MyBatis的快速入门
MyBatis的快速入门
查询user表中所有数据:
- 创建user表,添加数据
- 创建模块,导入坐标
- 编写MyBatis核心配置文件-->替换连接信息 解决硬编码问题
- 编写SQL映射文件-->统一管理sql语句,解决硬编码问题
- 编码
- 定义POJO类
- 加载核心配置文件,获取SqlSessionFactory对象
- 获取SqlSession对象,执行SQL语句
- 释放资源
1: 准备数据
CREATE DATABASE mybatis;
USE mybatis;
DROP TABLE IF EXISTS tb_user;
CREATE TABLE tb_user(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(20),
password VARCHAR(20),
gender CHAR(1),
addr VARCHAR(30)
);
INSERT INTO tb_user VALUES(1, 'zhangsan', '123', '男', '北京');
INSERT INTO tb_user VALUES(2, 'lisi', '234', '女', '天津');
INSERT INTO tb_user VALUES(3, '王五', '11', '男', '西安');
2:创建模块,导入坐标
<!--pom.xml-->
<dependencies>
<!--MyBatis依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.5</version>
</dependency>
<!--mysql依赖-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.46</version>
</dependency>
<!--junit 单元测试-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency>
<!-- 添加slf4j日志api -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.20</version>
</dependency>
<!-- 添加logback-classic依赖 -->
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.3</version>
</dependency>
<!-- 添加logback-core依赖 -->
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>1.2.3</version>
</dependency>
</dependencies>
3: 编写MyBatis核心配置文件
<!--mybatis-config.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">
<!--数据库连接信息-->
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="1234"/>
</dataSource>
</environment>
</environments>
<mappers>
<!--加载sql映射文件-->
<mapper resource="UserMapper.xml"/>
</mappers>
</configuration>
4: 编写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">
<!--
namespace: 名称空间
-->
<mapper namespace="test">
<select id="selectAll" resultType="com.charley.pojo.User">
select * from tb_user;
</select>
</mapper>
5: 编码
/**
* Mybatis 快速入门代码
*/
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,用它来执行sql
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();
}
}