首先,我们需要模拟一个服务调用的场景。方便后面学习微服务架构
建表:
CREATE DATABASE IF NOT EXISTS springcloud CHARACTER SET utf8;
USE springcloud;
CREATE TABLE `tb_user` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`user_name` varchar(32) DEFAULT NULL,
`password` varchar(32) DEFAULT NULL,
`name` varchar(32) DEFAULT NULL,
`age` int(11) DEFAULT NULL,
`sex` int(11) DEFAULT NULL,
`birthday` date DEFAULT NULL,
`created` date DEFAULT NULL,
`updated` date DEFAULT NULL,
`note` varchar(32) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO tb_user VALUES(null,"yang1","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang2","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang3","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang4","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang5","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang6","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang7","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang8","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang9","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang10","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang11","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang12","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang13","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang14","1234561","y1",11,1,20180828,20190101,20190101,"1");
INSERT INTO tb_user VALUES(null,"yang15","1234561","y1",11,1,20180828,20190101,20190101,"1");
1、创建父工程(聚合工程)
创建 maven 工程:
填写项目信息:
修改 pom:
<?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>cn.ys.demo</groupId>
<artifactId>cloud-demo</artifactId>
<version>1.0.0-SNAPSHOT</version>
<modules>
<module>user-service</module>
</modules>
<packaging>pom</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.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>
<spring-cloud.version>Finchley.SR1</spring-cloud.version>
<mybatis.starter.version>1.3.2</mybatis.starter.version>
<mapper.starter.version>2.0.2</mapper.starter.version>
<mysql.version>5.1.32</mysql.version>
<pageHelper.starter.version>1.2.3</pageHelper.starter.version>
</properties>
<dependencyManagement>
<dependencies>
<!-- springCloud -->
<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>
删除 src
目录
2、服务提供者
我们新建一个项目,对外提供查询用户的服务。
选中 父工程:
添加依赖:
<?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>cn.ys.demo</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<groupId>cn.ys.demo</groupId>
<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>
</dependency>
<dependency>
<groupId>tk.mybatis</groupId>
<artifactId>mapper-spring-boot-starter</artifactId>
</dependency>
</dependencies>
</project>
新建配置文件:application.yml
server:
port: 8081
spring:
application:
name: user-service
datasource:
url: jdbc:mysql://yangnanxi.cn:3306/springcloud
username: yang
password: 123456
hikari:
maximum-pool-size: 30
minimum-idle: 10
新建启动类:UserServiceApplication
package cn.ys.user;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import tk.mybatis.spring.annotation.MapperScan;
@SpringBootApplication
@MapperScan("cn.ys.user.mapper")
public class UserServiceApplication {
public static void main(String[] args) {
SpringApplication.run(UserServiceApplication.class,args);
}
}
编写实体类:User
package cn.ys.user.pojo;
import lombok.Data;
import tk.mybatis.mapper.annotation.KeySql;
import javax.persistence.Id;
import javax.persistence.Table;
import java.util.Date;
@Table(name = "tb_user")
@Data
public class User {
@Id
@KeySql(useGeneratedKeys = true)
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; // 创建日期
private Date updated; // 更新日期
private String note; // 备注
}
IDEA 安装 lombok 插件:
编写 mapper :UserMapper
package cn.ys.user.mapper;
import cn.ys.user.pojo.User;
import tk.mybatis.mapper.common.Mapper;
public interface UserMapper extends Mapper<User> {
}
编写 service :UserService
package cn.ys.user.service;
import cn.ys.user.mapper.UserMapper;
import cn.ys.user.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class UserService {
@Autowired
private UserMapper userMapper;
public User queryById(Long id){
return userMapper.selectByPrimaryKey(id);
}
}
报错:
解决方法:
Alt + Enter
:
编写 controller:UserController
添加一个对外查询的接口:
package cn.ys.user.controller;
import cn.ys.user.pojo.User;
import cn.ys.user.service.UserService;
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.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
@GetMapping("/{id}")
public User queryById(@PathVariable("id") Long id){
return userService.queryById(id);
}
}
项目结构:
启动并测试:
启动项目,访问接口:http://localhost:8081/user/7
3、服务调用者
创建工程
与上面类似,这里不再赘述,需要注意的是,我们调用 user-service
的功能,因此不需要 mybatis 相关依赖了。
pom
:
<?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>cn.ys.demo</groupId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<groupId>cn.ys.demo</groupId>
<artifactId>consumer-demo</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
</project>
编写代码
首先在启动类中注册 RestTemplate
:
package cn.ys;
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 ConsumerApplication {
@Bean
public RestTemplate restTemplate(){
return new RestTemplate();
}
public static void main(String[] args) {
SpringApplication.run(ConsumerApplication.class, args);
}
}
实体类 User
package cn.ys.consumer.pojo;
import lombok.Data;
import java.util.Date;
@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; // 创建日期
private Date updated; // 更新日期
private String note; // 备注
}
编写 controller
:
package cn.ys.consumer.controller;
import cn.ys.consumer.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.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
@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;
User user = restTemplate.getForObject(url, User.class);
return user;
}
}
启动测试:
在下面 方框中启动:
因为我们没有配置端口,那么默认就是8080,我们访问:http://localhost:8080/consumer/1
一个简单的远程服务调用案例就实现了。
有没有问题?
简单回顾一下,刚才我们写了什么:
use-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
流程如下:
存在什么问题?
- 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
其实上面说的问题,概括一下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
以上的问题,我们都将在 SpringCloud 中得到答案。