mybatis快速入门代码

参考根据02-MyBatis快速入门_哔哩哔哩_bilibili

项目文件结构

1、创建表

tb_user

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for tb_user
-- ----------------------------
DROP TABLE IF EXISTS `tb_user`;
CREATE TABLE `tb_user`  (
  `id` int(11) NOT NULL,
  `username` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci NULL DEFAULT NULL,
  `password` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci NULL DEFAULT NULL,
  `gender` varchar(1) CHARACTER SET utf8 COLLATE utf8_unicode_ci NULL DEFAULT NULL,
  `addr` varchar(30) CHARACTER SET utf8 COLLATE utf8_unicode_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_unicode_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of tb_user
-- ----------------------------
INSERT INTO `tb_user` VALUES (1, '张三', '123', '男', '北京');
INSERT INTO `tb_user` VALUES (2, '李四', '456', '女', '天津');
INSERT INTO `tb_user` VALUES (3, '王五', '789', '男', '西安');

SET FOREIGN_KEY_CHECKS = 1;

User.java

package com.itheima.pojo;

//alt+insert 快速插入getter和setter
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;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", gender='" + gender + '\'' +
                ", addr='" + addr + '\'' +
                '}';
    }
}

2、创建模块导入坐标

pom.xml

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.37</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>

3、编写mybaits核心配置文件

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-config.dtd">
<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:///XXXXXX?useSSL=false"/>XXX写你的数据库名字
                <property name="username" value="XXXXXXX"/>XXX写你的mysql账号
                <property name="password" value="XXXXXXX"/>XXX写你的mysql密码
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--加载sql映射-->
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

4、编写sql映射文件

UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">

<!--namespace-名称空间-->

<mapper namespace="test">
    <select id="selectAll" resultType="com.itheima.pojo.User">
        select * from tb_user
    </select>
</mapper>

5、编码

MyBatisDemo.java

package com.itheima;
import com.itheima.pojo.User;
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;
import java.util.List;

//mybatis快速入门方法
public class MyBatisDemo {
    public static void main(String[] args) throws IOException {
        //1.加载mybatis的核心配置文件，获取SqlSeesionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //2.获取sqlSession对象，用它执行sql
        SqlSession mySqlSession=sqlSessionFactory.openSession();
        //3.执行sql
        List<User> users = mySqlSession.selectList("test.selectAll");
        System.out.println(users);
        //4.释放资源
        mySqlSession.close();
    }
}