MyBatis新手教程，附代码和解析。

1.新建一个maven项目,并配置pom.xml。

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

    <groupId>org.example</groupId>
    <artifactId>MyBatis</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <!--1.MyBatis 3.4.5-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <!--2.mysql 8.0.12-->
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.12</version>
        </dependency>
        <!--3.log4j-->
        <!-- https://mvnrepository.com/artifact/log4j/log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>
</project>

2.建立如下图的项目结构

其中：admin.class源码为：
也就是你要操作的数据库的映射bean(ORM)

public class admin {
    private int id;
    private String username;
    private String password;

    public admin() {
    }

    public admin(int id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "admin{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

3.DAO层中的adminMapper:

/*用户持久层接口*/
public interface daoMapper {
    /*查询所有操作*/
    List<admin> findAll();
}

4.新建一个SqlMapConfig.xml放在resource目录下

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--mybatis的主配置文件-->
<configuration>
    <!--1.配置环境-->
    <environments default="mysql">
        <!--2.配置mysql的环境，注意default=mysql&id 是相同的-->
        <environment id="mysql">
            <!--3.配置事务的类型-->
            <transactionManager type="JDBC"></transactionManager>
            <!--4.配置数据源(也叫连接池)-->
            <dataSource type="POOLED">
                <!--5.配置连接池的四个基本属性-->
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value=""/>
                <property name="user" value=""/>
                <property name="password" value=""/>
            </dataSource>
        </environment>
    </environments>
    <!--指定映射配置文件的位置,映射配置文件指的是每个dao独立的配置文件-->
    <mappers>
        <mapper resource="com/young/dao/adminMapper.xml"></mapper>
    </mappers>
</configuration>

5.新建一个jdbc.proerties

url= jdbc:mysql://localhost:3306/db_hotel?useUnicode=true&characterEncoding=UTF-8\
driver=com.mysql.cj.jdbc.Driver
user=root
password=123

6.在resource 目录下新建com/young/dao/adminMapper.xml

<?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="com.young.dao.adminMapper">
    <select id="findAll">
        select * from user
    </select>
</mapper>

7.引入log4j

# rootLogger\u662F\u6240\u6709\u65E5\u5FD7\u7684\u6839\u65E5\u5FD7,\u4FEE\u6539\u8BE5\u65E5\u5FD7\u5C5E\u6027\u5C06\u5BF9\u6240\u6709\u65E5\u5FD7\u8D77\u4F5C\u7528
# \u4E0B\u9762\u7684\u5C5E\u6027\u914D\u7F6E\u4E2D,\u6240\u6709\u65E5\u5FD7\u7684\u8F93\u51FA\u7EA7\u522B\u662Finfo,\u8F93\u51FA\u6E90\u662Fcon
log4j.rootLogger=debug,con
# \u5B9A\u4E49\u8F93\u51FA\u6E90\u7684\u8F93\u51FA\u4F4D\u7F6E\u662F\u63A7\u5236\u53F0
log4j.appender.con=org.apache.log4j.ConsoleAppender
# \u5B9A\u4E49\u8F93\u51FA\u65E5\u5FD7\u7684\u5E03\u5C40\u91C7\u7528\u7684\u7C7B
log4j.appender.con.layout=org.apache.log4j.PatternLayout
# \u5B9A\u4E49\u65E5\u5FD7\u8F93\u51FA\u5E03\u5C40
log4j.appender.con.layout.ConversionPattern=%d{MM-dd HH:mm:ss}[%p]%c%n -%m%n

8.编写测试类

package com.young.dao;

import com.young.domain.admin;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.apache.log4j.lf5.util.Resource;
import org.junit.Test;

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

import static org.junit.Assert.*;

/**
 * Create by wuyang9769@163.com
 * Decorate:
 *
 * @author young_wu
 * @date 2020/11/27 0027 0:28
 * You can't be killed, it will only make you stronger
 */
public class daoMapperTest {
    @Test
    public void test() throws IOException {
        //1.读取配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        SqlSessionFactory build = sqlSessionFactoryBuilder.build(is);
        //3.使用工厂生产SqlSession对象
        SqlSession sqlSession = build.openSession();
        //4.使用SqlSession创建Dao接口的代理对象
        daoMapper mapper = sqlSession.getMapper(daoMapper.class);
        //5.使用代理对象执行方法
        List<admin> all = mapper.findAll();
        for(admin admin : all){
            System.out.println(admin);
        }
        //6.释放资源
        sqlSession.close();
        is.close();

    }
}

成功！

本文地址：https://blog.csdn.net/young_qin/article/details/110210657