Mybatis的学习

这次学习了Mybatis的用法，并且跟着视频做了实际应用

1、创建user表，添加数据

2、创建Maven项目模块，导入坐标

4.0.0

<groupId>org.example</groupId>
<artifactId>mybites-demo</artifactId>
<version>1.0-SNAPSHOT</version>

<properties>
    <maven.compiler.source>11</maven.compiler.source>
    <maven.compiler.target>11</maven.compiler.target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>


<dependencies>
    <!--mybits 依赖-->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.5</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <!--mysql驱动 -->
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.23</version>
    </dependency>

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

3、编写Mybatis核心文件，替换信息连接（使代码简单化）

4、编写SQL映射文件（统一管理sql语句)

    <mapper resource="UserMapper.xml"/>
</mappers>

5、写UserMapper.xml

6、编码

package com.it;

import com.it.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;

public class MybatisDemo {
public static void main(String[] args) throws IOException {
//1.加载mybatis的核心配置文件，获取sqlSessionFactory
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

    //2.获取sqlSession对象
    SqlSession sqlSession=sqlSessionFactory.openSession();

    //3.执行sql
    List<User> users=sqlSession.selectList("test.selectAll");

    System.out.println(users);

    //4.释放资源
    sqlSession.close();
}

}

package com.it.pojo;

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 + '\'' +
            '}';
}

}

7、结果