Mybatis基本操作

目录

准备工作

删除操作

预编译SQL?

增加操作

获取返回的主键

?更新操作

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准备工作

• 准备数据库表 emp
• 创建一个新的springboot工程，选择引入对应的起步依赖（mybatis、mysql驱动、lombok）
• application.properties中引入数据库连接信息
• 创建对应的实体类 Emp（实体类属性采用驼峰命名）
• 准备Mapper接口 EmpMapper

目录结构如下

建表语句如下

-- 部门管理
create table dept(
    id int unsigned primary key auto_increment comment '主键ID',
    name varchar(10) not null unique comment '部门名称',
    create_time datetime not null comment '创建时间',
    update_time datetime not null comment '修改时间'
) comment '部门表';

insert into dept (id, name, create_time, update_time) values(1,'学工部',now(),now()),(2,'教研部',now(),now()),(3,'咨询部',now(),now()), (4,'就业部',now(),now()),(5,'人事部',now(),now());



-- 员工管理
create table emp (
  id int unsigned primary key auto_increment comment 'ID',
  username varchar(20) not null unique comment '用户名',
  password varchar(32) default '123456' comment '密码',
  name varchar(10) not null comment '姓名',
  gender tinyint unsigned not null comment '性别, 说明: 1 男, 2 女',
  image varchar(300) comment '图像',
  job tinyint unsigned comment '职位, 说明: 1 班主任,2 讲师, 3 学工主管, 4 教研主管, 5 咨询师',
  entrydate date comment '入职时间',
  dept_id int unsigned comment '部门ID',
  create_time datetime not null comment '创建时间',
  update_time datetime not null comment '修改时间'
) comment '员工表';

INSERT INTO emp
	(id, username, password, name, gender, image, job, entrydate,dept_id, create_time, update_time) VALUES
	(1,'jinyong','123456','金庸',1,'1.jpg',4,'2000-01-01',2,now(),now()),
	(2,'zhangwuji','123456','张无忌',1,'2.jpg',2,'2015-01-01',2,now(),now()),
	(3,'yangxiao','123456','杨逍',1,'3.jpg',2,'2008-05-01',2,now(),now()),
	(4,'weiyixiao','123456','韦一笑',1,'4.jpg',2,'2007-01-01',2,now(),now()),
	(5,'changyuchun','123456','常遇春',1,'5.jpg',2,'2012-12-05',2,now(),now()),
	(6,'xiaozhao','123456','小昭',2,'6.jpg',3,'2013-09-05',1,now(),now()),
	(7,'jixiaofu','123456','纪晓芙',2,'7.jpg',1,'2005-08-01',1,now(),now()),
	(8,'zhouzhiruo','123456','周芷若',2,'8.jpg',1,'2014-11-09',1,now(),now()),
	(9,'dingminjun','123456','丁敏君',2,'9.jpg',1,'2011-03-11',1,now(),now()),
	(10,'zhaomin','123456','赵敏',2,'10.jpg',1,'2013-09-05',1,now(),now()),
	(11,'luzhangke','123456','鹿杖客',1,'11.jpg',5,'2007-02-01',3,now(),now()),
	(12,'hebiweng','123456','鹤笔翁',1,'12.jpg',5,'2008-08-18',3,now(),now()),
	(13,'fangdongbai','123456','方东白',1,'13.jpg',5,'2012-11-01',3,now(),now()),
	(14,'zhangsanfeng','123456','张三丰',1,'14.jpg',2,'2002-08-01',2,now(),now()),
	(15,'yulianzhou','123456','俞莲舟',1,'15.jpg',2,'2011-05-01',2,now(),now()),
	(16,'songyuanqiao','123456','宋远桥',1,'16.jpg',2,'2010-01-01',2,now(),now()),
	(17,'chenyouliang','123456','陈友谅',1,'17.jpg',NULL,'2015-03-21',NULL,now(),now());

?Emp.java内容如下

package com.itheima.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.time.LocalDate;
import java.time.LocalDateTime;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Emp {
    private Integer id;
    private String username;
    private String password;
    private String name;
    private Short gender;
    private String image;
    private Short job;
    private LocalDate entrydate;
    private Integer deptId;
    private LocalDateTime createTime;
    private LocalDateTime updateTime;
}

删除操作

?

EmpMapper内容如下

package com.itheima.mapper;

import org.apache.ibatis.annotations.*;

@Mapper
public interface EmpMapper {
    //根据id删除数据
    @Delete("delete from emp where id = #{id}")
    public void delete(Integer id);//可以有返回值，返回影响的记录数,将void改成int

}

SpringbootMybatisCrudApplicationTests.java内容如下

package com.itheima;

import com.itheima.mapper.EmpMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class SpringbootMybatisCrudApplicationTests {

    @Autowired
    private EmpMapper empMapper;

    @Test
    public void testDelete(){
        empMapper.delete(17);
    }

}

运行后发现删除成功

预编译SQL?

性能更高，更安全(防止SQL注入)

可以在application.properties文件中加入如下指令，可以在控制台查看mybatis日志

#配置mybatis的日志，指定输出到控制台
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

在mybatis的Mapper接口中声明的SQL语句使用的#{}占位符，#{}会被？替代，生成预编译SQL

增加操作

EmpMapper内容如下

package com.itheima.mapper;

import com.itheima.pojo.Emp;
import org.apache.ibatis.annotations.*;

@Mapper
public interface EmpMapper {
    //根据id删除数据
    @Insert("insert into emp(username, name, gender, image, job, entrydate, dept_id, create_time, update_time)" +
            " values (#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")//注意驼峰命名法

    public void insert(Emp emp);

}

SpringbootMybatisCrudApplicationTests.java内容如下

package com.itheima;

import com.itheima.mapper.EmpMapper;
import com.itheima.pojo.Emp;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.time.LocalDate;
import java.time.LocalDateTime;

@SpringBootTest
class SpringbootMybatisCrudApplicationTests {

    @Autowired
    private EmpMapper empMapper;

    @Test
    public void testInsert(){
        Emp emp = new Emp();
        emp.setUsername("aw");
        emp.setName("awaw");
        emp.setImage("1.jpg");
        emp.setGender((short)1);
        emp.setJob((short)1);
        emp.setEntrydate(LocalDate.of(2000,1,1));
        emp.setCreateTime(LocalDateTime.now());
        emp.setUpdateTime(LocalDateTime.now());
        emp.setDeptId(1);
        empMapper.insert(emp);
    }

}

运行后发现新增成功

获取返回的主键

@Options(keyProperty = "id",useGeneratedKeys = true)

会自动将生成的主键值赋值给emp对象的id属性

EmpMapper内容如下

package com.itheima.mapper;

import com.itheima.pojo.Emp;
import org.apache.ibatis.annotations.*;

@Mapper
public interface EmpMapper {
    //根据id删除数据
    @Options(keyProperty = "id",useGeneratedKeys = true)//会自动将生成的主键值赋值给emp对象的id属性
    @Insert("insert into emp(username, name, gender, image, job, entrydate, dept_id, create_time, update_time)" +
            " values (#{username},#{name},#{gender},#{image},#{job},#{entrydate},#{deptId},#{createTime},#{updateTime})")

    public void insert(Emp emp);

}

SpringbootMybatisCrudApplicationTests.java内容如下

package com.itheima;

import com.itheima.mapper.EmpMapper;
import com.itheima.pojo.Emp;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.time.LocalDate;
import java.time.LocalDateTime;

@SpringBootTest
class SpringbootMybatisCrudApplicationTests {

    @Autowired
    private EmpMapper empMapper;

    @Test
    public void testInsert(){
        Emp emp = new Emp();
        emp.setUsername("tom3");
        emp.setName("tom3");
        emp.setImage("1.jpg");
        emp.setGender((short)1);
        emp.setJob((short)1);
        emp.setEntrydate(LocalDate.of(2000,1,1));
        emp.setCreateTime(LocalDateTime.now());
        emp.setUpdateTime(LocalDateTime.now());
        emp.setDeptId(1);
        empMapper.insert(emp);
        System.out.println(emp.getId());
    }

}

运行结果如下，发现返回了主键

?更新操作

EmpMapper内容如下

package com.itheima.mapper;

import com.itheima.pojo.Emp;
import org.apache.ibatis.annotations.*;

@Mapper
public interface EmpMapper {
    //根据id删除数据
    @Update("update emp set username = #{username}, name = #{name}, gender = #{gender}, image = #{image}," +
            " job = #{job}, entrydate = #{entrydate}, dept_id = #{deptId},update_time = #{updateTime} where id = #{id}")
    public void update(Emp emp);

}

?SpringbootMybatisCrudApplicationTests.java内容如下

package com.itheima;

import com.itheima.mapper.EmpMapper;
import com.itheima.pojo.Emp;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.time.LocalDate;
import java.time.LocalDateTime;

@SpringBootTest
class SpringbootMybatisCrudApplicationTests {

    @Autowired
    private EmpMapper empMapper;

    @Test
    public void testUpdate(){
        Emp emp = new Emp();
        emp.setId(21);
        emp.setUsername("hi");
        emp.setName("hello");
        emp.setImage("2.jpg");
        emp.setGender((short)1);
        emp.setJob((short)1);
        emp.setEntrydate(LocalDate.of(2000,1,1));
        emp.setCreateTime(LocalDateTime.now());
        emp.setUpdateTime(LocalDateTime.now());
        emp.setDeptId(1);
        empMapper.update(emp);
    }

}

查询emp数据表

运行之后发现更改成功