mybatis Introduction and Quick Start mybatis

1.mybatis Introduction

mybatis common support sql queries, stored procedures, and the machine persistence map (the java objects stored in the database) frame. Jdbc code and virtually eliminating manual setting parameters and the result set retrieved capsule. mybatis mapping file may be used xml, to the interface entity classes dao bean.

2.mybatis Quick Start

1. The establishment of a database table users

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);

2. Establish the corresponding entity class Users

public class Users {

private int id;

private String name;

private int age;

public Users() {

super();

}

public Users(int id, String name, int age) {

super();

this.id = id;

this.name = name;

this.age = age;

}

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 "Users [id=" + id + ", name=" + name + ", age=" + age + "]";

}

3.建立相应映射文件UsersMapper.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">

<!--

select：sql查询语句的标签，

id：相当于方法名称，

parameterType：传入参数类型（输入类型），要写全类名

resultType：传出参数类型（输出类型），要写全类名

-->

<select id="selectById" parameterType="int"

resultType="com.zhiyou100.kfs.bean.Users">

select * from users where id=#{id}

</select>

</mapper>

4.建立mybatis的配置文件，并注册UserMapper.xml映射文件

<?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">

<!--

url：数据库地址

username：数据库用户名

password：数据库密码

-->

<property name="url"

value="jdbc:mysql://localhost:3306/mybatis" />

</dataSource>

</environment>

</environments>

</mappers>

</configuration>

5.在单元测试里测试

class TestMybatis {

@Test

void test() throws Exception {

//1.获取配置文件config.xml加入到io流中

InputStream inputStream = Resources.getResourceAsStream("config.xml");

//2.通过SqlSessionFatoryBuilder的builder创建sqlsessionfatory

SqlSessionFactory sqlSessionFatory = new SqlSessionFactoryBuilder().build(inputStream);

//3.通过sqlSessionFactory的openSession方法创建SqlSession

SqlSession sqlSession=sqlSessionFatory.openSession();

//4.调用sqlSession的selectOne来使用通过id查询一个用户

//第一个参数是映射文件的namespace.方法名，第二个参数是传入sql语句的参数，这里是id

Users user=sqlSession.selectOne("Test.selectById",1);

System.out.println(user);

//最后一个页是很重要的一个：关闭资源

sqlSession.close(); }

}