JavaWeb开发教程：2023.3.31坚持第33天，JavaWeb-Mybatis基础操作

前言

记录时间：2023.3.31

已坚持学习第33天

java从入门到精通

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早上7：00到 12：00

下午2：00到 5：00

JavaWeb-mybatis基础操作总结

完成代码练习

SQL数据库表创建

create table user(
     id int unsigned primary key auto_increment comment 'ID',
     name varchar(100) comment '姓名',
     age tinyint unsigned comment '年龄',
     gender tinyint unsigned comment '性别, 1:男, 2:女',
     phone varchar(11) comment '手机号'
) comment '用户表';

insert into user(id, name, age, gender, phone) VALUES (null,'白眉鹰王',55,'1','18800000000');
insert into user(id, name, age, gender, phone) VALUES (null,'金毛狮王',45,'1','18800000001');
insert into user(id, name, age, gender, phone) VALUES (null,'青翼蝠王',38,'1','18800000002');
insert into user(id, name, age, gender, phone) VALUES (null,'紫衫龙王',42,'2','18800000003');
insert into user(id, name, age, gender, phone) VALUES (null,'光明左使',37,'1','18800000004');
insert into user(id, name, age, gender, phone) VALUES (null,'光明右使',48,'1','18800000005');


select * from user;




-- 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());





-- 根据ID删除数据
delete  from emp where id = 17;





-- 登录
select count(*) from emp where username = 'zhangwuji' and password = '123456';


select count(*) from emp where username = 'zhangwuji' and password = '111';


-- SQL注入
select count(*) from emp where username = 'wuieuwiueiwuiew' and password = '' or '1' = '1';

mybatis入门操作

1.目录结构

2.定义类

package cn.vqqc.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; //ID
    private String username; //用户名
    private String password; //密码
    private String name; //姓名
    private Short gender; //性别, 1 男, 2 女
    private String image; //图像url
    private Short job; //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'
    private LocalDate entrydate; //入职日期
    private Integer deptId; //部门ID
    private LocalDateTime createTime; //创建时间
    private LocalDateTime updateTime; //修改时间
}

3.empper接口方法

package cn.vqqc.mapper;

import cn.vqqc.pojo.Emp;
import org.apache.ibatis.annotations.*;

import java.time.LocalDate;
import java.util.List;

@Mapper
public interface EmpMapper {

    //根据ID删除数据
    @Delete("delete from emp where id = #{id}")
    public void delete(Integer id);
    //public int delete(Integer id);

    //新增员工
    @Options(useGeneratedKeys = true, keyProperty = "id")
    @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);


    //更新员工
    @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);


    //方案三: 开启mybatis的驼峰命名自动映射开关 --- a_cloumn ------> aColumn
    //根据ID查询员工
    @Select("select * from emp where id = #{id}")
    public Emp getById(Integer id);

    //方案一: 给字段起别名, 让别名与实体类属性一致
    //@Select("select id, username, password, name, gender, image, job, entrydate, " +
    //        "dept_id deptId, create_time createTime, update_time updateTime from emp where id = #{id}")
    //public Emp getById(Integer id);

    //方案二: 通过@Results, @Result注解手动映射封装
    //@Results({
    //        @Result(column = "dept_id", property = "deptId"),
    //        @Result(column = "create_time", property = "createTime"),
    //        @Result(column = "update_time", property = "updateTime")
    //})
    //@Select("select * from emp where id = #{id}")
    //public Emp getById(Integer id);



    //条件查询员工
    //方式一
    //@Select("select * from emp where name like '%${name}%' and gender = #{gender} and " +
    //        "entrydate between #{begin} and #{end} order by update_time desc ")
    //public List<Emp> list(String name, Short gender, LocalDate begin , LocalDate end);

    //方式二
//    @Select("select * from emp where name like concat('%',#{name},'%') and gender = #{gender} and " +
//            "entrydate between #{begin} and #{end} order by update_time desc ")
//    public List<Emp> list(String name, Short gender, LocalDate begin , LocalDate end);

    //动态条件查询
    public List<Emp> list(String name, Short gender, LocalDate begin , LocalDate end);


    //动态更新员工
    public void update2(Emp emp);


    //批量删除员工
    public void deleteByIds(List<Integer> ids);
}

4.连接数据库配置

#驱动类名称
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#数据库连接的url
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis
#连接数据库的用户名
spring.datasource.username=root
#连接数据库的密码
spring.datasource.password=1234

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

#开启mybatis的驼峰命名自动映射开关 a_column ------> aCloumn
mybatis.configuration.map-underscore-to-camel-case=true

5.启动测试类

package cn.vqqc;


import cn.vqqc.mapper.EmpMapper;
import cn.vqqc.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;
import java.util.Arrays;
import java.util.List;

@SpringBootTest
class SpringbootMybatisCrudApplicationTests {

    @Autowired
    private EmpMapper empMapper;

    //根据ID删除
    @Test
    public void testDelete(){
        //int delete = empMapper.delete(16);
        //System.out.println(delete);
        empMapper.delete(17);
    }

    //新增员工
    @Test
    public void testInsert(){
        //构造员工对象
        Emp emp = new Emp();
        emp.setUsername("Tom3");
        emp.setName("汤姆3");
        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);

        //执行新增员工信息操作
        empMapper.insert(emp);
        System.out.println(emp.getId());
    }

    //更新员工
    @Test
    public void testUpdate(){
        //构造员工对象
        Emp emp = new Emp();
        emp.setId(18);
        emp.setUsername("Tom1");
        emp.setName("汤姆1");
        emp.setImage("1.jpg");
        emp.setGender((short)1);
        emp.setJob((short)1);
        emp.setEntrydate(LocalDate.of(2000,1,1));
        emp.setUpdateTime(LocalDateTime.now());
        emp.setDeptId(1);

        //执行更新员工操作
        empMapper.update(emp);
    }


    //根据ID查询员工
    @Test
    public void testGetById(){
        Emp emp = empMapper.getById(20);
        System.out.println(emp);
    }


    //根据条件查询员工
    @Test
    public void testList(){
        //List<Emp> empList = empMapper.list("张", (short) 1, LocalDate.of(2010, 1, 1), LocalDate.of(2020, 1, 1));
        //List<Emp> empList = empMapper.list("张", null, null, null);
        //List<Emp> empList = empMapper.list("张", (short)1, null, null);
        //List<Emp> empList = empMapper.list(null, (short)1, null, null);
        List<Emp> empList = empMapper.list(null, null, null, null);
        System.out.println(empList);
    }


    //动态更新员工 - 更新ID为18的员工 username 更新为 Tom111, name更新为 汤姆111, gender更新为2
    @Test
    public void testUpdate2(){
        //构造员工对象
        Emp emp = new Emp();
        emp.setId(19);
        emp.setUsername("Tom222333");
//        emp.setName("汤姆222");
//        emp.setGender((short)1);
//        emp.setUpdateTime(LocalDateTime.now());

        //执行更新员工操作
        empMapper.update2(emp);
    }


    //批量删除员工 - 13,14,15
    @Test
    public void testDeleteByIds(){
        List<Integer> ids = Arrays.asList(13, 14, 15);
        empMapper.deleteByIds(ids);
    }
}

6.EmpMapper.xml的配置

<?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="cn.vqqc.mapper.EmpMapper">

    <sql id="commonSelect">
        select id, username, password, name, gender, image, job, entrydate, dept_id, create_time, update_time
        from emp
    </sql>

    <!-- 动态更新员工-->
    <update id="update2">
        update emp
        <set>
            <if test="username != null">username = #{username},</if>
            <if test="name != null">name = #{name},</if>
            <if test="gender != null">gender = #{gender},</if>
            <if test="image != null">image = #{image},</if>
            <if test="job != null">job = #{job},</if>
            <if test="entrydate != null">entrydate = #{entrydate},</if>
            <if test="deptId != null">dept_id = #{deptId},</if>
            <if test="updateTime != null">update_time = #{updateTime}</if>
        </set>
        where id = #{id}
    </update>

    <!--resultType: 单条记录封装的类型-->
    <select id="list" resultType="cn.vqqc.pojo.Emp">
        <include refid="commonSelect"/>
        <where>
            <if test="name != null">
                name like concat('%', #{name}, '%')
            </if>
            <if test="gender != null">
                and gender = #{gender}
            </if>
            <if test="begin != null and end != null">
                and entrydate between #{begin} and #{end}
            </if>
        </where>
        order by update_time desc
    </select>

    <!--批量删除员工 (18,19,20)-->
    <!--
        collection: 遍历的集合
        item: 遍历出来的元素
        separator: 分隔符
        open: 遍历开始前拼接的SQL片段
        close: 遍历结束后拼接的SQL片段
    -->
    <delete id="deleteByIds">
        delete  from emp where id in
        <foreach collection="ids" item="id" separator="," open="(" close=")">
            #{id}
        </foreach>
    </delete>

</mapper>

7.pom.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.0.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cn.vqqc</groupId>
    <artifactId>springboot-mybatis-crud</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-mybatis-crud</name>
    <description>springboot-mybatis-crud</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>3.0.0</version>
        </dependency>

        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>