初识

由于是开篇，先撇开springcloud的各种核心组件，来个demo 简单的认知下。话不多说直接开撸。

场景

简单场景如下图

sc1-1

编写服务提供者

microservice-simple-provider-user

引入pom依赖文件如下：

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.kirago.sc</groupId>
    <artifactId>microservice-simple-provider-user</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>microservice-simple-provider-user</name>
    <description>microservice-simple-provider-user project for Spring Boot</description>

    <properties>
        <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>mysql</groupId>-->
            <!--<artifactId>mysql-connector-java</artifactId>-->
            <!--<scope>runtime</scope>-->
        <!--</dependency>-->

        <!-- https://mvnrepository.com/artifact/com.h2database/h2 -->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <version>1.4.197</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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>

数据库访问采用内嵌数据库H2来做 demo 的持久化结合JPA来搞。

服务提供者的yaml文件配置如下：

server:
  port: 8000
spring:
  jpa:
    generate-ddl: false
    show-sql: true
    hibernate:
      ddl-auto: update

  datasource:
    platform: h2
    schema: classpath:sql/schema.sql #数据scchema sql
    data: classpath:sql/data.sql #数据初始化sql
    url: jdbc:h2:mem:dbtest
    username: root
    password: root
    driver-class-name: org.h2.Driver
  h2:
    console:
      settings:
        web-allow-others: true #开启web页面端
      path: /h2 #uri路径
      enabled: true #开启远端访问
logging:
  level:
    root: INFO
    org.hibernate: INFO
    org.hibernate.type.descriptor.sql.BasicBinder: TRACE
    org.hibernate.type.descriptor.sql.BasicExtractor: TRACE

schema sql 如下：

drop table user if exists;
create table user (
    id bigint generated by default as identity,
    username varchar(48),
    name varchar(20),
    age int(3),
    balance decimal(10,2),
    primary key (id));

data.sql如下：

1
2
3

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', 21, 101.00);
insert into user (id, username, name, age, balance) values (3, 'account3', '王五', 22, 111.00);

登录H2内存服务器结果显示如下：

controller层如下：

package com.kirago.sc.microservicesimpleprovideruser.controller;

import com.kirago.sc.microservicesimpleprovideruser.entity.User;
import com.kirago.sc.microservicesimpleprovideruser.repository.UserRepository;
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 java.util.Optional;

@RestController
public class UserController {

    @Autowired
    private UserRepository userRepository;

    @GetMapping("/{id}")
    public User findById(@PathVariable Long id){

        Optional<User> user = userRepository.findById(id);
        return user.get();

    }
}

实体类如下:

package com.kirago.sc.microservicesimpleprovideruser.entity;

import lombok.Data;

import javax.persistence.*;
import java.math.BigDecimal;

@Entity
@Data
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;
}

Dao层：

package com.kirago.sc.microservicesimpleprovideruser.repository;

import com.kirago.sc.microservicesimpleprovideruser.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
}

通过postman 发送请求测试验证如下：
服务消费者
microservice-simple-consumer-movie
由于此部分内容比较简单就是构建好消费者需要获取的用户，直接构建了一个POJO，然后通过RestTemplate去请求服务提供者。

重点注意的就是 controller 层中的用法而已，如下：

package com.kirago.sc.microservicesimpleconsumermovie.controller;

import com.kirago.sc.microservicesimpleconsumermovie.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
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 {

    @Value("${user.userServiceUrl}")
    private String userServiceUrl;

    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/user/{id}")
    public User findById(@PathVariable Long id){
        return restTemplate.getForObject(userServiceUrl + id, User.class);
    }
}

此 demo 为了避免 userServiceUrl 的硬编码，通过 @Value 注解获取 yaml 配置文件的环境变量实现。

消费者 yaml 配置如下：

user:
  userServiceUrl: http://localhost:8000/

server:
  port: 8001

通过 postman 发送请求验证如下：

示例代码链接

初识

场景

编写服务提供者

microservice-simple-provider-user

服务消费者

microservice-simple-consumer-movie