02-微服务的拆分规则和基于RestTemplate的远程调用

微服务的拆分与远程调用

创建父工程

任何分布式架构都离不开服务的拆分, 微服务也是一样 , 微服务的拆分遵守三个原则

• 微服务需要根据业务模块拆分,不同微服务不要重复开发相同业务
• 每个微服务都有自己独立的数据库, 不要直接访问其他微服务的数据库
• 微服务可以将自己的业务暴露为接口供其他微服务调用

创建父工程cloud-demo用来管理项目所需要的依赖的版本

• order-service订单微服务模块(工程): 负责订单相关业务,如根据订单Id查询订单
• user-service用户微服务模块(工程): 负责用户相关业务,如根据用户Id查询用户

<groupId>cn.itcast.demogroupId>
<artifactId>cloud-demoartifactId>
<version>1.0version>

<modules>
    <module>user-servicemodule>
    <module>order-servicemodule>
modules>
<packaging>pompackaging>


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


<properties>
    <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8project.reporting.outputEncoding>
    <java.version>1.8java.version>
    <spring-cloud.version>Hoxton.SR10spring-cloud.version>
    <mysql.version>5.1.47mysql.version>
    <mybatis.version>2.1.1mybatis.version>
properties>


<dependencyManagement>
    <dependencies>
        
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-dependenciesartifactId>
            <version>${spring-cloud.version}version>
            <type>pomtype>
            <scope>importscope>
        dependency>
        
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>${mysql.version}version>
        dependency>
        
        <dependency>
            <groupId>org.mybatis.spring.bootgroupId>
            <artifactId>mybatis-spring-boot-starterartifactId>
            <version>${mybatis.version}version>
        dependency>
    dependencies>
dependencyManagement>
<dependencies>
    <dependency>
        <groupId>org.projectlombokgroupId>
        <artifactId>lombokartifactId>
    dependency>
dependencies>
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创建订单微服务模块(工程)

第一步: 执行cloud-order.sql文件创建订单数据库,cloud-order的tb_order表中含有用户数据库的tb_user表的Id字段

@Data
public class Order {
    private Long id;
    private Long price;
    private String name;
    private Integer num;
    private Long userId;
    private User user;
}
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第二步: 配置order-service工程的pom.xml文件

<parent>
    <artifactId>cloud-demoartifactId>
    <groupId>cn.itcast.demogroupId>
    <version>1.0version>
parent>
<modelVersion>4.0.0modelVersion>
<artifactId>order-serviceartifactId>

<dependencies>
    <dependency>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-webartifactId>
    dependency>
    <dependency>
        <groupId>mysqlgroupId>
        <artifactId>mysql-connector-javaartifactId>
    dependency>
    
    <dependency>
        <groupId>org.mybatis.spring.bootgroupId>
        <artifactId>mybatis-spring-boot-starterartifactId>
    dependency>
dependencies>
<build>
    <finalName>appfinalName>
    <plugins>
        <plugin>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-maven-pluginartifactId>
        plugin>
    plugins>
build>
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第三步: 配置order-service工程的application.yml文件

server:
  port: 8080
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/cloud_order?useSSL=false
    username: root
    password: 123
    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
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第四步: 创建Mapper接口和自定义Service类,这里就不再创建业务类的实现类了

@Mapper
public interface OrderMapper {
    @Select("select * from tb_order where id = #{id}")
    Order findById(Long id);
}
@Service
public class OrderService {
    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private UserClient userClient;
    public Order queryOrderById(Long orderId) {
        // 查询订单
        Order order = orderMapper.findById(orderId);
        // 返回查询到的订单对象,user属性为null
        return order;
    }
}
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第五步: 在order-service工程中创建controller/OrderController,编写接口根据订单Id从订单数据库中查询订单信息

@RestController
@RequestMapping("order")
public class OrderController {
   @Autowired
   private OrderService orderService;
    @GetMapping("{orderId}")
    public Order queryOrderByUserId(@PathVariable("orderId") Long orderId) {
        // 根据id查询订单并返回
        return orderService.queryOrderById(orderId);
    }
}
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第五步: 打开浏览器访问http://localhost:8080/order/101可以查询到订单数据的但此时user属性的值是null

{
	"id": 101,
	"price": 699900,
	"name": "Apple 苹果 iPhone 12 ",
	"num": 1,
	"userId": 1,
	"user": null
}
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创建用户微服务模块(工程)

第一步: 执行cloud-user.sql文件创建用户数据库,创建tb_user表及其对应的实体类

@Data
public class User {
    private Long id;
    private String username;
    private String address;
}
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第二步: 配置user-service工程的pom.xml文件

<parent>
    <artifactId>cloud-demoartifactId>
    <groupId>cn.itcast.demogroupId>
    <version>1.0version>
parent>
<modelVersion>4.0.0modelVersion>

<artifactId>user-serviceartifactId>

<dependencies>
    <dependency>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-webartifactId>
    dependency>
    <dependency>
        <groupId>mysqlgroupId>
        <artifactId>mysql-connector-javaartifactId>
    dependency>
    
    <dependency>
        <groupId>org.mybatis.spring.bootgroupId>
        <artifactId>mybatis-spring-boot-starterartifactId>
    dependency>
dependencies>
<build>
    <finalName>appfinalName>
    <plugins>
        <plugin>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-maven-pluginartifactId>
        plugin>
    plugins>
build>
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第三步: 配置user-service工程的application.yml文件

server:
  port: 8081
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/cloud_user?useSSL=false
    username: root
    password: 123
    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
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第四步: 配置Mapper接口和Service类,这里就不再创建业务类的实现类了

@Mapper
public interface UserMapper {    
    @Select("select * from tb_user where id = #{id}")
    User findById(@Param("id") Long id);
}
@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;
    public User queryById(Long id) {
        return userMapper.findById(id);
    }
}
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第五步: 在user-service工程中创建controller/UserController,编写接口根据用户Id从用户数据库中查询用户信息

@Slf4j
@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;
    /**
     * 路径： /user/110
     * @param id 用户id
     * @return 用户
     */
    @GetMapping("/{id}")
    public User queryById(@PathVariable("id") Long id) {
        return userService.queryById(id);
    }
}
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第六步: 打开浏览器访问http://localhost:8081/user/1查询到的数据如下

{
	"id": 1,
	"username": "柳岩",
	"address": "湖南省衡阳市"
}
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远程调用(RestTemplate)

需求: 访问订单模块根据订单Id查询订单,根据查询的订单对象中包含的userId访问用户模块查询出用户信息,然后封装到订单对象的user属性中返回

RestTemplate是Spring提供的发起http请求的工具类

第一步: 在order-service服务的代码逻辑中向user-service服务发起一个http请求,访问http://localhost:8081/user/{userId}查询用户信息

第二步: 在order-service服务中的OrderApplication启动类中(本质是个配置类)中注册RestTemplate实例到Spring容器当中

@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
public class OrderApplication {
    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }

    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}
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第三步: 修改订单服务的OrderService类中的queryOrderById方法,根据Order对象中包含的userId发http请求访问用户服务查询用户信息,然后一并返回

@Service
public class OrderService {
    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private RestTemplate restTemplate;

    public Order queryOrderById(Long orderId) {
        // 1.查询订单
        Order order = orderMapper.findById(orderId);
        // 2.使用RestTemplate指定url地址发起http请求查询User,指定接收的类型(服务器默认返回Json类型的数据)
        String url = "http://localhost:8081/user/" + order.getUserId();
        User user = restTemplate.getForObject(url, User.class);
        // 3.存入order
        order.setUser(user);
        // 4.返回
        return order;
    }
}
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第四步: 访问订单服务查询订单的接口http://localhost:8080/order/101,此时订单对象中包含对应用户的信息

{
	"id": 101,
	"price": 699900,
	"name": "Apple 苹果 iPhone 12 ",
	"num": 1,
	"userId": 1,
	"user": {
		"id": 1,
		"username": "柳岩",
		"address": "湖南省衡阳市"
	}
}
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