SpringCloud系列二:硬编码实现简单的服务提供者与服务消费者
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:
<?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>com.itmuch.cloud</groupId>
<artifactId>microservice-simple-provider-user</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.0.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
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;
@Entity
public 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;
@Repository
public interface UserRepository extends JpaRepository<User, Long> {
}
> 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;
@RestController
public 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: 8000
spring:
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: true
logging:
level:
org.hibernate: info
org.hibernate.type.descriptor.sql.BasicBinder: TRACE
org.hibernate.type.descriptor.sql.BasicExtractor: TRACE
info:
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:http://www.cnblogs.com/jinjiyese153/p/8607895.html
> Spring Boot Actuator测试
启动Spring Boot项目,访问:http://localhost:8000/actuator/health,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:http://localhost:8000/1,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:
<?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>com.itmuch.cloud</groupId>
<artifactId>microservice-simple-consumer-movie</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.0.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
> 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;
@SpringBootApplication
public 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;
@RestController
public 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: 8010
info:
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:http://www.cnblogs.com/jinjiyese153/p/8607895.html
> Spring Boot Actuator测试
启动Spring Boot项目,访问:http://localhost:8010/actuator/health,若如下图,则正常
> 项目测试
启动Spring Boot项目,访问:http://localhost:8010/user/1,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》