• create user table

create database mybatis;
use mybatis;
drop table if exists tb_user;
create table tb_user(
	id int primary key auto_increment,
    username varchar(20),
    password varchar(20),
    gender char(1),
    addr varchar(30)
);

insert into tb_user values(1, 'zhansan', '123', '男', '北京');
insert into tb_user values(2, '李四', '234', '男', '北京');
insert into tb_user values(3, '王五', '24', '男', '北京');
update tb_user set addr = '西安' where id = 3;

select * from tb_user

• 导入坐标(mybaits, junit, slf4j, logback) from maven

<?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-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.13</version>
        </dependency>

        <!-- <https://mvnrepository.com/artifact/com.mysql/mysql-connector-j> -->
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <version>8.0.32</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>jcl-over-slf4j</artifactId>
            <version>1.5.6</version>
        </dependency>

        <!-- <https://mvnrepository.com/artifact/ch.qos.logback/logback-classic> -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.4.5</version>
            <scope>test</scope>
        </dependency>
        <!-- <https://mvnrepository.com/artifact/ch.qos.logback/logback-core> -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.4.5</version>
        </dependency>

    </dependencies>

</project>

• 编写Mybatis 配置

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "<https://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:///mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="Gn230646"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

• 编写logback配置

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <!-- Send debug messages to System.out -->
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <!-- By default, encoders are assigned the type ch.qos.logback.classic.encoder.PatternLayoutEncoder -->
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{5} - %msg%n</pattern>
        </encoder>
    </appender>

    <logger name="com.javacodegeeks.examples.logbackexample.beans" level="INFO" additivity="false">
        <appender-ref ref="STDOUT" />
    </logger>

    <!-- By default, the level of the root level is set to DEBUG -->
    <root level="DEBUG">
        <appender-ref ref="STDOUT" />
    </root>
</configuration>

• 编写Sql 映射

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "<https://mybatis.org/dtd/mybatis-3-mapper.dtd>">
<mapper namespace="test">
    <select id="selectAll" resultType="org.example.User">
        select * from tb_user;
    </select>
</mapper>

• 定义POJO

package org.example;

public class User {
    private Integer id              ;
    private String username        ;
    private String password        ;
    private String gender          ;
    private String addr            ;

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getAddr() {
        return addr;
    }

    public void setAddr(String addr) {
        this.addr = addr;
    }

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

• code and demo

public class mybatisDemo {
    public static void main(String[] args) throws IOException {
        //加载核心配置文件，获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2. get sqlsessioin object
        SqlSession sqlSession = sqlSessionFactory.openSession();
        List<User> users =  sqlSession.selectList("test.selectAll");

        System.out.println(users);
				// release resource
        sqlSession.close();
    }
}