1.创建父工程
2.创建子模块
- 2.1 服务提供方user-service
- 2.2 服务消费端consumer-demo
3.总结

1.创建父工程

工程信息:
<groupId>com.keyi.demo</groupId>
        <artifactId>cloud-demo</artifactId>
<version>1.0-SNAPSHOT</version>

具体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>com.keyi.demo</groupId>
    <artifactId>cloud-demo</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <modules>
        <module>user-service</module>
        <module>consumer-demo</module>
    </modules>
    <packaging>pom</packaging>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
        <relativePath/>
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR1</spring-cloud.version>
        <mapper.starter.version>2.0.3</mapper.starter.version>
        <mysql.version>5.1.32</mysql.version>
    </properties>
    <dependencyManagement>
        <dependencies>
        <!-- springCloud依赖管理 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        <!-- 通用Mapper启动器 -->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>${mapper.starter.version}</version>
        </dependency>
        <!-- mysql驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2.创建子模块

2.1 服务提供方user-service

具体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">
    <parent>
        <artifactId>cloud-demo</artifactId>
        <groupId>com.keyi.demo</groupId>
        <version>1.0.0-SNAPSHOT</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>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
        </dependency>
    </dependencies>
</project>

yml

server:
  port: 8081
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/clouddb01
    username: root
    password: 123456
    hikari:
      maximum-pool-size: 20
      minimum-idle: 10
mybatis:
  type-aliases-package: com.keyi.user.pojo

类

// 实体类
@Table(name = "tb_user")
@Data
public class User implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String userName; // 用户名
    private String password; // 密码
    private String name; // 姓名
    private Integer age; // 年龄
    private Integer sex; // 性别，1男性，2女性
    private Date birthday; // 出生日期
    private Date created; // 创建时间
    private Date updated; // 更新时间
    private String note; // 备注
}
// mapper
public interface UserMapper extends Mapper<User> {}
// service
@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;
    public User queryById(Long id) {
        return this.userMapper.selectByPrimaryKey(id);
    }
}
// controller
@RestController
@RequestMapping("user")
public class UserController {
    @Autowired
    private UserService userService;
    @GetMapping("/{id}")
    public User queryById(@PathVariable("id") Long id) {
        return this.userService.queryById(id);
    }
}
// 启动器
@SpringBootApplication
@MapperScan("com.keyi.user.mapper")
public class UserApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserApplication.class, args);
    }
}

启动效果
01 微服务场景模拟入门 - 图1

2.2 服务消费端consumer-demo

<?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">
    <parent>
        <artifactId>cloud-demo</artifactId>
        <groupId>com.keyi.demo</groupId>
        <version>1.0.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>consumer-demo</artifactId>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
</project>

@Data
public class User {
    private Long id;
    private String userName; // 用户名
    private String password; // 密码
    private String name; // 姓名
    private Integer age; // 年龄
    private Integer sex; // 性别，1男性，2女性
    private Date birthday; // 出生日期
    private Date created; // 创建时间
    private Date updated; // 更新时间
    private String note; // 备注
}
@RestController
@RequestMapping("consumer")
public class ConsumerController {
    @Autowired
    private RestTemplate restTemplate;
    @GetMapping("{id}")
    public User queryById(@PathVariable("id") Long id) {
        String url = "http://localhost:8081/user/" + id;
        return this.restTemplate.getForObject(url, User.class);
    }
}
@SpringBootApplication
public class ConsumerApplication {
    @Bean
    public RestTemplate restTemplate() {
        // 这次我们使用了OkHttp客户端,只需要注入工厂即可
        return new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class, args);
    }
}

启动
01 微服务场景模拟入门 - 图2

3.总结

user-service: 一个提供根据id查询用户的微服务
consumer-demo: 一个服务调用者，通过RestTemplate远程调用user-service
大致流程:
01 微服务场景模拟入门 - 图3
存在问题:
● 在consumer中，我们把url地址硬编码到了代码中，不方便后期维护
● consumer需要记忆user-service的地址，如果出现变更，可能得不到通知，地址将失效
● consumer不清楚user-service的状态，服务宕机也不知道
● user-service只有1台服务，不具备高可用性
● 即便user-service形成集群，consumer还需自己实现负载均衡
上面所述问题，也就是分布式服务必然要面临的问题：
● 服务管理

如何自动注册和发现
如何实现状态监管
如何实现动态路由

● 服务如何实现负载均衡
● 服务如何解决容灾问题
● 服务如何实现统一配置