一、服务拆分（order-service、user-service）

1.创建数据库

#订单表
CREATE TABLE `tb_order` (
  `id` int NOT NULL AUTO_INCREMENT COMMENT 'id',
  `ordername` varchar(255) DEFAULT NULL COMMENT '订单名称',
  `price` int DEFAULT NULL COMMENT '价格',
  `num` int DEFAULT NULL COMMENT '数量',
  `userId` int DEFAULT NULL COMMENT '用户id',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb3

#用户表
CREATE TABLE `tb_user` (
  `id` int NOT NULL AUTO_INCREMENT COMMENT 'id',
  `username` varchar(255) DEFAULT NULL COMMENT '用户名',
  `address` varchar(255) DEFAULT NULL COMMENT '地址',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8mb3

2.创建order-service和user-service模块，引入依赖

父模块：

<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>8.0.25</mysql.version>
    <mybatis.version>2.1.3</mybatis.version>
</properties>

<!-- dependencyManagement 只对依赖版本进行管理，不会实际引入 jar -->
<dependencyManagement>
    <dependencies>
        <!-- springCloud 此处使用 <scope>import</scope>意味着导入了springCloud父模块的jar包依赖-->
        <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>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
</dependencies>

order-service模块：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>com.keqing</groupId>
        <artifactId>order-user</artifactId>
        <version>1.0-SNAPSHOT</version>
        <scope>compile</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

user-service模块：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

3、order-service各层代码

pojo：

@Data
public class Order {
    private Integer id;
    private String ordername;
    private Integer price;
    private Integer num;
    private Integer UserId;
    private User user;
}

mapper：

@Mapper
public interface OrderMapper {
    /**
     * 根据id查询订单
     */
    @Select("select * from tb_order where id = #{id}")
    Order getById(@Param("id") Long id);
}

service：

public interface OrderService {
    /**
     * 根据id查找订单
     */
    Order selectById(Long id);
}

service.impl：

@Service
public class OrderServiceImpl implements OrderService {

    @Autowired
    private OrderMapper orderMapper;

    @Autowired
    private RestTemplate restTemplate;

    /**
     * 根据id查找订单
     */
    @Override
    public Order selectById(Long id) {
        //1.查询订单
        Order order = orderMapper.getById(id);
        //2.利用RestTemplate发起http请求，查询用户
        //2.1 url路径
        String url = "http://userservice/user/" + order.getUserId();
        //2.2 发起http请求，将JSON反序列化为User对象
        User user = restTemplate.getForObject(url,User.class);
        order.setUser(user);
        return order;
    }
}

controller：

@RestController
@RequestMapping("/order")
public class OrderController {

    @Autowired
    private OrderService orderService;

    @GetMapping("/{id}")
    public Order selectOrder(@PathVariable("id") Long id){
        return orderService.selectById(id);
    }
}

config：

@Component
public class RestTemplateConfig {

    /**
     * 创建 RestTemplate 并注入 Spring 容器
     * @LoadBalanced 注解描述：负载均衡作用
     */
    @LoadBalanced
    @Bean
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

4、user-service各层代码

pojo：

@Data
public class User {
    private Integer id;
    private String username;
    private String address;
}

mapper：

@Mapper
public interface UserMapper {

    @Select("select * from tb_user where id = #{id}")
    User getById(@Param("id") Long id);
}

service：

public interface UserService {
    User selectById(Long id);
}

service.impl：

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Override
    public User selectById(Long id) {
        return userMapper.getById(id);
    }
}

controller：

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserService userService;


    @GetMapping("/{id}")
    public User select(@PathVariable("id") Long id){
        return userService.selectById(id);
    }
}