微服务的初步使用

环境说明

jdk1.8

maven3.6.3

mysql8

idea2022

spring cloud2022.0.8

微服务案例的搭建

新建父工程

打开IDEA，File->New ->Project，填写Name（工程名称）和Location（工程存储位置），选择Java语言和Maven，点击Create创建maven工程，该工程为所有工程的父工程

官方查看Spring Cloud与Spring Boot的版本匹配问题

Spring Cloud

Spring Boot2.7.x匹配的Spring Cloud的版本为2021.0.x

修改pom.xml

<?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>org.example</groupId><artifactId>spring-cloud-bk-2023</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.12</version></parent><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-logging</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.4</version><scope>provided</scope></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>2021.0.8</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><repositories><repository><id>spring-snapshots</id><name>Spring Snapshots</name><url>http://repo.spring.io/libs-snapshot-local</url><snapshots><enabled>true</enabled></snapshots></repository><repository><id>spring-milestones</id><name>Spring Milestones</name><url>http://repo.spring.io/libs-milestone-local</url><snapshots><enabled>false</enabled></snapshots></repository><repository><id>spring-releases</id><name>Spring Releases</name><url>http://repo.spring.io/libs-release-local</url><snapshots><enabled>false</enabled></snapshots></repository></repositories><pluginRepositories><pluginRepository><id>spring-snapshots</id><name>Spring Snapshots</name><url>http://repo.spring.io/libs-snapshot-local</url><snapshots><enabled>true</enabled></snapshots></pluginRepository><pluginRepository><id>spring-milestones</id><name>Spring Milestones</name><url>http://repo.spring.io/libs-milestone-local</url><snapshots><enabled>false</enabled></snapshots></pluginRepository></pluginRepositories><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

• 父工程引入公共的依赖，例如：所有微服务模块均需要用到spring boot，spring boot依赖版本为2.7.12
• 同时声明spring cloud的依赖。spring cloud依赖版本为2021.0.8，声明依赖后，以后子工程就不需要再指定spring cloud的相关版本了。
• dependencies标签配置远程仓库地址

注意：添加依赖后，需要刷新依赖。

微服务模块

父工程创建好之后，接下来就搭建各个微服务模块，这里以product-service(商品服务)和order-service(订单服务)为例。实现用户下订单的功能。

用户下订单业务流程如下：用户通过浏览器下订单，浏览器发起请求到订单服务，订单服务通过调用商品服务得到商品信息。

product-service（商品服务）

创建子工程

创建product-service子模块，右键父工程->New->Module

填写模块名称：product-service，选择Java，Maven，点击创建，如下图：

添加依赖

修改product-service的pom.xml，在</project>的上方添加如下依赖

    <dependencies><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.33</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency></dependencies>

刷新依赖

商品模块业务开发

代码结构如下

实体类

package org.example.product.entity;import lombok.Data;import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import java.math.BigDecimal;/*** 商品实体类*/
@Data
@Entity
@Table(name="tb_product")
public class Product {@Idprivate Long id;private String productName;private Integer status;private BigDecimal price;private String productDesc;private String caption;private Integer inventory;
}

Dao接口

package org.example.product.dao;import org.example.product.entity.Product;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;public interface ProductDao extends JpaRepository<Product, Long>, JpaSpecificationExecutor<Product> {}

Service接口

package org.example.product.service;import org.example.product.entity.Product;public interface ProductService {/*** 根据id查询*/Product findById(Long id);/*** 保存*/void save(Product product);/*** 更新*/void update(Product product);/*** 删除*/void delete(Long id);
}

Service接口实现类

package org.example.product.service.impl;import org.example.product.dao.ProductDao;
import org.example.product.entity.Product;
import org.example.product.service.ProductService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class ProductServiceImpl implements ProductService {@Autowiredprivate ProductDao productDao;@Overridepublic Product findById(Long id) {return productDao.findById(id).get();}@Overridepublic void save(Product product) {productDao.save(product);}@Overridepublic void update(Product product) {productDao.save(product);}@Overridepublic void delete(Long id) {productDao.deleteById(id);}
}

Controller类

package org.example.product.controller;import org.example.product.entity.Product;
import org.example.product.service.ProductService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;@RestController
@RequestMapping("/product")
public class ProductController {@Autowiredprivate ProductService productService;@Value("${server.port}")private String port;@Value("${client.ip-address}")private String ip;@RequestMapping(value = "/{id}",method = RequestMethod.GET)public Product findById(@PathVariable Long id) {Product product = productService.findById(id);product.setProductName("访问的服务地址:"+ip + ":" + port);return product;}@RequestMapping(value = "",method = RequestMethod.POST)public String save(@RequestBody Product product) {productService.save(product);return "保存成功";}}

启动类

package org.example.product;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;@SpringBootApplication
@EntityScan("org.example.product.entity")
public class ProductApplication {public static void main(String[] args) {SpringApplication.run(ProductApplication.class, args);}
}

application.yml配置

server:port: 9001
spring:application:name: service-productdatasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/shop1?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8username: rootpassword: 123jpa:database: MySQLshow-sql: trueopen-in-view: truegenerate-ddl: true #自动创建表client:ip-address: 10.111.50.229

注意修改数据库信息，例如url、username、password

创建业务数据库

使用mysql创建数据库：shop1

create database shop1;

测试

运行启动类：ProductApplication.java

因为application.yml的spring.jpa.generate-ddl 配置为true会自动创建表，启动成功后，刷新数据库能看到tb_product表，表还没有具体数据

手动为tb_product表添加两行测试数据，例如：

浏览器访问

http://localhost:9001/product/1

访问到了数据库的数据 

order-service（订单服务）

创建子工程

子模块：order-service

添加依赖

修改order-service的pom.xml，在</project>的上方添加如下依赖

	<dependencies><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.33</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency></dependencies>

刷新依赖

订单模块业务开发

代码结构如下：

实体类

package org.example.order.entity;import lombok.Data;import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import java.math.BigDecimal;/*** 商品实体类*/
@Data
@Entity
@Table(name="tb_product")
public class Product {@Idprivate Long id;private String productName;private Integer status;private BigDecimal price;private String productDesc;private String caption;private Integer inventory;
}

 控制类

package org.example.order.controller;import org.example.order.entity.Product;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;@RestController
@RequestMapping("/order")
public class OrderController {@Autowiredprivate RestTemplate restTemplate;@RequestMapping(value = "/buy/{id}", method = RequestMethod.GET)public Product findById(@PathVariable Long id){Product product = null;//调用其他微服务，get请求用getXxx post请求用postXxxproduct  = restTemplate.getForObject("http://localhost:9001/product/1", Product.class);return product;}}

  启动类

package org.example.order;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;@SpringBootApplication
@EntityScan("org.example.order.entity")
public class OrderApplication {/*** 使用spring提供的RestTemplate发送http请求到商品服务*      1.创建RestTemplate对象交给容器管理*      2.在使用的时候,调用其方法完成操作 (getXX,postxxx)*/@Beanpublic RestTemplate restTemplate(){return new RestTemplate();}public static void main(String[] args) {SpringApplication.run(OrderApplication.class,args);}
}

  application.yml配置

server:port: 9002
spring:application:name: service-orderdatasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3306/shop1?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8username: rootpassword: 123jpa:database: MySQLshow-sql: trueopen-in-view: truegenerate-ddl: true #自动创建表client:ip-address: 10.111.50.229

注意修改数据库信息。

测试

运行启动类：OrderApplication.java

浏览器访问

http://localhost:9002/order/buy/1

 效果如下

和之前直接访问product服务返回一致，说明order服务调用了product服务

http://localhost:9001/product/1

代码总结：

1. 在order启动类，创建RestTemplate对象交给Spring容器管理
2. 在order控制类，注入restTemplate对象，在具体方法里调用商品服务：restTemplate.getForObject("http://localhost:9001/product/1", Product.class);

注册中心的使用

搭建注册中心

把服务注册到注册中心

用服务列表名称进行调用

Eureka的高可用

完成！enjoy it!