前端访问数据 后端提供对应接口
Controller监听，Service处理数据，Mapper操作数据库
在 MyBatis 中，mapper.xml 文件用于编写SQL 映射语句，将 Java 对象和数据库表之间进行映射。
上一篇文章：generatorConfig.xml - 掘金 (juejin.cn)
使用generatorConfig.xml的重点
- 配置文件的地址
<!-- 引入配置文件 -->
<properties url="file:///D:/A/musicWebsite/src/main/resources/generator.properties"/>
- 生成实体类的地址
<!-- 生成实体类地址 -->
<javaModelGenerator targetPackage="com.yuze.musicwebsite.model"
targetProject="${project}" >
<!-- 是否在当前路径下新加一层schema,eg：fase路径com.packetXXX.model， true:com.packetXXX.model.[schemaName] -->
<property name="enableSubPackages" value="false"/>
<!-- 是否针对string类型的字段在set的时候进行trim调用 -->
<property name="trimStrings" value="true"/>
</javaModelGenerator>
- 生成mapxml的地址
<sqlMapGenerator targetPackage="mapper"
targetProject="${project}" >
<!-- 是否在当前路径下新加一层schema,eg：fase路径mapper， true:mapper.[schemaName] -->
<property name="enableSubPackages" value="false" />
</sqlMapGenerator>
- 生成client的接口dao的地址
<!-- 生成mapxml对应client，也就是接口dao -->
<javaClientGenerator targetPackage="com.yuze.musicwebsite.mapper"
targetProject="${project}" type="XMLMAPPER" >
<!-- 是否在当前路径下新加一层schema,eg：fase路径com.packetXXX.mapper， true:com.packetXXX.mapper.[schemaName] -->
<property name="enableSubPackages" value="false" />
</javaClientGenerator>
书写完成后检查各个类的所在包名是否正确 xml文件内的（如下图）是否是全称
正确位置放置如图
展开后（未展示即为里面是空的）（以下两张图）
完善阶段：如何运行该程序
笔者现在正在学习一个新项目 以该项目为例 我们想要运行localhost:8888/allUser1后得到数据
- 确定Mapper.xml有对应指令操作数据库
<select id="allUser1" resultMap="BaseResultMap">
select *
from consumer
</select>
- Mapper接口里面写入
@Repository
public interface ConsumerMapper extends BaseMapper<Consumer> {
//Test
List<Consumer> allUser1();
}
- Service接口写入
public interface ConsumerService extends IService<Consumer> {
//Test
List<Consumer> allUser1();
}
- Service实现类里写
package com.yuze.musicwebsite.service.impl;
@Service
public class ConsumerServiceImpl extends ServiceImpl<ConsumerMapper,Consumer>
implements ConsumerService{
@Autowired
private ConsumerMapper consumerMapper;
//Test
@Override
public List<Consumer> allUser1() {
return consumerMapper.allUser1();
}
}
- Controller写入
package com.yuze.musicwebsite.controller;
@RestController
public class ConsumerController {
@Autowired
private ConsumerService consumerService;
//test
@RequestMapping(value = "/allUser1", method = RequestMethod.GET)
public Object allUser1(){
return consumerService.allUser1();
}
}
- 项目运行主程序
@SpringBootApplication
@MapperScan("com.yuze.musicwebsite.mapper")
public class MusicWebsiteApplication {
public static void main(String[] args) {
SpringApplication.run(MusicWebsiteApplication.class, args);
}
}
用户视角的顺序
- 输入网站
localhost:8888/allUser1 - 访问的接口交给Controller层处理，Controller将 命令传给Service层
- Service层调用Mapper/Dao层的对应方法返回数据，注意：Mapper接口操作数据库依赖Mapper.xml文件
注意点
运行的Application文件运行后只对所在包下的所有包、类进行扫描
另一种不需要在xml文件中书写指令的代码模式
上面是编写代码从底层model到控制台思路，这篇从用户角度思路来写 用户输入网址localhost:8888/singer/sex/detail?sex=0 代表歌手中性别为女的信息 得出下图效果
- Controller层接收用户指令，进入对应方法
@RestController
public class SingerController {
@Autowired
private SingerService singerService;
// 根据歌手性别查找歌手
@GetMapping("/singer/sex/detail")
public R singerOfSex(@RequestParam int sex) {
return singerService.singerOfSex(sex);
}
- Controller将对应命令传给Service
接口：
public interface SingerService extends IService<Singer> {
R singerOfSex(Integer sex);
}
实现类：
@Service
public class SingerServiceImpl extends ServiceImpl<SingerMapper, Singer> implements SingerService {
@Autowired
private SingerMapper singerMapper;
@Override
public R singerOfSex(Integer sex) {
QueryWrapper<Singer> queryWrapper = new QueryWrapper<>();
queryWrapper.like("sex", sex);
return R.success(null, singerMapper.selectList(queryWrapper));
}
}
- Service调用Mapper操作数据库
@Repository
public interface SingerMapper extends BaseMapper<Singer> {
}
- Mapper.xml
<?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.yuze.musicwebsite.mapper.SingerMapper">
<resultMap id="BaseResultMap" type="com.yuze.musicwebsite.model.Singer">
<id column="id" jdbcType="INTEGER" property="id" />
<result column="name" jdbcType="VARCHAR" property="name" />
<result column="sex" jdbcType="TINYINT" property="sex" />
<result column="pic" jdbcType="VARCHAR" property="pic" />
<result column="birth" jdbcType="TIMESTAMP" property="birth" />
<result column="location" jdbcType="VARCHAR" property="location" />
<result column="introduction" jdbcType="VARCHAR" property="introduction" />
</resultMap>
<sql id="Base_Column_List">
id, name, sex, pic, birth, location, introduction
</sql>
</mapper>
- Request作为传递的参数
@Data
public class SingerRequest {
private Integer id;
private String name;
private Byte sex;
private String pic;
private Date birth;
private String location;
private String introduction;
}
- 与数据库表对应的实体类
@TableName(value = "singer")
@Data
public class Singer {
@TableId(type = IdType.AUTO)
private Integer id;
private String name;
private Byte sex;
private String pic;
private Date birth;
private String location;
private String introduction;
@Override
public String toString() {
return ToStringBuilder.reflectionToString(this);
}
}
