SpringCloud微服务【实用篇】

编程入门行业动态更新时间:2024-10-28 13:20:32

SpringCloud微服务【实用篇】

一：服务拆分及远程调用

1. 服务拆分

2. 服务间调用

3. 提供者和消费者

一：服务拆分及远程调用

1. 服务拆分

服务拆分注意事项

1. 单一职责：不同微服务，不要重复开发相同业务；

2. 数据独立：不要访问其它微服务的数据库；

3. 面向服务：将自己的业务暴露为接口，供其它微服务调用；

案例：父工程cloud-demo，子工程order-service根据id查询订单，user-service根据id查询用户表

第一步：准备数据库表---数据库分离

cloud_user数据库的tb_user表

cloud_order数据库的tb_order表

第二步：父项目cloud-demo---项目分离

主要使用pom.xml指定一些版本号

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns=".0.0"xmlns:xsi=""xsi:schemaLocation=".0.0 .0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>cn.itcast.demo</groupId><artifactId>cloud-demo</artifactId><version>1.0</version><modules><module>user-service</module><module>order-service</module></modules><packaging>pom</packaging><!--SpringBoot项目--><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><!--版本号--><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></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></dependencies></dependencyManagement><dependencies><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></dependency></dependencies>
</project>

第三步：子工程order-service

项目结构目录：

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns=".0.0"xmlns:xsi=""xsi:schemaLocation=".0.0 .0.0.xsd"><parent><artifactId>cloud-demo</artifactId><groupId>cn.itcast.demo</groupId><version>1.0</version></parent><modelVersion>4.0.0</modelVersion><artifactId>order-service</artifactId><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></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build>
</project>

PoJo类Order

package cn.itcast.order.pojo;import lombok.Data;@Data
public class Order {private Long id;private Long price;private String name;private Integer num;private Long userId;private User user;
}

Pojo类User

package cn.itcast.order.pojo;import lombok.Data;@Data
public class User {private Long id;private String username;private String address;
}

mapper接口

package cn.itcast.order.mapper;import cn.itcast.order.pojo.Order;
import org.apache.ibatis.annotations.Select;public interface OrderMapper {@Select("select * from tb_order where id = #{id}")Order findById(Long id);
}

Service调用mapper接口

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;@Service
public class OrderService {@Autowiredprivate OrderMapper orderMapper;public Order queryOrderById(Long orderId) {// 1.查询订单Order order = orderMapper.findById(orderId);// 4.返回return order;}
}

Controller调用Service

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;@RestController
@RequestMapping("/order")
public class OrderController {@Autowiredprivate OrderService orderService;@GetMapping("/{orderId}")// @RequestMapping("/order")  和@GetMapping("/{orderId}")等价于@GetMapping("/user/{orderId})public Order queryOrderByUserId(@PathVariable("orderId") Long orderId) {// 根据id查询订单并返回return orderService.queryOrderById(orderId);}
}

application.yml配置

server:port: 8080
spring:datasource:url: jdbc:mysql://localhost:3306/cloud_order?useSSL=falseusername: rootpassword: 123456driver-class-name: com.mysql.jdbc.Driver
mybatis:type-aliases-package: cn.itcast.user.pojoconfiguration:map-underscore-to-camel-case: true
logging:level:cn.itcast: debugpattern:dateformat: MM-dd HH:mm:ss:SSS

第四步：子工程user-service

项目结构目录：

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns=".0.0"xmlns:xsi=""xsi:schemaLocation=".0.0 .0.0.xsd"><parent><artifactId>cloud-demo</artifactId><groupId>cn.itcast.demo</groupId><version>1.0</version></parent><modelVersion>4.0.0</modelVersion><artifactId>user-service</artifactId><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></dependencies><build><finalName>app</finalName><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build>
</project>

Pojo类User

package cn.itcast.order.pojo;import lombok.Data;@Data
public class User {private Long id;private String username;private String address;
}

mapper接口

package cn.itcast.user.mapper;import cn.itcast.user.pojo.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;public interface UserMapper {@Select("select * from tb_user where id = #{id}")User findById(@Param("id") Long id);
}

Service调用mapper接口

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;@Service
public class UserService {@Autowiredprivate UserMapper userMapper;public User queryById(Long id) {return userMapper.findById(id);}
}

Controller调用Service

package cn.itcast.user.web;import cn.itcast.user.pojo.User;
import cn.itcast.user.service.UserService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;@Slf4j
@RestController
@RequestMapping("/user")
public class UserController {@Autowiredprivate 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);}
}

application.yml配置

server:port: 8081
spring:datasource:url: jdbc:mysql://localhost:3306/cloud_user?useSSL=falseusername: rootpassword: 123456driver-class-name: com.mysql.jdbc.Driver
mybatis:type-aliases-package: cn.itcast.user.pojoconfiguration:map-underscore-to-camel-case: true
logging:level:cn.itcast: debugpattern:dateformat: MM-dd HH:mm:ss:SSS

启动这两个服务器（两个项目的启动类都需要加上@MapperScan注解）

Order单独进行访问，User信息为null

User单独进行访问

2. 服务间调用

前面项目已经部署好，单独的根据id查订单信息Order，查用户信息User都可以查到！但是现在客户要求查询订单需求的同时把用户信息也查出来！

需求：根据订单id查询订单的同时，把订单所属的用户信息一起返回

分析：订单模块只能查到订单信息，用户模块只能查出用户信息；但是现在用户要求的是订单信息查询的同时把用户信息查出来

所以不得不去修改订单模块的功能，要求在查询出，订单信息的同时，还可以通过订单信息里面的userId查询相互用户信息。

思考：直接使用订单模块去查用户模块的数据行不行？显然不可以，前面已经分析了不要重复的开发业务；只能从订单向用户发起远程调用！

解决：

①实际上用户信息对外面暴露了一个链接地址@GetMapping("/user/{id})，通过这个链接地址就能访问数据库拿到用户信息给浏览器。

②那么此时的订单模块如果能发出http协议的链接请求，也能返回用户信息数据然后与原来的订单信息数据结合就能完成需求。

所以现在核心问题：如何在订单信息模块的Java代码中发Http请求！

Spring提供了一个RestTemplate类工具可以完成！具体实现步骤如下：

第一步：注册RestTemplate

在启动类OrderApplication中注入RestTemplate类！

package cn.itcast.order;import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
public class OrderApplication {public static void main(String[] args) {SpringApplication.run(OrderApplication.class, args);}// 注册RestTemplate@Beanpublic RestTemplate restTemplate(){return new RestTemplate();}}

第二步：服务远程调用RestTemplate

通过这个RestTemplate这个类去调用getForObject()方法：第一个参数是URL地址，第二个参数是要返回的类型。

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;@Service
public class OrderService {@Autowiredprivate OrderMapper orderMapper;// 注入RestTemplate@Autowiredprivate RestTemplate restTemplate;public Order queryOrderById(Long orderId) {// 1.查询订单Order order = orderMapper.findById(orderId);// 2.发出请求查询用户信息String url = "http://localhost:8081/user/"+order.getUserId();User user = restTemplate.getForObject(url, User.class);// 3. 把用户信息封装到orderorder.setUser(user);// 4.返回return order;}
}

此时Order单独进行访问，User信息就能显示出来

总结微服务调用方式