猿蜕变10——一文学会ORM的正确打开姿势

山旮旯的胖子

发布于 2020-07-28 16:58:39

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发布于 2020-07-28 16:58:39

文章被收录于专栏：猿人工厂猿人工厂

看过之前的蜕变系列文章，相信你对springMVC有了一定的认识。对springMVC的常用功能已经有一个整体把握了。今天我们来开启新讨论，讲一讲数据库ORM操作方面的事情——Mybatis。

还记得我们之前是怎么访问数据库的吗？唉，加载驱动，建立连接，老老实实的写sql,盯着sql里的问号不放，执行sql,关闭连接……真的是一顿操作猛如虎，一看功能原地杵。

Java发展多年，自然不能老是这样搞了，已经有很多成熟的ORM框架支持我们以对象的方式访问数据库,让我们更加专注于业务逻辑的编写。

ORM，对象关系映射（ObjectRelational Mapping）是通过使用描述对象和数据库之间映射的元数据，将面向对象语言程序中的对象自动持久化到关系数据库中。我们使用ORM框架在关系型数据库和业务实体对象之间作一个映射，这样，我们在具体的操作业务对象的时候，就不需要再去和复杂的SQL语句打交道，只要像平时操作对象一样操作它就可以了。

ORM发展到今天，期间全自动ORM框架Hibernate经过短暂的繁荣（假象，大厂几乎不用，小厂为了开发速度拥抱），已经几乎凉凉，半自动化的Mybatis(之前叫Ibatis),经过多年大厂战火检验，大家还是意识到sql需要谨慎，莫要乱搞自动化生成的事情。Mybatis现在几乎算是如日中天一统江湖啦。嗯，还有JPA这个家伙，大家只当它是个做规范的吧。

接下来我们就用mybatais中使用TravelFavorite对象新增一条记录到数据库中，开启你的ORM的正确姿势。

1.创建一个web的maven项目，新增mybatis相关的依赖。除了mybatis的jar包之外，为了方便调试，这里要使用junit。

<!-- 本文主要是以测试用例的方式来使用 -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
   
     <dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.2.7</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
   <version>5.1.26</version>
</dependency>
<!-- 方便查看最终输出的sql -->
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

2.创建一个TravelRoute实体类：

package  com.pz.route.domain;
 
import  java.io.Serializable;
 
/**
 * 线路实体类
 * @author pangzi
 *
 */
publicclass TravelRoute implements Serializable {
 
    private Long travelRouteId;//线路id，必输
    private String travelRouteName;//线路名称，必输
    private Double travelRoutePrice;//价格，必输
    private String travelRouteIntroduce;//线路介绍
    private Integer travelRouteFlag;   //是否上架，必输，0代表没有上架，1代表是上架
    private String travelRouteDate;   //上架时间
    private String isThemeTour;//是否主题旅游，必输，0代表不是，1代表是
    private Integer travelRouteCount;//收藏数量
    private Integer travelRouteCid;//所属分类，必输
    private String travelRouteImage;//缩略图
    private Long travelRouteSellerId;//所属商家
    private Long travelSellerId;
       public Long getTravelRouteId() {
              returntravelRouteId;
       }
       public void setTravelRouteId(Long travelRouteId) {
              this.travelRouteId =travelRouteId;
       }
       public String getTravelRouteName() {
              returntravelRouteName;
       }
       publicvoidsetTravelRouteName(String travelRouteName) {
              this.travelRouteName =travelRouteName;
       }
       public Double getTravelRoutePrice() {
              returntravelRoutePrice;
       }
       publicvoidsetTravelRoutePrice(Double travelRoutePrice) {
              this.travelRoutePrice = travelRoutePrice;
       }
       public String getTravelRouteIntroduce() {
              returntravelRouteIntroduce;
       }
       publicvoidsetTravelRouteIntroduce(String travelRouteIntroduce) {
              this.travelRouteIntroduce = travelRouteIntroduce;
       }
      
      
       public Integer getTravelRouteFlag() {
              returntravelRouteFlag;
       }
       publicvoidsetTravelRouteFlag(Integer travelRouteFlag) {
              this.travelRouteFlag =travelRouteFlag;
       }
       public String getTravelRouteDate() {
              returntravelRouteDate;
       }
       publicvoidsetTravelRouteDate(String travelRouteDate) {
              this.travelRouteDate =travelRouteDate;
       }
       public String getIsThemeTour() {
              returnisThemeTour;
       }
       publicvoidsetIsThemeTour(String isThemeTour) {
              this.isThemeTour =isThemeTour;
       }
       public Integer getTravelRouteCount() {
              returntravelRouteCount;
       }
       publicvoidsetTravelRouteCount(Integer travelRouteCount) {
              this.travelRouteCount = travelRouteCount;
       }
       public Integer getTravelRouteCid() {
              returntravelRouteCid;
       }
       publicvoidsetTravelRouteCid(Integer travelRouteCid) {
              this.travelRouteCid =travelRouteCid;
       }
       public String getTravelRouteImage() {
              returntravelRouteImage;
       }
       public void setTravelRouteImage(String travelRouteImage) {
              this.travelRouteImage = travelRouteImage;
       }
       public Long getTravelRouteSellerId() {
              returntravelRouteSellerId;
       }
       public void setTravelRouteSellerId(Long travelRouteSellerId) {
              this.travelRouteSellerId = travelRouteSellerId;
       }
      
       public Long getTravelSellerId() {
              returntravelSellerId;
       }
       public void setTravelSellerId(Long travelSellerId) {
              this.travelSellerId = travelSellerId;
       }
       @Override
       public String toString() {
              return"TravelRoute [travelRouteId=" + travelRouteId
                            + ", travelRouteName=" + travelRouteName
                            + ", travelRoutePrice=" + travelRoutePrice
                            + ", travelRouteIntroduce=" + travelRouteIntroduce
                            + ", travelRouteFlag=" + travelRouteFlag + ", travelRouteDate="
                            + travelRouteDate + ", isThemeTour=" + isThemeTour
                            + ", travelRouteCount=" + travelRouteCount
                            + ", travelRouteCid=" + travelRouteCid + ", travelRouteImage="
                            + travelRouteImage + ", travelRouteSellerId="
                            + travelRouteSellerId + ",
travelSellerId=" + travelSellerId
                            + "]";
       }
}

3.创建表travel_route，虽然我们已经创建过了，这里还是给下建表SQL:

CREATE TABLE `travel_route` (
  `travel_route_id` int(11) NOT NULL AUTO_INCREMENT,
  `travel_route_name` varchar(500) COLLATE utf8_bin NOT NULL,
  `travel_route_price` double NOT NULL,
  `travel_route_introduce` varchar(1000) COLLATE utf8_bin DEFAULT NULL,
  `travel_route_flag` tinyint(1) NOT NULL,
  `travel_route_date` varchar(19) COLLATE utf8_bin DEFAULT NULL,
  `isThemeTour` tinyint(1) NOT NULL,
  `travel_route_count` int(11) DEFAULT '0',
  `travel_route_cid` int(11) NOT NULL,
  `travel_route_image` varchar(200) COLLATE utf8_bin DEFAULT NULL,
  `travel_route_seller_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`travel_route_id`),
  KEY `FK_category_route` (`travel_route_cid`),
  KEY `FK_seller_route` (`travel_route_seller_id`)
) ENGINE=InnoDB AUTO_INCREMENT=515 DEFAULT CHARSET=utf8 COLLATE=utf8_bin

4.编写用于操作数据库的dao的接口：

package  com.pz.route.dao;
 
import com.pz.route.domain.TravelRoute;
 
 
 
/**
 *
 * @author pangzi
 *
 */
publicinterface TravelRouteDao {
 
    /**
     * 添加线路
     * @param travelRoute
     */
    void add(TravelRoute travelRoute);
}

5.编写映射文件，一个又被称为mapper的文件，用于描述对象和数据库表字段的关系，以及编写SQL语句，具体的编写方法，后面会详细讲解。我们在resources目录下新建一个目录mapper, TravelRouteMapper.xml。虽然mapper的文件名没做强制要求，但是在实际开发过程中一般会以类名+Mapper.xml的规则命名。在TravelRouteMapper.xml中加入以下配置：

<?xml version="1.0"encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTDMapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.pz.route.dao.TravelRouteDao">
 
    <insert id="add"parameterType="com.pz.route.domain.TravelRoute">
       INSERT
        INTO travel_route
         (travel_route_name,travel_route_price,travel_route_introduce,travel_route_flag,travel_route_date,isThemeTour,travel_route_count,travel_route_cid,travel_route_image,travel_route_seller_id)
  values(#{travelRouteName},#{travelRoutePrice},#{travelRouteIntroduce},#{travelRouteFlag},#{travelRouteDate},#{isThemeTour},#{travelRouteCount},#{travelRouteCid},#{travelRouteImage},#{travelRouteSellerId})
    </insert>
   
 
 
</mapper>

6.在resources目录下编写mybatis的主配置文件这里命名为mybatis.xml编写以下内容

<?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://127.0.0.1:3306/route?characterEncoding=utf8"/>
                <property name="username"value="root"/>
                <property name="password"value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--注册映射文件-->
        <mapper resource="mapper/TravelRouteMapper.xml"/>
    </mappers>
</configuration>

7.增加日志相关配置在resources目录下新增文件log4j.properties，可以加入以下内容：

log4j.logger.com.pz.route.dao.TravelRouteDao=debug,console

8.创建接口TravelFavoriteDao的实现类：

package TravelFavoriteDao;
 
import java.io.IOException;
import java.io.InputStream;
 
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 com.pz.route.dao.TravelFavoriteDao;
import com.pz.route.domain.TravelFavorite;
 
public class TravelFavoriteDaoImpl implements TravelFavoriteDao {
        private SqlSession sqlSession;
 
       @Override
       public void add(TravelFavorite travelFavorite) {
              try {
            //读取主配置文件
            InputStream input = Resources.getResourceAsStream("mybatis.xml");
            //创建SqlSessionFactory对象
            SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(input);
            //创建SqlSession对象
            sqlSession = sessionFactory.openSession();
            //新增数据操作
            sqlSession.insert("com.pz.route.dao.TravelFavoriteDao.add", travelFavorite);
            //提交SqlSession
            sqlSession.commit();
 
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (sqlSession != null){
                sqlSession.close();
            }
        }
    }
 
 
}

9.使用junit编写测试用例，调用程序

package com.pz.route.test;
 
import org.junit.Test;
 
import com.pz.route.dao.TravelRouteDao;
import com.pz.route.dao.impl.TravelRouteDaoImpl;
import com.pz.route.domain.TravelRoute;
 
public class TestTravelRouteDao {
      
      
       @Test
    public void testAdd(){
              TravelRouteDao travelFavoriteDao =new TravelRouteDaoImpl();
              TravelRoute travelRoute = new TravelRoute();
             
              travelRoute.setTravelRouteName("测试线路");
              travelRoute.setTravelRoutePrice(999d);
              travelRoute.setTravelRouteDate("2019-10-25");
              travelRoute.setTravelRouteFlag(1);
              travelRoute.setIsThemeTour("1");
              travelRoute.setTravelRouteCount(0);
              travelRoute.setTravelRouteCid(1);
              travelRoute.setTravelRouteIntroduce("双导游服务，免收服务小费，周全照顾贴心服务随心出游！品尝越南特色国宝美食，升级一餐越式炸鸡火锅宴！");
              travelRoute.setTravelRouteImage("img/product/small/m3db4d2277b5df3d98597f79082ef92d6d.jpg");
              travelRoute.setTravelRouteSellerId(1L);
             
              travelRouteDao.add(travelRoute);
    }
 
 
}

10.执行测试用例：执行完毕后可以在数据库中找到新增的记录（注意：执行一次后由于主键的原因，我们需要修改参数才能再次执行程序）

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原始发表：2020-05-29，如有侵权请联系 cloudcommunity@tencent.com 删除

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