mybatis创建入门流程体验

mysql数据库中建表

drop table if exists tb_user;create table tb_user(id int primary key auto_increment,username varchar(20),password varchar(20),gender char(1),addr varchar(30)
);INSERT INTO tb_user VALUES (1, 'zhangsan', '123', '男', '北京');
INSERT INTO tb_user VALUES (2, '李四', '234', '女', '天津');
INSERT INTO tb_user VALUES (3, '王五', '11', '男', '西安');

IDEA中新建项目模块

pom文件中导入依赖

        <!--mybatis 依赖--><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.5</version></dependency><!--mysql 驱动--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.26</version></dependency>

在resource目录下添加mybatis-config.xml的配置文件

<?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><typeAliases><package name="com.itheima.pojo"/></typeAliases><!--environments：配置数据库连接环境信息。可以配置多个environment，通过default属性切换不同的environment--><environments default="development"><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><!--数据库连接信息--><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>  <!-- 连接路径为本地mysql--><property name="username" value="root"/><property name="password" value="root"/></dataSource></environment></environments><mappers><!--加载sql映射文件--><mapper resource=""/><!--Mapper代理方式-->
<!--        <package name="UserMapper.xml"/>--></mappers>
</configuration>

创建 pojo类

public class User {private Integer id;private String username;private String password;private String gender;private String addr;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getGender() {return gender;}public void setGender(String gender) {this.gender = gender;}public String getAddr() {return addr;}public void setAddr(String addr) {this.addr = addr;}@Overridepublic String toString() {  //重写toString()方法return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +", gender='" + gender + '\'' +", addr='" + addr + '\'' +'}';}
}

创建sql表映射的xml文件，通常命名由表名开头。

<?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:名称空间
--><mapper namespace="UserMapper">  <!-- 此处自定义命名空间 --><select id="selectAll" resultType="com.mybatis.User">  <!-- 此处id为该表的唯一标识 resultType为查询返回类型包下目录形式的pojo类 -->select *from tb_user;</select><!-- <select id="selectById" resultType="user">   官方原版结构select *from tb_user where id = #{id};</select>-->
</mapper>

在mybatis-config.xml文件中加载刚创建的sql表映射的xml文件

        <!--加载sql映射文件--><mapper resource="UserMapper.xml"/>

主程序入口测试代码

    public static void main(String[] args) throws IOException {//1. 获取SqlSessionFactory  注意此处的代码配置不需要记忆和理解，官方编写好直接复制使用即可String resource = "mybatis-config.xml"; //写为mybatis-config.xml配置文件的的路径InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);//2. 获取SqlSession对象SqlSession sqlSession = sqlSessionFactory.openSession();//3.执行sqlList<User> users = sqlSession.selectList("UserMapper.selectAll"); //此处传sql命名空间下的唯一标识//4.打印输出查看System.out.println(users);//5. 释放资源sqlSession.close();}

运行查看输出结果