尚硅谷-mybatis快速入门，-mybatis快速入门

1. Mybatis介绍(ibatis)

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--->dbutils(自动封装)--->MyBatis--->Hibernate

2. mybatis快速入门

编写第一个基于mybaits的测试例子:

项目结构：

2.1. 添加jar包

2.2. 建库+表

2.3. 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="123456" />
			</dataSource>
		</environment>
	</environments>
	
</configuration>

2.4. 定义表所对应的实体类

2.5. 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.bean.userMapper">
	<select id="getUser" parameterType="int" resultType="com.atguigu.mybatis.bean.User">
		select * from users where id=#{id}
	</select>
</mapper>

2.6. 在conf.xml文件中注册userMapper.xml文件

<mappers>
	<mapper resource="com/atguigu/mybatis/bean/userMapper.xml"/>
</mappers>

2.7. 编写测试代码：执行定义的select语句

package com.atguigu.mybatis.test1;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.atguigu.mybatis.bean.User;

/**
 * mybatis快速入门
 */
public class Test1 {
	public static void main(String[] args) throws IOException {
		String resource = "conf.xml"; 
		//用类加载器加载mybatis的配置文件
		InputStream is = Test1.class.getClassLoader().getResourceAsStream(resource);
		//构建sqlSession的工厂
		SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
		//创建能执行映射文件中sql的sqlSession
		SqlSession session = factory.openSession();
		//映射sql的标识字符串
		String statement = "com.atguigu.mybatis.bean.userMapper.getUser";
		//执行查询返回一个唯一user对象的sql
		User user = session.selectOne(statement, 2);
		System.out.println(user);
	}
}