• mybatis小示例

    一般使用mybatis的环境，大多都是别人已经配置好的。直接用就好了，如何自己搭建呢？其实很简单。看官方的文档就可以解决了。主要为了学习mybatis最基础的配置。我文章中的方法不基于spring,一般很少会在真实项目中直接使用。我把我的搭建过程记录下来给有用的人吧。

    什么是 MyBatis？

    MyBatis 是一款优秀的持久层框架，它支持自定义 SQL、存储过程以及高级映射。MyBatis 免除了几乎所有的 JDBC 代码以及设置参数和获取结果集的工作。MyBatis 可以通过简单的 XML 或注解来配置和映射原始类型、接口和 Java POJO（Plain Old Java Objects，普通老式 Java 对象）为数据库中的记录。

    官方文档地址:
    https://mybatis.org/mybatis-3/zh/index.html

    强烈建议自行查看官方文档来操作。

    没有spring如何使用mybatis

    现在我身边基本大部分项目都在使用spring技术了，那么如果没有spring呢？如何用mybatis？

    建表

    mybatis怎么能少的了对表进行操作呢？就以下面的表为例吧!数据库就用mysql吧

    表结构

    create table qa_category
(
    category_id bigint auto_increment comment '分类ID'
        primary key,
    title       varchar(200)           not null comment '标题',
    sort        int(5)                 null comment '排序',
    create_by   varchar(64) default '' null comment '创建者',
    create_time datetime               null comment '创建时间',
    update_by   varchar(64) default '' null comment '更新者',
    update_time datetime               null comment '更新时间'
)
    comment '提问分类';

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    测试数据

    INSERT INTO qa_category (title, sort, create_by, create_time, update_by, update_time) VALUES ('Java', 1, 'itkey', '2022-05-09 17:18:50', '', '2022-05-09 17:27:35');
INSERT INTO qa_category (title, sort, create_by, create_time, update_by, update_time) VALUES ('Vue', 2, 'itkey', '2022-05-09 17:19:09', '', '2022-05-09 17:27:35');
INSERT INTO qa_category (title, sort, create_by, create_time, update_by, update_time) VALUES ('React', 3, 'itkey', '2022-05-10 10:46:28', '', '2022-05-10 11:05:27');
INSERT INTO qa_category (title, sort, create_by, create_time, update_by, update_time) VALUES ('mysql', 4, 'itkey', '2022-05-11 14:51:48', '', '2022-05-11 14:51:59');
INSERT INTO qa_category (title, sort, create_by, create_time, update_by, update_time) VALUES ('MacOS', 5, 'itkey', '2022-05-11 14:53:18', '', '2022-05-11 14:53:24');

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    代码

    本来想写细点的，发现也没有什么内容可以说的。我直接上代码吧。

    pom.xml

    mybatis-demo/pom.xml 这个文件的重点就是mysql，mybatis的依赖。

    
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>

    <groupId>org.examplegroupId>
    <artifactId>mybatis-demoartifactId>
    <version>1.0-SNAPSHOTversion>

    <properties>
        <maven.compiler.source>8maven.compiler.source>
        <maven.compiler.target>8maven.compiler.target>
    properties>

    <dependencies>
        
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>8.0.28version>
        dependency>

        <dependency>
            <groupId>org.mybatisgroupId>
            <artifactId>mybatisartifactId>
            <version>3.5.10version>
        dependency>

    dependencies>

project>


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    实体类

    mybatis-demo/src/main/java/cn/ycmit/domain/QaCategory.java

    package cn.ycmit.domain;



import java.util.Date;

/**
 * 问答分类对象 qa_category
 *
 * @author ycmit
 * @date 2022-05-09
 */
public class QaCategory
{
    private static final long serialVersionUID = 1L;

    /** 分类ID */
    private Long categoryId;

    /** 标题 */
    private String title;

    /** 排序 */
    private Integer sort;

    /**
     * 创建者
     */
    private String createBy;

    /**
     * 创建时间
     */
    private Date createTime;

    /**
     * 更新者
     */
    private String updateBy;

    /**
     * 更新时间
     */
    private Date updateTime;

    public void setCategoryId(Long categoryId)
    {
        this.categoryId = categoryId;
    }

    public Long getCategoryId()
    {
        return categoryId;
    }
    public void setTitle(String title)
    {
        this.title = title;
    }

    public String getTitle()
    {
        return title;
    }
    public void setSort(Integer sort)
    {
        this.sort = sort;
    }

    public Integer getSort()
    {
        return sort;
    }

    public String getCreateBy() {
        return createBy;
    }

    public void setCreateBy(String createBy) {
        this.createBy = createBy;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    public String getUpdateBy() {
        return updateBy;
    }

    public void setUpdateBy(String updateBy) {
        this.updateBy = updateBy;
    }

    public Date getUpdateTime() {
        return updateTime;
    }

    public void setUpdateTime(Date updateTime) {
        this.updateTime = updateTime;
    }

    @Override
    public String toString() {
        return "QaCategory{" +
                "categoryId=" + categoryId +
                ", title='" + title + '\'' +
                ", sort=" + sort +
                ", createBy='" + createBy + '\'' +
                ", createTime=" + createTime +
                ", updateBy='" + updateBy + '\'' +
                ", updateTime=" + updateTime +
                '}';
    }
}


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    mapper

    mybatis-demo/src/main/java/cn/ycmit/mapper/QaCategoryMapper.java

    package cn.ycmit.mapper;



import cn.ycmit.domain.QaCategory;

import java.util.List;

/**
 * 问答分类Mapper接口
 *
 * @author ycmit
 * @date 2022-05-09
 */
public interface QaCategoryMapper
{
    /**
     * 查询问答分类
     *
     * @param categoryId 问答分类主键
     * @return 问答分类
     */
    public QaCategory selectQaCategoryByCategoryId(Long categoryId);

    /**
     * 查询问答分类列表
     *
     * @param qaCategory 问答分类
     * @return 问答分类集合
     */
    public List<QaCategory> selectQaCategoryList(QaCategory qaCategory);

    /**
     * 新增问答分类
     *
     * @param qaCategory 问答分类
     * @return 结果
     */
    public int insertQaCategory(QaCategory qaCategory);

    /**
     * 修改问答分类
     *
     * @param qaCategory 问答分类
     * @return 结果
     */
    public int updateQaCategory(QaCategory qaCategory);

    /**
     * 删除问答分类
     *
     * @param categoryId 问答分类主键
     * @return 结果
     */
    public int deleteQaCategoryByCategoryId(Long categoryId);

    /**
     * 批量删除问答分类
     *
     * @param categoryIds 需要删除的数据主键集合
     * @return 结果
     */
    public int deleteQaCategoryByCategoryIds(Long[] categoryIds);
}


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    mybatis-config.xml

    mybatis-demo/src/main/resources/mybatis/mybatis-config.xml
    这是主配置文件：

    
DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/ry-vue?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8&allowMultiQueries=true"/>
                <property name="username" value="root"/>
                <property name="password" value="itkey123456"/>
            dataSource>
        environment>
    environments>
    <mappers>
        <mapper resource="mybatis/QaCategoryMapper.xml"/>
    mappers>
configuration>


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    QaCategoryMapper.xml

    mybatis-demo/src/main/resources/mybatis/QaCategoryMapper.xml
    内容如下：

    
DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.ycmit.mapper.QaCategoryMapper">

    <resultMap type="cn.ycmit.domain.QaCategory" id="QaCategoryResult">
        <result property="categoryId"    column="category_id"    />
        <result property="title"    column="title"    />
        <result property="sort"    column="sort"    />
        <result property="createBy"    column="create_by"    />
        <result property="createTime"    column="create_time"    />
        <result property="updateBy"    column="update_by"    />
        <result property="updateTime"    column="update_time"    />
    resultMap>

    <sql id="selectQaCategoryVo">
        select category_id, title, sort, create_by, create_time, update_by, update_time from qa_category
    sql>

    <select id="selectQaCategoryList" parameterType="cn.ycmit.domain.QaCategory" resultMap="QaCategoryResult">
        <include refid="selectQaCategoryVo"/>
        <where>
            <if test="title != null  and title != ''"> and title like concat('%', #{title}, '%')if>
            <if test="sort != null "> and sort = #{sort}if>
        where>
    select>

    <select id="selectQaCategoryByCategoryId" parameterType="Long" resultMap="QaCategoryResult">
        <include refid="selectQaCategoryVo"/>
        where category_id = #{categoryId}
    select>

    <insert id="insertQaCategory" parameterType="cn.ycmit.domain.QaCategory" useGeneratedKeys="true" keyProperty="categoryId">
        insert into qa_category
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="title != null and title != ''">title,if>
            <if test="sort != null">sort,if>
            <if test="createBy != null">create_by,if>
            <if test="createTime != null">create_time,if>
            <if test="updateBy != null">update_by,if>
            <if test="updateTime != null">update_time,if>
         trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="title != null and title != ''">#{title},if>
            <if test="sort != null">#{sort},if>
            <if test="createBy != null">#{createBy},if>
            <if test="createTime != null">#{createTime},if>
            <if test="updateBy != null">#{updateBy},if>
            <if test="updateTime != null">#{updateTime},if>
         trim>
    insert>

    <update id="updateQaCategory" parameterType="cn.ycmit.domain.QaCategory">
        update qa_category
        <trim prefix="SET" suffixOverrides=",">
            <if test="title != null and title != ''">title = #{title},if>
            <if test="sort != null">sort = #{sort},if>
            <if test="createBy != null">create_by = #{createBy},if>
            <if test="createTime != null">create_time = #{createTime},if>
            <if test="updateBy != null">update_by = #{updateBy},if>
            <if test="updateTime != null">update_time = #{updateTime},if>
        trim>
        where category_id = #{categoryId}
    update>

    <delete id="deleteQaCategoryByCategoryId" parameterType="Long">
        delete from qa_category where category_id = #{categoryId}
    delete>

    <delete id="deleteQaCategoryByCategoryIds" parameterType="String">
        delete from qa_category where category_id in
        <foreach item="categoryId" collection="array" open="(" separator="," close=")">
            #{categoryId}
        foreach>
    delete>
mapper>


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    测试类

    mybatis-demo/src/main/java/cn/ycmit/MybatisTest.java

    package cn.ycmit;



import java.io.InputStream;
import java.util.List;

import cn.ycmit.domain.QaCategory;
import cn.ycmit.mapper.QaCategoryMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MybatisTest {
    public static void main(String[] args) throws Exception {
        test();
    }

    public static void test() throws Exception{
        String resource = "mybatis/mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        try (SqlSession session = sqlSessionFactory.openSession()) {
            QaCategoryMapper mapper = session.getMapper(QaCategoryMapper.class);
            List<QaCategory> list = mapper.selectQaCategoryList(null);
            System.out.println(list);
        }

    }

}


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    执行结果：

    [QaCategory{categoryId=1, title='Java', sort=1, createBy='itkey', createTime=Mon May 09 17:18:50 CST 2022, updateBy='', updateTime=Mon May 09 17:27:35 CST 2022}, QaCategory{categoryId=2, title='Vue', sort=2, createBy='itkey', createTime=Mon May 09 17:19:09 CST 2022, updateBy='', updateTime=Mon May 09 17:27:35 CST 2022}, QaCategory{categoryId=3, title='React', sort=3, createBy='itkey', createTime=Tue May 10 10:46:28 CST 2022, updateBy='', updateTime=Tue May 10 11:05:27 CST 2022}, QaCategory{categoryId=4, title='mysql', sort=4, createBy='itkey', createTime=Wed May 11 14:51:48 CST 2022, updateBy='', updateTime=Wed May 11 14:51:59 CST 2022}, QaCategory{categoryId=5, title='MacOS', sort=5, createBy='itkey', createTime=Wed May 11 14:53:18 CST 2022, updateBy='', updateTime=Wed May 11 14:53:24 CST 2022}]

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    源码

    其实所有用到的源码我已经全部写到文章中了。为了方便给有用的人，我把我的项目打包分享如下：
    https://download.csdn.net/download/lxyoucan/86336480

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  • 原文地址：https://blog.csdn.net/lxyoucan/article/details/126162493