MyBatis创建一个简单的demo

1.概念

ORMapping: Object Relationship Mapping 对象关系映射 对象指⾯面向对象
关系指关系型数据库
Java 到 MySQL 的映射，开发者可以以⾯面向对象的思想来管理理数据库。

2.使用mybatis

2.1 项目目录

2.2 新建 Maven ⼯工程，pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

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

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.11</version>
        </dependency>
        <dependency> <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.6</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>


</project>

2.3 新建数据表

 
use mybatis;
create table t_account(
id int primary key auto_increment,
username varchar(11),
password varchar(11),
age int
)

2.4 新建数据表对应的实体类 Account

package cc.insistor.entity;

import lombok.Data;

@Data
public class Account {
    private long id;
    private String username;
    private String password;
    private int age;

    public Account(long id, String username, String password, int age) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.age = age;
    }
}

2…5 使⽤原生接⼝

2.5.1 MyBatis 框架需要开发者⾃自定义 SQL 语句句，写在 Mapper.xml ⽂文件中，实际开发中，会为每个实体 类创建对应的 Mapper.xml ，定义管理理该对象数据的 SQL。

<?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">
<mapper namespace="cc.insistor.mapper.AccoutMapper">
    <insert id="save" parameterType="cc.insistor.entity.Account">
        insert into t_account(username,password,age) values(#{username},#{password},#{age})
    </insert>
</mapper>

• namespace 通常设置为⽂文件所在包+⽂文件名的形式。 insert 标签表示执⾏行行添加操作。
• select 标签表示执⾏行行查询操作。
• update 标签表示执⾏行行更更新操作。
• delete 标签表示执⾏行行删除操作。
• id 是实际调⽤用 MyBatis ⽅方法时需要⽤用到的参数。 parameterType 是调⽤用对应⽅方法时参数的数据类型。

2.5.2 在全局配置⽂文件 config.xml 中注册 AccountMapper.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>
    <!-- 配置MyBatis运⾏行行环境 -->
    <environments default="development">
        <environment id="development">
            <!-- 配置JDBC事务管理理 -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- POOLED配置JDBC数据源连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"></property>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&amp;characterEncoding=UTF-8"></property>
                <property name="username" value="root"></property>
                <property name="password" value="123456"></property>
            </dataSource>
        </environment>
    </environments>
    <!-- 注册AccountMapper.xml -->
    <mappers>
     <mapper resource="cc/insistor/mapper/AccountMapper.xml"></mapper>
    </mappers>
</configuration>

2.5.3 调⽤用 MyBatis 的原⽣生接⼝执⾏添加操作。

package cc.insistor.test;


import cc.insistor.entity.Account;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.InputStream;

public class Test {
    public static void main(String[] args) {
        //加载MyBatis配置⽂文件
        InputStream inputStream = Test.class.getClassLoader().getResourceAsStream("config.xml");
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        String statement = "cc.insistor.mapper.AccoutMapper.save";
        Account account = new Account(1L,"张三","123123",22);
        sqlSession.insert(statement,account);
        sqlSession.commit();
    }
}