mybatis学习笔记（1）基本环境

1.pom引入

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.1</version>
        </dependency>
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.5</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.17</version>
        </dependency>
    </dependencies>

　　2. config配置。在resource下添加 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"/>
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value=""/>
                <property name="username" value=""/>
                <property name="password" value=""/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!-- 添加映射文件到Mybatis的全局配置文件中 -->
        <mapper resource="learn/mybatis/CarrierMapper.xml"/>
    </mappers>
</configuration>

　　3.添加开发需要的mapper，实体类

CarrierMapper.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
id：唯一标识
resultType：返回值类型
#{id}：从传过来的参数中取出id值
 -->
<mapper namespace="learn.mybatis.CarrierMapper">
    <select id="queryAll" resultType="learn.mybatis.Carrier">
        select id, carrier_no carrierNo, carrier_name carrierName, main_page mainPage from t_carrier  where is_deleted = 0
    </select>
</mapper>

　　CarrierMapper.java

package learn.mybatis;

import java.util.List;

/**
 * Create by tianqing on 2019/7/24.
 */
public interface CarrierMapper {
    List<Carrier>  queryAll();
}

　　

Carrier.java

public class Carrier {
    private Long id;

    private String carrierNo;

    private String carrierName;

    private String mainPage;

    /**
     * 承运商类型
     */
    private Integer carrierType;

    private Integer isDeleted;

    private String creator;

    private String editor;

    private Date createTime;

    private Date editTime;
    
    getset...
}

　　4.整体目录结构

5.运行main方法。

package learn.mybatis;

import com.google.gson.Gson;
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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.InputStream;
import java.util.List;

/**
 * Create by tianqing on 2019/7/23.
 */
public class MybatisLearn {
    private static final Logger logger = LoggerFactory.getLogger(MybatisLearn.class);

    public static void main(String[] args) throws Exception {
        //前三步都相同
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = factory.openSession();
        //这里不再调用SqlSession 的api，而是获得了接口对象，调用接口中的方法。
        CarrierMapper mapper = sqlSession.getMapper(CarrierMapper.class);
        List<Carrier> carriers = mapper.queryAll();
        Gson gson = new Gson();
        logger.info("[MybatisLearn - main] 结果：{}", gson.toJson(carriers));

    }
}

　　6.执行并打印。

跑起来以后。我们不着急多种用法，下一章大致研究下 mybatis怎么实现的