• 示例：
• 导入相关 jar 包的 Maven 坐标：

<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.5</version>
</dependency>
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.21</version>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13</version>
    <scope>test</scope>
</dependency>

• db.properties

jdbc.url=jdbc:mysql://192.168.134.100:3306/test?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true
jdbc.driverClass=com.mysql.cj.jdbc.Driver
jdbc.username=root
jdbc.password=123456

• log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
 <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
   <param name="Encoding" value="UTF-8" />
   <layout class="org.apache.log4j.PatternLayout">
    <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m  (%F:%L) \n" />
   </layout>
 </appender>
 <logger name="java.sql">
   <level value="debug" />
 </logger>
 <logger name="org.apache.ibatis">
   <level value="info" />
 </logger>
 <root>
   <level value="debug" />
   <appender-ref ref="STDOUT" />
 </root>
</log4j:configuration>

• Employee.java

package com.sunxiaping.domain;
import org.apache.ibatis.type.Alias;
@Alias("emp")
public class Employee {
    private Integer id;
    private String lastName;
    private String email;
    private String gender;
    public Employee() {
    }
    public Employee(Integer id, String lastName, String email, String gender) {
        this.id = id;
        this.lastName = lastName;
        this.email = email;
        this.gender = gender;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    @Override
    public String toString() {
        return "Employee{" +
                "id=" + id +
                ", lastName='" + lastName + '\'' +
                ", email='" + email + '\'' +
                ", gender='" + gender + '\'' +
                '}';
    }
}

• EmployeeMapper.java

package com.sunxiaping.mapper;
import com.sunxiaping.domain.Employee;
public interface EmployeeMapper {
    /**
     * 根据id查询员工的信息
     *
     * @param id
     * @return
     */
    Employee findById(Integer id);
    /**
     * 增加员工信息
     *
     * @param employee
     */
    void addEmp(Employee employee);
    /**
     * 修改员工信息
     *
     * @param employee
     */
    void updateEmp(Employee employee);
    /**
     * 根据id删除员工信息
     *
     * @param id
     */
    void deleteEmpById(Integer id);
}

• EmployeeMapper.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.sunxiaping.mapper.EmployeeMapper">
    <select id="findById" resultType="com.sunxiaping.domain.Employee">
        SELECT id,last_name as lastName,email,gender
        FROM employee
        WHERE id = #{id,jdbcType=INTEGER}
    </select>
    <insert id="addEmp">
        INSERT INTO employee (last_name,email,gender)
        VALUES (#{lastName,jdbcType=VARCHAR},#{email,jdbcType=VARCHAR},#{gender,jdbcType=VARCHAR})
    </insert>
    <update id="updateEmp">
        UPDATE employee
        SET last_name = #{lastName,jdbcType=VARCHAR},email = #{email,jdbcType=VARCHAR},gender=#{gender,jdbcType=VARCHAR}
        WHERE id = #{id,jdbcType=INTEGER}
    </update>
    <delete id="deleteEmpById">
        DELETE FROM employee
        WHERE id = #{id,jdbcType=INTEGER}
    </delete>
</mapper>

• mybatis-copnfig.xml

<?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">
<configuration>
    <properties resource="db.properties"></properties>
    <settings>
        <!-- 开启自动驼峰命名规则映射 -->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <!-- 使用${}引入db.properties属性文件中的内容 -->
                <property name="driver" value="${jdbc.driverClass}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <package name="com.sunxiaping.mapper"/>
    </mappers>
</configuration>

• 测试：

package com.sunxiaping;
import com.sunxiaping.domain.Employee;
import com.sunxiaping.mapper.EmployeeMapper;
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.junit.After;
import org.junit.Before;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
public class EmployeeTest {
    SqlSessionFactory sqlSessionFactory = null;
    SqlSession sqlSession = null;
    EmployeeMapper employeeMapper = null;
    @Before
    public void before() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        sqlSession = sqlSessionFactory.openSession(true);
        employeeMapper = sqlSession.getMapper(EmployeeMapper.class);
    }
    @After
    public void after() {
        if (null != sqlSession) {
            sqlSession.close();
        }
    }
    @Test
    public void testFindById() {
        Employee employee = employeeMapper.findById(1);
        System.out.println("employee = " + employee);
    }
    @Test
    public void testAddEmp() {
        Employee employee = new Employee();
        employee.setEmail("jerry@qq.com");
        employee.setGender("男");
        employee.setLastName("jerry");
        employeeMapper.addEmp(employee);
    }
    @Test
    public void testUpdateEmp(){
        Employee employee = employeeMapper.findById(2);
        employee.setGender("女");
        employeeMapper.updateEmp(employee);
    }
    @Test
    public void testDeleteEmpById(){
        employeeMapper.deleteEmpById(2);
    }
}