Mybatis介绍

MyBatis是支持普通SQL查询，存储过程和高级映射的优秀持久层框架。MyBatis消除了几乎所有的JDBC代码和参数的手工设置以及对结果集的检索封装。MyBatis可以使用简单的XML或注解用于配置和原始映射，将接口和Java的POJO（Plain Old Java Objects，普通的Java对象）映射成数据库中的记录.

JDBC-àdbutils-àMyBatis-àHibernate

mybatis快速入门

编写第一个基于mybaits的测试例子:

2.1. 添加jar包

【mybatis】

mybatis-3.1.1.jar

【MYSQL驱动包】 mysql-connector-java-5.1.7-bin.jar

 

2.2. 建库+表

create database mybatis;

use mybatis;

CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(20), age INT);

INSERT INTO users(NAME, age) VALUES('Tom', 12);

INSERT INTO users(NAME, age) VALUES('Jack', 11);

 

添加Mybatis的配置文件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">

<property name="driver" value="com.mysql.jdbc.Driver" />

<property name="url" value="jdbc:mysql://localhost:3306/mybatis" />

<property name="username" value="root" />

<property name="password" value="root" />

</dataSource>

</environment>

</environments>

</configuration>

 

定义表所对应的实体类

public class User {

private int id;

private String name;

private int age;

    //get,set方法

}

 

定义操作users表的sql映射文件userMapper.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.atguigu.mybatis_test.test1.userMapper">

<select id="getUser" parameterType="int"

resultType="com.atguigu.mybatis_test.test1.User">

select * from users where id=#{id}

</select>

</mapper>

 

在conf.xml文件中注册userMapper.xml文件

<mappers>

<mapper resource="com/atguigu/mybatis_test/test1/userMapper.xml"/>

</mappers>

 

编写测试代码：执行定义的select语句

public class Test {

public static void main(String[] args) throws IOException {

String resource = "conf.xml";

//加载mybatis的配置文件（它也加载关联的映射文件）

Reader reader = Resources.getResourceAsReader(resource);

//构建sqlSession的工厂

SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

//创建能执行映射文件中sql的sqlSession

SqlSession session = sessionFactory.openSession();

//映射sql的标识字符串

String statement = "com.atguigu.mybatis.bean.userMapper"+".selectUser";

//执行查询返回一个唯一user对象的sql

User user = session.selectOne(statement, 1);

System.out.println(user);

}

}

 

 

 

3. 操作users表的CRUD

3.1. XML的实现

1). 定义sql映射xml文件：

<insert id="insertUser" parameterType="com.atguigu.ibatis.bean.User">

insert into users(name, age) values(#{name}, #{age});

</insert>

 

<delete id="deleteUser" parameterType="int">

delete from users where id=#{id}

</delete>

 

<update id="updateUser" parameterType="com.atguigu.ibatis.bean.User">

update users set name=#{name},age=#{age} where id=#{id}

</update>

 

<select id="selectUser" parameterType="int" resultType="com.atguigu.ibatis.bean.User">

select * from users where id=#{id}

</select>

 

<select id="selectAllUsers" resultType="com.atguigu.ibatis.bean.User">

select * from users

</select>

 

 

 

本教程由尚硅谷教育大数据研究院出品，如需转载请注明来源。