MyBatis学习（一）基本配置与使用

MyBatis学习（一）基本配置与使用

1、前期准备

文件具体架构图

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1、配置conf.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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <!-- 配置数据库信息 -->
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/xiao?serverTimezone=GMT%2B8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--   加载映射文件     -->
        <mapper resource="com/feng/entity/personMapper.xml"/>
    </mappers>
</configuration>

2、创建对应的表和实体类

package com.feng.entity;

public class Person {
    private int id;
    private String name;
    private int age;

    public Person(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }
    public Person() {
    }

    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 int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

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

对应mysql中的表如图所示：

3、配置对应的映射文件xxxMapper.xml

<?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="com.feng.entity.personMapper">

    <select id="queryPersonById" resultType="com.feng.entity.Person" parameterType="int">
         select * from person where id = #{id}
    </select>

</mapper>

4、创建对应的测试类

package com.feng.entity;

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.Reader;

public class TestMyBatis {
    public static void main(String[] args) throws IOException {
        // 1、加载MyBatis配置文件、为了访问数据库
        Reader reader = Resources.getResourceAsReader("com/feng/conf.xml");
        // 2、sqlSessionFactory -- connection
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 3、执行查询、需要所在映射文件的namespace + id 值
        String statement = "com.feng.entity.personMapper.queryPersonById";
        Person person = sqlSession.selectOne(statement, 1);
        System.out.println(person);
        // 4、关闭连接
        sqlSession.close();
    }
}

2、运行结果