @author 
 * @date 2022-12-22 14:24
 */
@Service
public class OrderService {

    @Autowired
    private OrderMapper orderMapper;

    /**
     * 根据ID查找订单
     * @param id    订单ID
     * @return      订单对象
     */
    public Order findById(Long id) {
        Order order = orderMapper.findById(id);
        return order;
    }
}

|--web

|-- OrderController

package cn.itcast.order.web;

import cn.itcast.order.pojo.Order;
import cn.itcast.order.service.OrderService;
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.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * 订单控制层
 *
 * @author 
 * @date 2022-12-22 14:25
 */
@RestController
@RequestMapping("/order")
public class OrderController {

    @Autowired
    private OrderService orderService;

    /**
     * 根据ID查找订单
     * @param orderId    订单ID
     * @return           订单对象
     */
    @GetMapping("/{orderId}")
    public Order findById(@PathVariable("orderId")Long orderId) {
        return orderService.findById(orderId);
    }
}

|--OrderApplication

package cn.itcast.order;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * 启动类
 *
 * @author 
 * @date 2022-12-22 14:05
 */
@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
        System.out.println("订单工程启动成功");

    }
}

2.数据库导入

需参见上图新建两个数据库，然后导入DDL语句
📎cloud-order.sql
📎cloud-user.sql

导完如下

3.项目启动

3.1 启动并访问user-service

3.2 启动并访问order-service

观察发现，虽然order-service服务调用成功，但是里面的user对象却是空的。原因我们应该也可以了解到是因为User对象数据数存储在数据库：tb_user，而此工程连接数据库是：tb_order，查询此数据库时无法获取对应的User数据，怎么获取？获取的具体实现我们将在下一章节进一步铺开。

4.服务远程调用

分析现有链路调用关系可以发现：

http://localhost:8081/user/{id} 可以获取用户信息
http://localhost:8081/order/{orderId} 可以获取订单信息，但是用户信息为空

想要订单信息中返回用户信息，只要在获取订单链路中追加对用户信息的获取、返回值的组装即可，由此引申出微服务之间的远程服务调用，具体调整可见下图。

时序图说明

上述图形为时序图，一般用来描述系统与系统之间的交互流程，主要是交互API、代码顺序、参数一般忽略，时序图不同于业务流程，更关注业务实现过程中系统前后依赖，数据请求与返回，以下为笔者实际工作场景示例：

服务远程调用实现

注入RestTemplate

此处推荐一个小的优雅工具：https://carbon.now.sh/

RestTemplate完成远程服务调用

在此笔者除了完成远程服务调用，同时对代码做了结构化、异常校验、函数封装。虽然此处逻辑并不复杂，但是对于主干逻辑简化和代码风格，希望能起到一个引导作用。

package cn.itcast.order.service;

import cn.itcast.order.mapper.OrderMapper;
import cn.itcast.order.pojo.Order;
import cn.itcast.order.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import java.util.Objects;

/**
* 订单业务层
*
* @author 
* @date 2022-12-22 14:24
*/
@Service
public class OrderService {

    @Autowired
    private OrderMapper orderMapper;

    @Autowired
    private RestTemplate restTemplate;

    /**
     * 根据ID查找订单
     * @param id    订单ID
     * @return      订单对象
     */
    public Order findById(Long id) {

        // step 1 : 查询订单原始数据
        Order order = orderMapper.findById(id);
        if (Objects.isNull(order)) {
            return null;
        }

        // step 2 : 查询用户数据
        User user = queryUserInfoById(order.getUserId());

        // step 3 : 组装用户数据
        if (Objects.nonNull(user)) {
            order.setUser(user);
        }

        // step 4: 数据返回
        return order;
    }

    /**
     * 根据用户ID查找用户信息
     * @param userId    用户ID
     * @return          用户信息
     */
    private User queryUserInfoById(Long userId) {
        String url = "http://localhost:8081/user/" + userId;
        return restTemplate.getForObject(url, User.class);
    }
}

SpringCloud工程部署启动