Mybatis 01 环境搭建和基本使用

1.导包

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2.配置文件

<?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">
<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:3308/mybatis" />
                <property name="username" value="root" />
                <property name="password" value="210374520" />
            </dataSource>
        </environment>
    </environments>

</configuration>

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3.创建实体类

package com.dhl.beyond.shiyan1;

public class User {
    private int id;  //用户的Id 或者是 学号
    private String name; //姓名
    private int age; //年龄

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

4.创建Mapper文件

<?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.dhl.beyond.shiyan1.userMapper">
    <select id="getUser" parameterType="int" resultType="com.dhl.beyond.shiyan1.User">
        select * from users where id=#{id}
    </select>

</mapper>

5.注册

    <mappers>
        <mapper resource="com/dhl/beyond/shiyan1/userMapper.xml"/>
    </mappers>

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6.测试类

package com.dhl.beyond.shiyan1;

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 TestUser {
    public static void main(String[] args) throws IOException {
        String resource = "config.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.dhl.beyond.shiyan1.userMapper.getUser";
        //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);
    }
}