具体操作
项目结构
引入项目依赖 pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.imooc</groupId>
<artifactId>mybatis</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
</properties>
<repositories>
<repository>
<id>aliyun</id>
<name>aliyun</name>
<url>https://maven.aliyun.com/repository/public</url>
</repository>
</repositories>
<!--引入MyBaties依赖-->
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.7</version>
</dependency>
<!--导入MySQL JDBC驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.25</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.2</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.2</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>创建实体类(Entity) Goods.java
package com.imooc.mybatis.entity;
import java.util.List;
public class Goods {
private Integer goodsId;//商品编号
private String title;//标题
private String subTitle;//子标题
private Float originalCost;//原始价格
private Float currentPrice;//当前价格
private Float discount;//折扣率
private Integer isFreeDelivery;//是否包邮 ,1-包邮 0-不包邮
private Integer categoryId;//分类编号
public Integer getGoodsId() {
return goodsId;
}
public void setGoodsId(Integer goodsId) {
this.goodsId = goodsId;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getSubTitle() {
return subTitle;
}
public void setSubTitle(String subTitle) {
this.subTitle = subTitle;
}
public Float getOriginalCost() {
return originalCost;
}
public void setOriginalCost(Float originalCost) {
this.originalCost = originalCost;
}
public Float getCurrentPrice() {
return currentPrice;
}
public void setCurrentPrice(Float currentPrice) {
this.currentPrice = currentPrice;
}
public Float getDiscount() {
return discount;
}
public void setDiscount(Float discount) {
this.discount = discount;
}
public Integer getIsFreeDelivery() {
return isFreeDelivery;
}
public void setIsFreeDelivery(Integer isFreeDelivery) {
this.isFreeDelivery = isFreeDelivery;
}
public Integer getCategoryId() {
return categoryId;
}
public void setCategoryId(Integer categoryId) {
this.categoryId = categoryId;
}
}
用 XML 方式创建映射器 goods.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">
<mapper namespace="goods">
<select id="selectAll" resultType="com.imooc.mybatis.entity.Goods">
select * from t_goods order by goods_id desc limit 10
</select>
</mapper>创建数据库信息文件 db.properties
driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/babytun?useUnicode=true&characterEncoding=UTF-8
username=root
password=19980617zqqxsc创建MyBatis的配置文件 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>
<properties resource="db.properties"/>
<!--设置成支持驼峰命名-->
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
<!--设置默认指向的数据库-->
<environments default="dev">
<!--配置环境，不同的环境不同的id名字-->
<environment id="dev">
<!-- 采用JDBC方式对数据库事务进行commit/rollback -->
<transactionManager type="JDBC"/>
<!--采用连接池方式管理数据库连接-->
<!--<dataSource type="POOLED">-->
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
<environment id="prd">
<!-- 采用JDBC方式对数据库事务进行commit/rollback -->
<transactionManager type="JDBC"/>
<!--采用连接池方式管理数据库连接-->
<dataSource type="POOLED">
<property value="com.mysql.jdbc.Driver" name="driver"/>
<property value="jdbc:mysql://192.168.1.155:3306/babytun?useUnicode=true&characterEncoding=UTF-8"
name="url"/>
<property value="root" name="username"/>
<property value="root" name="password"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mappers/goods.xml"></mapper>
</mappers>
</configuration>创建MyBatis的工具类 MyBatisUtils.java
package com.imooc.mybatis.utils;
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;
/**
* @Auther 徐士成
* @Date 2021-06-21 16:47
*/
public class MyBatisUtils {
//利用static(静态)属于类不属于对象,且全局唯一
private static SqlSessionFactory sqlSessionFactory = null;
//利用静态块在初始化类时实例化sqlSessionFactory
static {
Reader reader = null;
try {
reader = Resources.getResourceAsReader("mybatis-config.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
//初始化错误时,通过抛出异常ExceptionInInitializerError通知调用者
throw new ExceptionInInitializerError(e);
}
}
/**
* openSession 创建一个新的SqlSession对象
* @return SqlSession对象
*/
public static SqlSession openSession(){
return sqlSessionFactory.openSession();
}
/**
* 释放一个有效的SqlSession对象
* @param session 准备释放SqlSession对象
*/
public static void closeSession(SqlSession session){
if(session != null){
session.close();
}
}
}
通过Junit依赖进行查询测试
package com.imooc.mabatis;
import com.imooc.mybatis.entity.Goods;
import com.imooc.mybatis.utils.MyBatisUtils;
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.junit.Test;
import java.io.IOException;
import java.io.Reader;
import java.sql.Connection;
import java.util.List;
/**
* @Auther 徐士成
* @Date 2021-06-21 15:13
*/
public class MyBatisTest {
@Test
public void testSelectGoods(){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.openSession();
// 进行查询，传入的参数取的是在goods.xml文件的namespace名称和select id
List<Goods> list = sqlSession.selectList("goods.selectAll");
for (Goods goods : list) {
System.out.println(goods.getTitle());
}
} catch (Exception e) {
throw e;
} finally {
MyBatisUtils.closeSession(sqlSession);
}
}
}
数据库goods表创建语句
create table t_goods
(
goods_id int auto_increment comment '商品编号'
primary key,
title varchar(128) not null comment '商品名称',
sub_title varchar(256) null comment '子标题',
original_cost float not null comment '原价',
current_price float not null comment '折后价',
discount float not null comment '折扣(0~1)',
is_free_delivery int not null comment '是否包邮',
category_id int default 0 not null
)执行结果
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