mybatis基本使用步驟如下： <br/> **1. 封裝工具類** ```java public class MybatisUtils { private static SqlSessionFactory sessionFactory = null; static { try { //讀取核心配置文件并初始化 SqlSessionFactory InputStream ins = Resources.getResourceAsStream("mybatis-config.xml"); sessionFactory = new SqlSessionFactoryBuilder().build(ins); } catch (IOException e) { e.printStackTrace(); } } /** * 連接數據庫 */ public static SqlSession createConnetion() { return sessionFactory.openSession(true); } /** * 關閉與數據庫的連接，每次調用createConnection()方法，都要調用該方法，以釋放資源 */ public static void close(SqlSession sqlSession) { if (sqlSession != null) { sqlSession.close(); } } } ``` **2. 封裝實體類** ```java @Data @NoArgsConstructor @AllArgsConstructor public class Student { private Integer id; private String name; private Date born; private String gender; } ``` **3. 封裝dao層** （1）*`com.example.learn.mybatis.dao.StudentDao`* ```java public interface StudentDao { /** * 統計學生的人數. */ int counts(); } ``` （2）*`resources/mapper/StudentMapper.xml`* ```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"> <!-- namespace命名空間，對應dao層的接口 --> <mapper namespace="com.example.learn.mybatis.dao.StudentDao"> <!-- id: 對應StudentDao接口中的counts方法名 resultType: counts方法的返回值類型 --> <select id="counts" resultType="int"> select count(1) from student </select> </mapper> ``` **4. 測試** ```java public class StudentTest { private static SqlSession sqlSession = null; @Test public void counts() { try { //1. 連接數據庫 sqlSession = MybatisUtils.createConnetion(); //2. 調用StudentDao接口中的counts方法 int counts = sqlSession.getMapper(StudentDao.class).counts(); System.out.println(counts); //5 } catch (Exception e) { e.printStackTrace(); } finally { //3. 關閉連接，釋放資源 MybatisUtils.close(sqlSession); } } } ```