【MyBatis】建立第一个MyBatis_mybatis怎么创建-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_46157208/article/details/120331962

声明 ::: 本篇博客笔记来源于b站【狂神说Java】Mybatis最新完整教程IDEA版通俗易懂
视频整理; 非商业盈利

第一个Mybatis

- 1、搭建环境
完整项目下载

1、搭建环境

1.1,搭建数据库

CREATE DATABASE `mybatis`;

USE `mybatis`;

-- 创建user表，字段·ID·为主键
CREATE TABLE `user`(
`id` INT(20) NOT NULL PRIMARY KEY,
`name` VARCHAR(30) DEFAULT NULL,
`pwd`  VARCHAR(30) DEFAULT NULL
)ENGINE=INNODB DEFAULT CHARSET=utf8;

-- 向表格中插入三条数据
INSERT INTO `user`(`id`,`name`,`pwd`)VALUES
(1,'张三','123456'),
(2,'李四','234567'),
(3,'王五','345678')

新建项目 (( P2—第00:08分钟))

1,新建一个普通的maven项目

2,删除src目录;(把它当父工程)

3,导入maven依赖

   <!--导入依赖-->
    <dependencies>
		<!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</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>
            <scope>test</scope>
        </dependency>
    </dependencies>

1.2,创建一个模块

编写mybatis的核心配置文件 ((( P2—第00:22分钟)))

<?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.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    
    <!--每一个Mappr.XML都需要在Mybatis核心配置文件中注册! -->
    <mappers>
        <mapper resource="com/chq/dao/UserMapper.xml"/>
    </mappers>

</configuration>

编写mybatis工具类 ((( P2—第00:26分钟)))

//SqlSessionFactory  ---> sqlSession
public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;
    static {

        try {
            //使用mybatis获取sqlSessionFactory对象
            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，我们可以从中获得 SqlSession 的实例。
    // SqlSession 提供了在数据库执行 SQL 命令所需的所有方法
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();

    }

}

1.3,编写代码

实体类 ( P2—第00:32分钟)

public class User {
    private int id;
    private String name;
    private String pwd;

    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;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}

Dao接口 ( P2—第00:33分钟)

public interface UserDao {
    List<User> getUserList();

}

接口实现类由原来的UserDaoImpl转变为一个Mapper配置文件**((( P2—第00:36分钟)))**

<?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=绑定一个对应的Dao/Mapper接口    -->
<mapper namespace="com.chq.dao.UserDao">
    <!-- select查询语句 -->
    <select id="getUserList" resultType="com.chq.pojo.User">
        select * from mybatis.user;
    </select>
</mapper>

1.4,测试

((( P2—第00:45分钟)))

junit测试

public class UserDaoTest {

    @Test
    public void test(){

        //第一步：获得SqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        //执行SQL
        //方式一:getMapper
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List<User> userList = userDao.getUserList();

        //方式二(过时,建议方式一):
        //List<User> userList = sqlSession.selectList("com.chq.dao.UserDao.getUserList");
        
        
        for (User user : userList) {
            System.out.println(user);
        }

        //关闭SqlSession
        sqlSession.close();
    }
}