测试：MyBatisDemo

MyBatis Demo

先创建一个 Maven 项目，名称为 MyBatis01。

之后创建并连接 MySQL 数据库，然后执行 sql 脚本：

CREATE DATABASE `mybatis`;USE `mybatis`;DROP TABLE IF EXISTS `user`;CREATE TABLE `user` (
`id` int(20) NOT NULL,
`name` varchar(30) DEFAULT NULL,
`pwd` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;insert  into `user`(`id`,`name`,`pwd`) values (1,'小孔','123456'),(2,'张三','abcdef'),(3,'李四','987654');

导入与 MyBatis 相关的依赖：

    <dependencies><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.26</version></dependency><!--mybatis--><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.2</version></dependency><!--junit--><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version></dependency></dependencies><build><resources><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>false</filtering></resource><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>false</filtering></resource></resources></build>

编写 MyBatis 核心配置文件，在 resources 目录下创建 mybatis-config.xml 文件，配置自己的数据库内容，包括地址、用户名、密码、驱动等： 

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><!--configuration核心配置文件--><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://localhost:3306/your_database_name?useSSl=trur&amp;sueUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=Asia/Shanghai"/><property name="username" value="your_username"/><property name="password" value="your_password"/></dataSource></environment></environments></configuration>

编写 MyBatis 工具类，创建 utils 目录，并新建 MybatiesUtils 类：

package com.khr.utils;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 java.io.IOException;
import java.io.InputStream;//sqlSessionFactory -->sqlSession
public class MybatisUtils {private static SqlSessionFactory sqlSessionFactory;//使用mybatis第一步，获取sqlSessionFactory对象static {try {String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);} catch (IOException e) {e.printStackTrace();}}//既然有了sqlSessionFactory,顾名思义，我们就可以从中获得sqlSession的实例了//sqlSession 完全包含了面向数据库执行SQL命令所需的所有方法public static SqlSession getSqlSession(){return sqlSessionFactory.openSession();}
}

编写 MyBatis 实体类，创建 pojo 目录，并新建 User 类：

package com.khr.pojo;public class User {private int id;  //idprivate String name;   //姓名private String pwd;   //密码public User(){}public User(int id, String name, String pwd) {this.id = id;this.name = name;this.pwd = pwd;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getPwd() {return pwd;}public void setPwd(String pwd) {this.pwd = pwd;}@Overridepublic String toString() {return "User{" +"id=" + id +", name='" + name + '\'' +", pwd='" + pwd + '\'' +'}';}
}

编写 Mapper 接口类，创建 dao 目录，并新建UserDao 接口：

package com.khr.dao;import com.khr.pojo.User;
import java.util.List;
public interface UserDao {List<User> getUserList();
}

在 dao 目录下创建 UserMapper.xml 配置文件：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace=绑定一个对应的Dao/Mapper接口-->
<mapper namespace="com.khr.dao.UserDao"><!--select查询语句--><select id="getUserList" resultType="com.khr.pojo.User">select * from mybatis.user</select>
</mapper>

将刚才创建的 UserMapper.xml 注册到 mybatis-config.xml 文件中，此后每编写一个 Mapper.xml 文件都要注册一次：

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><!--configuration核心配置文件--><configuration>……<mappers><mapper resource="com/khr/dao/UserMapper.xml"/></mappers></configuration>

编写测试类 UserDaoTest：

package com.khr.dao;import com.khr.pojo.User;
import com.khr.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;import java.util.List;public class UserDaoTest {//第一步：获得sqlSession对象SqlSession sqlSession;@Testpublic void test(){try {sqlSession = MybatisUtils.getSqlSession();//方式一：getMapperUserDao mapper = sqlSession.getMapper(UserDao.class);List<User> userList = mapper.getUserList();for (User user : userList) {System.out.println(user);}}catch (Exception e){e.printStackTrace();}finally {//关闭sqlSessionsqlSession.close();}}
}

运行结果：