从本文开始,以一个电影售票系统为例讲解Spring Cloud
1. 版本
jdk:1.8
SpringBoot:2.0.0.RELEASE
SpringCloud:Finchley.M8
2. 系统信息
使用Spring Data JPA作为持久层框架,使用H2作为数据库
3. 编写服务提供者
开发:
> 创建一个Spring Boot项目。pom.xml内容如下:
4.0.0 com.itmuch.cloud microservice-simple-provider-user 0.0.1-SNAPSHOT jar org.springframework.boot spring-boot-starter-parent 2.0.0.RELEASE UTF-8 UTF-8 1.8 org.springframework.boot spring-boot-starter-data-jpa org.springframework.boot spring-boot-starter-web com.h2database h2 org.springframework.boot spring-boot-starter-actuator org.springframework.boot spring-boot-starter-test test org.springframework.boot spring-boot-maven-plugin
其中,spring-boot-starter-web提供了SpringMVC支持;spring-boot-starter-data-jpa提供了Spring Data JPA的支持。
> 准备好建表语句,在项目的resources目录下创建sql文件夹,在sql文件夹下建立schema.sql,并添加如下内容:
DROP TABLE user if EXISTS;CREATE TABLE user ( id bigint generated BY DEFAULT AS IDENTITY, username VARCHAR(40), name VARCHAR(20), age INT(3), balance DECIMAL(10, 2), PRIMARY KEY (id));
> 准备几条数据,在sql文件夹下创建data.sql,并添加如下内容:
INSERT INTO user (id, username, name, age, balance) VALUES (1, 'account1', '张三', 20, 100.00);INSERT INTO user (id, username, name, age, balance) VALUES (2, 'account2', '李四', 28, 180.00);INSERT INTO user (id, username, name, age, balance) VALUES (3, 'account3', '王五', 32, 280.00);
> 创建用户实体类
package com.itmuch.cloud.microservicesimpleprovideruser.pojo;import javax.persistence.*;import java.math.BigDecimal;@Entitypublic class User { @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @Column private String username; @Column private String name; @Column private Integer age; @Column private BigDecimal balance; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public BigDecimal getBalance() { return balance; } public void setBalance(BigDecimal balance) { this.balance = balance; }}
> 创建DAO
package com.itmuch.cloud.microservicesimpleprovideruser.dao;import com.itmuch.cloud.microservicesimpleprovideruser.pojo.User;import org.springframework.data.jpa.repository.JpaRepository;import org.springframework.stereotype.Repository;@Repositorypublic interface UserRepository extends JpaRepository{}
> 创建Controller
package com.itmuch.cloud.microservicesimpleprovideruser.controller;import com.itmuch.cloud.microservicesimpleprovideruser.dao.UserRepository;import com.itmuch.cloud.microservicesimpleprovideruser.pojo.User;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.RestController;@RestControllerpublic class UserController { @Autowired private UserRepository userRepository; @GetMapping("/{id}") public User findById(@PathVariable Long id) { User findOne = userRepository.findById(id).get(); return findOne; }}
> 编写配置文件。将application.properties重命名为application.yml。
server: port: 8000spring: jpa: generate-ddl: false show-sql: true hibernate: ddl-auto: none datasource: # 指定数据源 platform: h2 # 指定数据源类型 url: jdbc:h2:mem:cloud # 指定h2数据库的连接地址 driver-class-name: org.h2.Driver # 指定h2数据库的驱动 username: root # 指定h2数据库的登录用户 password: 20121221 # 指定h2数据库的登录密码 schema: classpath:/sql/schema.sql # 指定h2数据库的建表脚本 data: classpath:/sql/data.sql # 指定h2数据库的数据脚本 h2: console: path: /h2-console enabled: truelogging: level: org.hibernate: info org.hibernate.type.descriptor.sql.BasicBinder: TRACE org.hibernate.type.descriptor.sql.BasicExtractor: TRACEinfo: app: name: microservice-simple-provider-user encoding: UTF-8 java: source: 1.8 target: 1.8
测试:
在开发中整合了actuator模块,Spring Boot Actuator提供了很多监控端点。
具体可查看:
> Spring Boot Actuator测试
启动Spring Boot项目,访问:,若如下图,则正常
(默认只展示状态,详细信息不展示。若想查看详细信息,可点击上方URL查看)
> 项目测试
启动Spring Boot项目,访问:,若如下图,则正常
4. 编写服务消费者
开发:
> 创建一个Spring Boot项目。pom.xml内容如下:
4.0.0 com.itmuch.cloud microservice-simple-consumer-movie 0.0.1-SNAPSHOT jar org.springframework.boot spring-boot-starter-parent 2.0.0.RELEASE UTF-8 UTF-8 1.8 org.springframework.boot spring-boot-starter-web org.springframework.boot spring-boot-starter-actuator org.springframework.boot spring-boot-starter-test test org.springframework.boot spring-boot-maven-plugin
> 创建一个用户实体类
package com.itmuch.cloud.microservicesimpleconsumermovie.pojo;import java.math.BigDecimal;public class User { private Long id; private String username; private String name; private Integer age; private BigDecimal balance; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public BigDecimal getBalance() { return balance; } public void setBalance(BigDecimal balance) { this.balance = balance; }}
> 修改启动类
package com.itmuch.cloud.microservicesimpleconsumermovie;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.context.annotation.Bean;import org.springframework.web.client.RestTemplate;@SpringBootApplicationpublic class MicroserviceSimpleConsumerMovieApplication { public static void main(String[] args) { SpringApplication.run(MicroserviceSimpleConsumerMovieApplication.class, args); } @Bean public RestTemplate restTemplate() { return new RestTemplate(); }}
> 创建Controller,在其中使用RestTemplate请求用户微服务的API。
package com.itmuch.cloud.microservicesimpleconsumermovie.controller;import com.itmuch.cloud.microservicesimpleconsumermovie.pojo.User;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.RestController;import org.springframework.web.client.RestTemplate;@RestControllerpublic class MovieController { @Autowired private RestTemplate restTemplate; @GetMapping("/user/{id}") public User findById(@PathVariable Long id) { return this.restTemplate.getForObject("http://localhost:8000/" + id, User.class); }}
> 编写配置文件。将application.properties重命名为application.yml。
server: port: 8010info: app: name: microservice-simple-consumer-movie encoding: UTF-8 java: source: 1.8 target: 1.8
测试:
在开发中同样整合了actuator模块
具体可查看:
> Spring Boot Actuator测试
启动Spring Boot项目,访问:,若如下图,则正常
> 项目测试
启动Spring Boot项目,访问:,若如下图,则正常
5. 总结
在传统的应用程序中,一般都是这样做的。然而,这种方式存在问题。
1. 适用场景有限:如果服务提供者的网络地址(IP和端口)发生了变化,将会影响服务消费者。
2. 无法动弹伸缩:在生成环境中,每个微服务一般都会部署多个实例,从而实现容灾和负载均衡。在微服务架构的系统中,还需要系统具备自动伸缩的能力,例如动态增加节点等。硬编码无法适应这种需求。
将会在下一篇博客中,解决这些问题。敬请期待~~~
6. 参考
周立 --- 《Spring Cloud与Docker微服务架构与实战》