数据持久化（Dao---Entity---mapper）

配置（application.yml）

server:port: 10086
​
spring:datasource:driver-class-name: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://127.0.0.1:3306/wiki?useUnicode=true&characterEncoding=utf8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&serverTimezone=UTC&useSSL=trueusername: rootpassword: jia******
​
mybatis:mapper-locations: classpath:/mapper/*.xml

写创建库表语句

drop table if exists `demo`;
create table `demo`
(`id`   bigint not null comment 'id',`name` varchar(50) comment '名称',`other_name` vachar(50) comment '代替名',primary key (`id`)
) engine = innodb default charset utf8mb4 comment ='测试';
​
insert into `demo` (id, name,other_name)VALUES (1, '测试', 'text');

写相应的实体

//使用lombok写实体---我是用的方式，build创建实体很方便
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
​
/*** @author Rui* @description demo实体类* @create 2024/7/5 16:58*/
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class DemoEntity {private Integer id;private String name;private String otherName;
​
}

//使用getter，setter
/*** @author Rui* @description demo实体类* @create 2024/7/5 16:58*/
​
public class DemoEntity {private Integer id;private String name;private String otherName;
​public Integer getId() { return id; }public void setId(Integer id) { this.id = id; } public String getName() { return name; }public void setName(String name) { this.name = name; }
​public String getOtherName() { return otherName; } public void setOtherName(String otherName) {  this.otherName = otherName; }
​public DemoEntity() { } public DemoEntity(Integer id, String name, String otherName) {this.id = id;this.name = name;this.otherName = otherName;}
}
​

写mapper

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace= "com.jiawa.wiki.dao.DemoDao">
​<resultMap id ="dateMap" type="com.jiawa.wiki.domain.DemoEntity"><id column="id" property="id"/><result column="name" property="name"/><result column="password" property="password"/></resultMap>
​<select id="queryAllDemoDate" resultType="com.jiawa.wiki.domain.DemoEntity">select * from `demo`</select>
</mapper>

写dao接口

import com.jiawa.wiki.domain.DemoEntity;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
​
/*** @author Rui* @description 提供给服务层service的接口* @create 2024/7/5 17:01*/
@Mapper
public interface DemoDao {List<DemoEntity> queryAllDemoDemo();
}

---

服务层对数据持久层的数据做处理

service

import com.jiawa.wiki.dao.DemoDao;
import com.jiawa.wiki.domain.DemoEntity;
import org.springframework.stereotype.Service;
​
import javax.annotation.Resource;
import java.util.List;
​
/*** @author Rui* @description 为controller层提供服务，对数据层的数据处理* @create 2024/7/5 17:19*/
@Service
public class DemoService {@Resourceprivate DemoDao DemoDao;
​public List<DemoEntity> selectAllDateDemo(){List<DemoEntity> DemoEntities = DemoDao.queryAllDemoDate();return DemoEntities;}
}
​

---

控制层接收服务层提供的数据，或者向服务层传递前端的数据

controller

import com.jiawa.wiki.domain.DemoEntity;
import com.jiawa.wiki.service.DemoService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
​
import javax.annotation.Resource;
import java.util.List;
​
/*** @author Rui * @description 接收服务层的数据，像服务层传递数据* @description return出去的数据，浏览器就可以接收到了，几乎所有格式* @create 2024/7/5 14:53*/
@Slf4j
@RestController
//注意是rest风格的controller
public class DemoController {
​@Resourceprivate DemoService DemoService;//get方法和post方法效果相同，但是post可以在url中不显示参数@RequestMapping(value = "/hello", method = RequestMethod.GET)public String Hello() {return "Hello world";}
​
//除了post、get还有delete很多方法    @RequestMapping(value = "/hello/post", method = RequestMethod.POST)public String HelloPost(String name) {return "Hello world " +name;}
​@RequestMapping(value = "/hello/queryAll", method = RequestMethod.GET)public List<DemoEntity> queryAllDateDemo() {return DemoService.selectAllDateDemo();}
}