SpirngBoot（整合篇 ==＞ 整合Mybatis

本章导学：

1. 在pom.xml导入Spring与mybatis整合的坐标依赖
2. 在application.yml中添加配置
3. 编写实体类
4. 编写Dao层与对应的mapper.xm配置文件
5. 在springboot配置文件中 整合mybatis 配置别名和扫描mapper映射文件 application.yml
6. 编写Service接口和实现类
7. 编写Controller
8. 使用PostMan最终测试

---

一、整合Mybatis

1,1、在pom.xml导入Spring与mybatis整合的坐标依赖

        <dependency>
            <groupId>org.mybatis.spring.bootgroupId>
            <artifactId>mybatis-spring-boot-starterartifactId>
            <version>2.1.3version>
        dependency>
 
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <scope>runtimescope>
        dependency>

 1.2、在application.yml中添加配置

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/db_brand
    username: root
    password: rootaaa

 我们去测试一下DataSource有没有成功导入

1.3、编写实体类

package com.brrbaii.pojo;
import lombok.*;
@Data
@NoArgsConstructor
@ToString
public class Brand {
    private int id;
    private String brandName;
    private String companyName;
    private int ordered;
    private String description;
    private int status;
    
}
 

1.4、 编写Dao层与对应的mapper.xm配置文件

package com.brrbaii.dao;
 
import com.brrbaii.pojo.Brand;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.ResultMap;
import org.apache.ibatis.annotations.Select;
import java.util.List;
 
//@Mapper
public interface BrandDao {
    @Select("select * from tb_brand")
    @ResultMap("BrandResult")
    List selectAll();
 
    @Select("select * from tb_brand where id = #{Id}")
    Brand selectById(Integer Id);
    
    @Delete("delete from tb_brand where id = #{Id}")
    boolean deleteById(Integer Id);
    
    boolean save(Brand brand);
 
    boolean updateById(Brand brand);
}

我们去resource目录下建一个Mapper包，专门放mapper.xml映射文件 

 BrandDao.xml代码如下：

"1.0" encoding="UTF-8" ?>
mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 
<mapper namespace="com.brrbaii.dao.BrandDao">
    <resultMap id="BrandResult" type="brand">
        <result column="brand_name" property="brandName" />
        <result column="company_name" property="companyName" />
    resultMap>
 
    <insert id="save">
        insert into
            tb_brand
        values
           (null, #{brandName}, #{companyName}, #{ordered}, #{description}, #{status})
    insert>
 
    <update id="updateById">
        update tb_brand
        <set>
            <if test="brandName!=null and brandName!= ''">
                brand_name = #{brandName},
            if>
            <if test="companyName!=null and companyName!= ''">
                company_name = #{companyName},
            if>
            <if test="description!=null and description!= ''">
                description = #{description},
            if>
            <if test="ordered!=null and ordered!= ''">
                ordered = #{ordered},
            if>
            <if test="status!=null and status!= ''">
                status = #{status},
            if>
        set>
        where id = #{id}
 
    update>
 
mapper>

注：我们在Dao层上并不直接添加@Mapper注解，因为如果后续程序有很多数据类，我们就得一个个的去添加@Mapper。我这里直接在启动类上指定扫描Dao层文件的位置 

 1.5、在springboot配置文件中 整合mybatis 配置别名和扫描mapper映射文件 application.yml

mybatis-plus:
  mapper-locations: classpath:mapper/*.xml     
  type-aliases-package: com.brrbaii.pojo

 这里的mapper-locations是我配置文件的路径 

1.6、编写Service接口和实现类

接口 ：

package com.brrbaii.service;
 
import com.brrbaii.pojo.Brand;
 
import java.util.List;
 
public interface BrandService {
 
    List selectAll();
 
    Brand selectById(Integer Id);
 
    boolean save(Brand brand);
 
    boolean delete(Integer Id);
 
    boolean updateById(Brand brand);
 
 
}

 实现类：

package com.brrbaii.service.Imp;
 
import com.brrbaii.dao.BrandDao;
import com.brrbaii.dao.MqDao;
import com.brrbaii.pojo.Brand;
import com.brrbaii.service.BrandService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import java.util.List;
 
@Service
public class BrandServiceImp implements BrandService {
 
    @Autowired
    private BrandDao brandDao;
 
 
 
    @Override
    public List selectAll() {
 
 
        List brands = brandDao.selectAll();
        return brands;
    }
 
    @Override
    public Brand selectById(Integer Id) {
        Brand brand = brandDao.selectById(Id);
        return brand;
    }
 
    @Override
    public boolean save(Brand brand){
        return brandDao.save(brand);
    }
 
    @Override
    public boolean delete(Integer Id) {
        return brandDao.deleteById(Id);
    }
 
    @Override
    public boolean updateById(Brand brand) {
        return brandDao.updateById(brand);
    }
 
 
}

1.7、编写Contorller层 

package com.brrbaii.controller;
 
import com.brrbaii.pojo.Brand;
import com.brrbaii.service.BrandService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
 
import java.util.ArrayList;
import java.util.List;
 
@RestController
@RequestMapping("/brands")
public class BrandController {
    @Autowired
    private BrandService brandService;
    @GetMapping
    public Result getAll(){
        List brands = brandService.selectAll();
        Integer code = checkMesg(brands) ? Code.SELECT_OK : Code.SELECT_ERR;
        return new Result(code,brands);
    }
 
    @GetMapping("/{Id}")
    public Result getById(@PathVariable Integer Id){
        Brand brand = brandService.selectById(Id);
        Integer code = checkMesg(brand) ? Code.SELECT_OK : Code.SELECT_ERR;
        String msg = checkMesg(brand) ? "查询成功": "查询失败";
        return new Result(code,brand,msg);
    }
 
    @PostMapping
    public Result save(@RequestBody Brand brand){
        boolean flag = brandService.save(brand);
        Integer code = flag ? Code.SAVE_OK : Code.SAVE_ERR;
        return new Result(code,flag);
    }
 
    @DeleteMapping("/{Id}")
    public Result delete(@PathVariable Integer Id){
        boolean flag = brandService.delete(Id);
        Integer code = flag ? Code.DELETE_OK : Code.DELETE_ERR;
        return new Result(code,flag);
    }
 
    @PutMapping()
    public Result update(@RequestBody Brand brand){
        boolean flag = brandService.updateById(brand);
        Integer code = flag ? Code.UPDATE_OK : Code.UPDATE_ERR;
        return new Result(code,flag);
    }
 
 
    public boolean checkMesg(Object o){
        return o != null ? true : false;
    }
 
}

 1.8、用PostMan最终测试

二、整合Mybatis-Plus

2.1、导入坐标

 
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <scope>runtimescope>
        dependency>
 
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>druid-spring-boot-starterartifactId>
            <version>1.2.6version>
        dependency>
 
        <dependency>
            <groupId>com.baomidougroupId>
            <artifactId>mybatis-plus-boot-starterartifactId>
            <version>3.5.2version>
        dependency>

2.2、修改yml配置 

mybatis-plus:
  #mapper文件的位置
  mapper-locations: classpath:mapper/*.xml
  #起别名
  type-aliases-package: com.brrbaii.pojo
  #开启日志
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  #为实体类增加前缀
  global-config:
    db-config:
      table-prefix: tb_

 2.3、Dao层继承BaseMapper 

mybaits-plus只在mybatis上做了增强，不做改动，如果我们需要编写自定义的SQl语句，还是可以创建一个xml文件去编写具体语句

"1.0" encoding="UTF-8" ?>
mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 
<mapper namespace="com.brrbaii.dao.MqDao">
 
 
    <select id="selectMapById" resultType="map">
        select * from tb_brand where id = #{id};
    select>
mapper>

mybatis-plus会自动把实体类的成员变量当做表的字段去查询，驼峰改为下划线_

比如companyName在查询时会被修改为company_name

如果实体类的成员变量和数据库列名不一致，我们可以用@TableFileId注解为它指定名称

 

2.4、 最终测试