Mybatis之第一次使用

<?xml version="1.0" encoding="UTF-8" ?>
<!--mybatis-config.xml文件主要是提供连接数据库用的驱动，数据库名称，编码方式，账号密码-->
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--开启包扫描，使得后续的mapper.xml减少语句-->
    <typeAliases>
        <package name="com.ksea.pojo"/>
    </typeAliases>
    <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/how2java?characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <!--映射类配置的XML文件-->
    <mappers>
        <mapper resource="com/ksea/pojo/Category.xml"/>
    </mappers>
</configuration>

package com.ksea.pojo;

/**
 * @author :KSea
 * @description :
 * @createDate :2020/1/6
 */
public class Category {
    private int id;
    private String name;

    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;
    }
}

<?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.ksea.pojo">
    <!--映射,resultType表示与相关类关联，id提供给后续代码调用-->
    <select id="listCategory" resultType="Category">
    select * from   category_
    </select>
</mapper>

package com.ksea;

import com.ksea.pojo.Category;
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.InputStream;
import java.util.List;

/**
 * @author :KSea
 * @description :
 * @createDate :2020/1/6
 */
public class TestMybatis {
    public static void main(String[] args) throws IOException {
        String resource = "mybatis-config.xml";
        //使用Resources类来读取配置文件
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //SqlSessionFactory Mybatis的一个关键对象，用于根据转换为流的配置文件实例化一个mybatis的核心对象
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //持久化，类似于JDBC的Connection
        SqlSession session = sqlSessionFactory.openSession();

        //使用持久化后的示例调用配置的mapper中的id来进行sql语句调用
        List<Category> categoryList = session.selectList("listCategory");
        for (Category category :categoryList){
            System.out.println(category.getName());
        }
    }
}