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mybatis03

news 来源：原创 2025/6/5 7:25:53

一、springboot整合mybatis

1.1搭建环境

1.引入jar包

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--mybatis 提供的和boot整合的jar包-->
<dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.3.0</version>
</dependency><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope>
</dependency>
<dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional>
</dependency>

2.配置文件

server:port: 8080
spring:datasource:url: jdbc:mysql://localhost:3306/yan9driver-class-name: com.mysql.cj.jdbc.Driverusername: rootpassword: 123456
mybatis:configuration:map-underscore-to-camel-case: true  #开启下划线到驼峰式命名法自动映射type-aliases-package: com.hl.mybatis03.pojo #类型起别名mapper-locations: classpath:mappers/*.xmllogging:level:com.hl.mybatis03.mapper: debug

3.准备控制层，业务层，持久层

@RestController
@RequestMapping("/grade")
public class GradeController {@Autowiredprivate GradeService gradeService;//搜索 动态查询@RequestMapping("search")public List<Grade> searchGrade(Grade grade){return gradeService.searchGrade(grade);}// 批量保存@RequestMapping("saveBatch")public int saveBatch(List<Grade> grades) {return gradeService.saveBatch(grades);}
}

public interface GradeService {//搜索 动态查询List<Grade> searchGrade(Grade grade);// 批量保存int saveBatch(List<Grade> grades);
}

@Mapper
public interface GradeMapper {//搜索 动态查询List<Grade> searchGrade(Grade grade);// 批量保存int saveBatch(List<Grade> grades);
}

4.sqlMapper文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.hl.mybatis03.mapper.GradeMapper">
<!--    //搜索 动态查询-->
<!--    List<Grade> searchGrade(Grade grade);--><select id="searchGrade" resultType="Grade">select * from grade<where><if test="gradeName != null and gradeName !='' ">grade_name like concat('%',#{gradeName},'%')</if><if test="address != null and address !='' ">and address=#{address}</if></where></select>
<!--    // 批量保存-->
<!--    int saveBatch(List<Grade> grades);-->
</mapper>

1.2动态sql

<where> 添加where关键字，去除紧邻的 and 或者 or

<if> 动态判断 test=""

<foreach> 循环 collection=“list” item="obj" index="index"

<trim> 代替where和set prefix="where" prefixOverrides="and|or" prefix="set" suffixOverrides=","

<set> 动态更新去除最后的，

<choose> <when> <otherwise> case-when 选择一个条件执行

//搜索 动态查询
@RequestMapping("search")
public List<Grade> searchGrade(Grade grade){return gradeService.searchGrade(grade);
}
// 批量保存
@RequestMapping("saveBatch")
public int saveBatch(@RequestBody List<Grade> grades) {return gradeService.saveBatch(grades);
}

@Mapper
public interface GradeMapper {//搜索 动态查询List<Grade> searchGrade(Grade grade);// 批量保存int saveBatch(@Param("list") List<Grade> grades);
}

<!--    //搜索 动态查询-->
<!--    List<Grade> searchGrade(Grade grade);--><select id="searchGrade" resultType="Grade">select * from grade<where><if test="gradeName != null and gradeName !='' ">grade_name like concat('%',#{gradeName},'%')</if><if test="address != null and address !='' ">and address=#{address}</if></where></select>
<!--    // 批量保存-->
<!--    int saveBatch(@Param("list")List<Grade> grades);--><insert id="saveBatch">insert into grade(grade_name,address)values<foreach collection="list" item="obj" separator=",">(#{obj.gradeName},#{obj.address})</foreach></insert>

1.3分页

物理分页

每次从数据库表中查询指定条数的数据，返回给前端。

select * from grade limit 10; //第一页

select * from grade limit 11,10; //第二页

逻辑分页

一次性从表中查询所有数据，在客户端分页。

1.引入分页插件

<dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper-spring-boot-starter</artifactId><version>1.4.3</version>
</dependency>

2.使用分页插件

//搜索 动态查询+分页
@RequestMapping("search")
public PageInfo searchGrade(Grade grade,@RequestParam(defaultValue = "1") Integer pageNum,@RequestParam(defaultValue = "5") Integer pageSize){//开启分页插件 只能对紧邻的第一个sql语句进行分页PageHelper.startPage(pageNum,pageSize);//调用目标方法List<Grade> list = gradeService.searchGrade(grade);//封装分页对象PageInfo pageInfo = new PageInfo(list);return pageInfo;
}

1.4事务

编程式事务

connnect.setAutoCommit(false);
connnect.startTransaction();
dml;
connection.commit();|| rollback();

声明式事务

@Transactional
在对应的类上或者方法上声明，即可使用事务。

1.5多表关联映射

结果集映射

resultType ：自动结果集映射列名和属性名自动映射（相同或者满足驼峰式命名法）。

一般应用于单表操作。

resultMap: 手动结果集映射手动的一个个指定列名和属性名的映射关系。

一般用于多表关联映射。

一对多映射collection

<!--结果集手动映射-->
<!--手动指令列名和属性名的映射关系  type="java中的数据类型，目标数据类型"-->
<resultMap id="baseMap" type="Grade"><!--主键字段映射--><id property="id" column="id"></id><!--非主键字段--><result property="gradeName" column="grade_name"></result><result property="address" column="address"></result>
</resultMap>
<select id="searchGrade" resultMap="baseMap">select * from grade<trim prefix="where" prefixOverrides="and |or"><if test="gradeName != null and gradeName !='' ">grade_name like concat('%',#{gradeName},'%')</if><if test="address != null and address !='' ">and address=#{address}</if></trim>
</select>

一对一association

作业

1、自己创建一个新的项目，实现springboot和mybatis的整合（面试题）

"搭建SpringBoot+MyBatis项目主要分四步：首先引入mybatis-spring-boot-starter和数据库驱动依赖；接着在application.yml配置数据源和mapper.xml路径；然后创建实体类和带@Mapper注解的接口；最后在XML文件写SQL，Service层调用Mapper即可。"

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