创建项目

项目名：mybatis-demo(-yuyongqing)自己的名字拼音；

点击进入 项目代码结构

准备数据库的数据

#删除mybatis_demo数据库
drop database if exists mybatis_demo;

#创建mybatis_demo数据库
create database mybatis_demo;

#使用mybatis_demo数据库
use mybatis_demo;

#创建account表
create table user (
id int auto_increment primary key,
username varchar(20),
age int,
score int
);

#新增数据
insert into user (id, username, age, score) values
(1,'peter', 18, 100), (2,'pedro', 24, 200),
(3,'jerry', 28, 500), (4,'mike', 12, 300),
(5,'tom', 27, 1000);

如图所示：

加入mybatis驱动包

<dependencies>
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.23</version>
</dependency>
</dependencies>

如图：
刷新Maven。

一、编辑代码

1、JDBCDemo.java

public class JDBCDemo {
public static void main(String[] args) throws Exception {
    //1.注册驱动
    Class.forName("com.mysql.cj.jdbc.Driver");
    //2.获取连接
    Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mybatis_demo", "root", "root");
    //3.获取Statement对象
    PreparedStatement preparedStatement = connection.prepareStatement("select * from user WHERE id = ?");
    preparedStatement.setInt(1, 1);
    //4.执行SQL语句返回结果集
    ResultSet resultSet = preparedStatement.executeQuery();
    //5.遍历结果集
    while (resultSet.next()) {
        System.out.println("username: " + resultSet.getString("username"));
        System.out.println("age: " + resultSet.getString("age"));
    }
    //6.释放资源
    resultSet.close();
    preparedStatement.close();
    connection.close();
}
}

2、运行结果

二、引入MyBatis依赖

<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.6</version>
</dependency>
<!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic -->
 <dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.3.0-alpha5</version>
<scope>test</scope>
</dependency>

1、刷新Maven。

2、在java下新建StartNoXml.java

StartNoXml.java配置如下：

 @SuppressWarnings({"SqlResolve", "SqlNoDataSourceInspection", "Duplicates"})
 public class StartNoXml {
public static void main(String[] args) throws SQLException {
    // 准备jdbc事务类
    JdbcTransactionFactory jdbcTransactionFactory = new JdbcTransactionFactory();
    // 配置数据源
    PooledDataSource dataSource = new PooledDataSource(
            "com.mysql.cj.jdbc.Driver",
            "jdbc:mysql://localhost:3306/mybatis_demo?useSSL=false",
            "root",
            "root");
    // 配置环境，向环境中指定环境id、事务和数据源
    Environment environment = new Environment.Builder("development")
            .transactionFactory(jdbcTransactionFactory)
            .dataSource(dataSource).build();
    // 新建 MyBatis 配置类
    Configuration configuration = new Configuration(environment);
    // 得到 SqlSessionFactory 核心类
    SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);
    // 开始一个 sql 会话
    SqlSession session = sqlSessionFactory.openSession();
    // 得到 sql 连接并运行 sql 语句
    PreparedStatement preStatement = session
            .getConnection()
            .prepareStatement("SELECT * FROM user WHERE id = ?");
    preStatement.setInt(1, 1);
    ResultSet result = preStatement.executeQuery();
    // 验证结果
    while (result.next()) {
        System.out.println("username: " + result.getString("username"));
        System.out.println("age: " + result.getString("age"));
    }
    // 关闭会话
    session.close();
}
}

3、运行结果

三、配置文件配置MyBatis

1、mybatis-config.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>
<!-- 环境变量 -->
<environments default="development">
    <environment id="development">
        <!-- 事务管理器 -->
        <transactionManager type="JDBC"/>
        <!-- 数据源 -->
        <dataSource type="POOLED">
            <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/mybatis_demo?useSSL=false"/>
            <property name="username" value="root"/>
            <property name="password" value="root"/>
        </dataSource>
    </environment>
</environments>
</configuration>

2、读取配置文件

 InputStream configuration = Resources.getResourceAsStream("mybatis-config.xml");

3、运行结果