mybatis练习
一.环境准备
1.数据库实始化
-- 创建tb_brand表
create table tb_brand (
/*id 主键*/
id int primary key auto_increment,
/* 品牌名称*/
brand_name varchar(20),
/* 企业名称 */
company_name varchar(20),
/* 排序字段*/ ordered int,
/* 描述信息*/ description varchar(100),
/* 状态：0：禁用 1：启用*/ status int );
-- 添加数据
insert into tb_brand (brand_name, company_name, ordered, description, status) values ('三只松鼠', '三只松鼠股份有限公司', 5, '好吃不上火', 0), ('华为', '华为技术有限公司', 100, '华为致力于把数字世界带入每个人、每个家庭、每个组织，构建万物互联的智能世界', 1), ('小米', '小米科技有限公司', 50, 'are you ok', 1);
2.mybatis.xml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">
<!--根元素-->
<configuration>
<!--加载外部配置文件-->
<properties resource="jdbc.properties"></properties>
<!--开启驼峰映射：把数据表中的带有下划线的字段，变为java的驼峰命名方式。user_name->username userName-->
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
<!--设置别名-->
<typeAliases>
<!--扫描指定的名,所包下的所有的类，都起了别名，别名格式：全部小写或驼峰命名-->
<package name="com.itheima.pojo"/>
<!-- <typeAlias type="com.itheima.pojo.User" alias="User"></typeAlias>-->
</typeAliases>
<!--配置数据源（数据库连接）-->
<environments default="dev">
<!--开发环境-->
<environment id="dev">
<!--事务管理器：按照jdbc默信的事务-->
<transactionManager type="JDBC"/>
<!--数据源(数据库连接池) mybatis有自带数据库连接池-->
<dataSource type="POOLED">
<!--连接数据库需要的4个参数：驱动、URL、登录名、密码-->
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
<!--测试环境-->
<environment id="test">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/hsp_db02?useUnicode=true&characterEncoding=utf-8&useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<!--映射映射相关文件-->
<mappers>
<!--方案1：指定关联的映射文件，通过映射文件在关联mapper接口-->
<!-- <mapper resource="com/itheima/dao/UserMapper.xml"/>-->
<!--方案1：指定关联的mapper接口（通过mapper接口关联映射文件）
要求：
1.映射文件名和mapper接口必须相同
2.映射文件和mapper接口存储在相同的路径下
-->
<!--指定要扫描的所有mapper接口的包路径-->
<package name="com.itheima.dao"/>
</mappers>
</configuration>
3.pojo类
public class Brand {
private Integer id;
private String brandName;
private String companyName;
private Integer ordered;
private String description;
private Integer status;
public Brand() {
}
public Brand(Integer id, String brandName, String companyName, Integer ordered, String description, Integer status) {
this.id = id;
this.brandName = brandName;
this.companyName = companyName;
this.ordered = ordered;
this.description = description;
this.status = status;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getBrandName() {
return brandName;
}
public void setBrandName(String brandName) {
this.brandName = brandName;
}
public String getCompanyName() {
return companyName;
}
public void setCompanyName(String companyName) {
this.companyName = companyName;
}
public Integer getOrdered() {
return ordered;
}
public void setOrdered(Integer ordered) {
this.ordered = ordered;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Integer getStatus() {
return status;
}
public void setStatus(Integer status) {
this.status = status;
}
@Override
public String toString() {
return "BrandDao{" +
"id=" + id +
", brandName='" + brandName + '\'' +
", companyName='" + companyName + '\'' +
", ordered=" + ordered +
", description='" + description + '\'' +
", status=" + status +
'}';
}
}
4.BrandMapper接口
package com.itheima.dao;
import com.itheima.pojo.Brand;
import java.util.List;
public interface BrandMapper {
/**
* 查询所有品牌
* @return
*/
public List<Brand> findAllBrand();
}
5.BrandMapper.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">
<!--利用namespace属性，绑定当前映射文件和mapper接口映射关联-->
<mapper namespace="com.itheima.dao.BrandMapper">
<!--使用resultMap解决查询结果中的字段名和java实体类中不一致问题-->
<resultMap id="brandMap" type="com.itheima.pojo.Brand" autoMapping="true">
<!--id标签：配置数据表的主键和实体类中的属性映射-->
<id column="id" property="id"></id>
<!--result标签：配置数据表中非主键字段和实体类的属性映射-->
<result column="brand_name" property="brandName"></result>
<result column="company_name" property="companyName"></result>
</resultMap>
<sql id="brandFields">
id,
brand_name,
company_name,
ordered,
description,
status
</sql>
<select id="findAllBrand" resultMap="brandMap">
select <include refid="brandFields"/> from tb_brand
</select>
<!--根据id查询一行数据-->
<select id="findBrandById" resultType="com.itheima.pojo.Brand" parameterType="int">
SELECT
id,
brand_name as brandName,
company_name as companyName,
ordered,
description,
status
FROM tb_brand
where id=#{id}
</select>
</mapper>
6.测试代码
public class MybatisTest {
@Test
public void testFindAllBrand(){
//使用SqlSessionFactory工厂类，创建SqlSession
SqlSession sqlSession = MybatisUtil.openSession();
//利用sqlSession，创建一个代理对象
BrandMapper sessionMapper = sqlSession.getMapper(BrandMapper.class);
//使用代理对象和方法查询用户数据
List<Brand> brandList = sessionMapper.findAllBrand();
//释放资源
MybatisUtil.closeSqlSession(sqlSession);
//测试用户数据
for (Brand brand:brandList){
System.out.println(brand);
}
}
}
二.mybatis占位符
参数占位符详解：
mybatis提供了两种参数占位符：
${key}：在核心配置文件中获取外部配置文件中的数据;在映射文件中做为sql的占位符参数使用（注意细节：需要使用@Param(“参数”))
#{key}:在映射文件中做为sql的占位符参数使用
#{key}和${key}的区别
#{}：底层使用的是 PreparedStatement 对sql进行预编译，使用占位符。好处：防止SQL注入
2024-01-15 17:57:11.300 [DEBUG] com.itheima.dao.BrandMapper.findBrandById [main] : ==> Preparing: SELECT id, brand_name as brandName, company_name as companyName, ordered, description, status FROM tb_brand where id=?
2024-01-15 17:57:11.398 [DEBUG] com.itheima.dao.BrandMapper.findBrandById [main] : ==> Parameters: 3(Integer)
2024-01-15 17:57:11.437 [TRACE] com.itheima.dao.BrandMapper.findBrandById [main] : <== Columns: id, brandName, companyName, ordered, description, status
2024-01-15 17:57:11.437 [TRACE] com.itheima.dao.BrandMapper.findBrandById [main] : <== Row: 3, 小米, 小米科技有限公司, 50, are you ok, 1
2024-01-15 17:57:11.441 [DEBUG] com.itheima.dao.BrandMapper.findBrandById [main] : <== Total: 1
${} ：底层使用的是 Statement，拼接SQL，会存在SQL注入问题
2024-01-15 17:58:37.816 [DEBUG] com.itheima.dao.BrandMapper.findBrandById [main] : ==> Preparing: SELECT id, brand_name as brandName, company_name as companyName, ordered, description, status FROM tb_brand where id=3
2024-01-15 17:58:37.922 [DEBUG] com.itheima.dao.BrandMapper.findBrandById [main] : ==> Parameters:
2024-01-15 17:58:37.966 [TRACE] com.itheima.dao.BrandMapper.findBrandById [main] : <== Columns: id, brandName, companyName, ordered, description, status
2024-01-15 17:58:37.968 [TRACE] com.itheima.dao.BrandMapper.findBrandById [main] : <== Row: 3, 小米, 小米科技有限公司, 50, are you ok, 1
2024-01-15 17:58:37.976 [DEBUG] com.itheima.dao.BrandMapper.findBrandById [main] : <== Total: 1
三.条件查询
1.-Map集合作为SQL参数
brandMapper.xml
<!--根据条件查询品牌数据-->
<select id="findBrandByCondition" resultMap="brandMap">
SELECT
id,
brand_name,
company_name,
ordered,
description,
status
FROM tb_brand
WHERE brand_name=#{brandName}
AND
company_name=#{companyName}
AND
status=#{status}
</select>
<select id="findBrandByCondition2" resultMap="brandMap">
SELECT
id,
brand_name,
company_name,
ordered,
description,
status
FROM tb_brand
WHERE brand_name=#{brandName}
AND
company_name=#{companyName}
AND
status=#{status}
</select>
<select id="findBrandByCondition3" resultMap="brandMap">
SELECT
id,
brand_name,
company_name,
ordered,
description,
status
FROM tb_brand
WHERE brand_name=#{brandname}
AND
company_name=#{companyname}
AND
status=#{status}
</select>
brandMapper接口
/**
* 根据条件，查询品牌数据
* @param brandName 品牌名称
* @param companyName 公司名称
* @param status 状态
* @return 返回的数据
*/
//当方法中传递的参数有2个或以上时，需要使用@Param注解声明占位符参数
public List<Brand> findBrandByCondition(
@Param("brandName") String brandName,
@Param("companyName") String companyName,
@Param("status") int status);
public List<Brand> findBrandByCondition2(Brand brand);
public List<Brand> findBrandByCondition3(Map paramMap);//mpa[key=value]
测试代码
@Test
public void testFindBrandByCondition3(){
//使用SqlSessionFactory工厂类，创建SqlSession
SqlSession sqlSession = MybatisUtil.openSession();
//利用sqlSession，创建一个代理对象
BrandMapper sessionMapper = sqlSession.getMapper(BrandMapper.class);
//使用代理对象和方法查询用户数据
Map map=new HashMap();
map.put("brandname","华为");
map.put("companyname","华为技术有限公司");
map.put("status",1);
List<Brand> brandList = sessionMapper.findBrandByCondition3(map);
//释放资源
MybatisUtil.closeSqlSession(sqlSession);
for (Brand brand2:brandList){
System.out.println(brand2);
}
}
@Test
public void testFindBrandByCondition2(){
//使用SqlSessionFactory工厂类，创建SqlSession
SqlSession sqlSession = MybatisUtil.openSession();
//利用sqlSession，创建一个代理对象
BrandMapper sessionMapper = sqlSession.getMapper(BrandMapper.class);
//使用代理对象和方法查询用户数据
Brand brand=new Brand();
brand.setBrandName("华为");
brand.setCompanyName("华为技术有限公司");
brand.setStatus(1);
List<Brand> brandList = sessionMapper.findBrandByCondition2(brand);
//释放资源
MybatisUtil.closeSqlSession(sqlSession);
for (Brand brand2:brandList){
System.out.println(brand2);
}
}
@Test
public void testFindBrandByCondition(){
//使用SqlSessionFactory工厂类，创建SqlSession
SqlSession sqlSession = MybatisUtil.openSession();
//利用sqlSession，创建一个代理对象
BrandMapper sessionMapper = sqlSession.getMapper(BrandMapper.class);
//使用代理对象和方法查询用户数据
List<Brand> brandList = sessionMapper.findBrandByCondition("华为","华为技术有限公司",1);
//释放资源
MybatisUtil.closeSqlSession(sqlSession);
for (Brand brand:brandList){
System.out.println(brand);
}
}
2.动态SQL
2.1 if
<!--根据条件查询品牌数据-->
<select id="findBrandByCondition" resultMap="brandMap">
SELECT
id,
brand_name,
company_name,
ordered,
description,
status
FROM tb_brand
WHERE 1=1
<if test="brandName !=null ">
AND brand_name=#{brandName}
</if>
<if test="companyName !=null ">
AND company_name=#{companyName}
</if>
<if test="status !=null ">
AND status=#{status}
</if>
</select>
2.2 where
where标签：代替sql语句中的where关键字可以自动去除sql语句中的where 条件里面多余的or或and
<select id="findBrandByCondition2" resultMap="brandMap">
SELECT
id,
brand_name,
company_name,
ordered,
description,
status
FROM tb_brand
<where>
<if test="brandName !=null ">
AND brand_name=#{brandName}
</if>
<if test="companyName !=null ">
AND company_name=#{companyName}
</if>
<if test="status !=null ">
AND status=#{status}
</if>
</where>
</select>
2.3 choose
<select id="findBrandByCondition3" resultMap="brandMap">
SELECT
id,
brand_name,
company_name,
ordered,
description,
status
FROM tb_brand
<where>
<choose>
<when test="brandname!=null">
brand_name=#{brandname}
</when>
<when test="companyname!=null">
company_name=#{companyname}
</when>
<when test="status!=null">
status=#{status}
</when>
</choose>
</where>
</select>
2.4添加
xml:
<insert id="addBrand" parameterType="com.itheima.pojo.Brand">
insert into tb_brand (brand_name, company_name, ordered, description, status)
values (#{brandName}, #{companyName}, #{ordered}, #{description}, #{status})
</insert>
接口：
/**
* 添加品牌
* @param brand 品牌对象
* @return 受影响的行数
*/
public int addBrand(Brand brand);
测试代码：
@Test
public void testAddBrand(){
//使用SqlSessionFactory工厂类，创建SqlSession
SqlSession sqlSession = MybatisUtil.openSession();
//利用sqlSession，创建一个代理对象
BrandMapper sessionMapper = sqlSession.getMapper(BrandMapper.class);
Brand brand=new Brand();
brand.setStatus(1);
brand.setBrandName("测试1");
brand.setCompanyName("测试1");
brand.setDescription("测试1");
brand.setOrdered(5);
//插入数据
int rowCount=sessionMapper.addBrand(brand);
if(rowCount>0){
System.out.println("插入数据成功");
}
//释放资源
MybatisUtil.closeSqlSession(sqlSession);
}
2.5添加-主键返回
在mybatis的insert操作过程中，存在一各路扶桑 术：主键回填，在向表中插入 一行记录后，会自动把当前行的主键列下的数据值获取
2.5.1SQL
CREATE TABLE tb_order(
id int primary key auto_increment,
payment double,
payment_type int,
status int
);
create table tb_order_item
(
id int primary key auto_increment,
goods_name varchar(20),
goods_price double,
count varchar(32),
order_id int
);
insert into tb_order(payment,payment_type,status)values(4887,1,2),(1975,1,1);
insert into tb_order_item(goods_name,goods_price,count,order_id)values('华为手机',3888,1,1),('华为Pad',999,1,1),('小米手机',888,2,2),('小米手环',199,1,2);
2.5.2pojo
package com.itheima.pojo;
public class Order {
private Integer id;
private Double payment;
private Integer paymentType;
private Integer status;
public Order() {
}
public Order(Integer id, Double payment, Integer paymentType, Integer status) {
this.id = id;
this.payment = payment;
this.paymentType = paymentType;
this.status = status;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Double getPayment() {
return payment;
}
public void setPayment(Double payment) {
this.payment = payment;
}
public Integer getPaymentType() {
return paymentType;
}
public void setPaymentType(Integer paymentType) {
this.paymentType = paymentType;
}
public Integer getStatus() {
return status;
}
public void setStatus(Integer status) {
this.status = status;
}
@Override
public String toString() {
return "Order{" +
"id=" + id +
", payment=" + payment +
", paymentType=" + paymentType +
", status=" + status +
'}';
}
}
package com.itheima.pojo;
public class OrderItem {
private Integer id;
private String goodsName;
private double goodsPrice;
private String count;
private Integer orderId;
public OrderItem() {
}
public OrderItem(Integer id, String goodsName, double goodsPrice, String count, Integer orderId) {
this.id = id;
this.goodsName = goodsName;
this.goodsPrice = goodsPrice;
this.count = count;
this.orderId = orderId;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getGoodsName() {
return goodsName;
}
public void setGoodsName(String goodsName) {
this.goodsName = goodsName;
}
public double getGoodsPrice() {
return goodsPrice;
}
public void setGoodsPrice(double goodsPrice) {
this.goodsPrice = goodsPrice;
}
public String getCount() {
return count;
}
public void setCount(String count) {
this.count = count;
}
public Integer getOrderId() {
return orderId;
}
public void setOrderId(Integer orderId) {
this.orderId = orderId;
}
@Override
public String toString() {
return "OrderItem{" +
"id=" + id +
", goodsName='" + goodsName + '\'' +
", goodsPrice=" + goodsPrice +
", count='" + count + '\'' +
", orderId=" + orderId +
'}';
}
}
2.5.3orderMapper.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">
<!--利用namespace属性，绑定当前映射文件和mapper接口映射关联-->
<mapper namespace="com.itheima.dao.OrderMapper">
<!--添加订单-->
<insert id="addOrder" parameterType="com.itheima.pojo.Order" useGeneratedKeys="true" keyProperty="id">
insert into tb_order(payment,payment_type,status)
values(#{payment},#{paymentType},#{status})
</insert>
<!--添加订单明细-->
<insert id="addOrderItem" parameterType="com.itheima.pojo.OrderItem">
insert into tb_order_item(goods_name,goods_price,count,order_id)
values(#{goodsName},#{goodsPrice},#{count},#{orderId})
</insert>
</mapper>
2.5.4orderMapper接口
package com.itheima.dao;
import com.itheima.pojo.Order;
import com.itheima.pojo.OrderItem;
public interface OrderMapper {
/**
* 添加订单
* @param order 订单对象
* @return 返行行数
*/
public int addOrder(Order order);
/**
* 添加订单明细
* @param orderItem 订单明细对象
* @return 返回行数
*/
public int addOrderItem(OrderItem orderItem);
}
测试代码：
package com.itheima.test;
import com.itheima.dao.BrandMapper;
import com.itheima.dao.OrderMapper;
import com.itheima.pojo.Order;
import com.itheima.pojo.OrderItem;
import com.itheima.utils.MybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
public class OrderMapperTest {
@Test
public void TestAddOrder(){
//使用SqlSessionFactory工厂类，创建SqlSession
SqlSession sqlSession = MybatisUtil.openSession();
//利用sqlSession，创建一个代理对象
OrderMapper orderMapper = sqlSession.getMapper(OrderMapper.class);
Order order=new Order();
order.setPayment(10000.0);
order.setPaymentType(2); //2表示支付宝
order.setStatus(1);
int rowCount = orderMapper.addOrder(order);
//订单对象
OrderItem orderItem=new OrderItem();
orderItem.setOrderId(order.getId());
orderItem.setGoodsName("小米");
orderItem.setGoodsPrice(1000);
orderItem.setCount("10");
int count2=orderMapper.addOrderItem(orderItem);
if(rowCount>0 && count2>0){
sqlSession.commit();
System.out.println("插入数据成功");
}
//释放资源
MybatisUtil.closeSqlSession(sqlSession);
}
}
2.6修改所有字段
brandMapper.xml
<update id="updateBrand">
update tb_brand
set brand_name=#{brandName},
company_name=#{companyName},
ordered=#{ordered},
description=#{description},
status=#{status}
where id=#{id}
</update>
2.7修改部份数据
brandMapper.xml
<!--修改数据-->
<update id="updateBrand">
update tb_brand
<set>
<if test="brandName!=null">
brand_name=#{brandName}
</if>
<if test="companyName!=null">
company_name=#{companyName}
</if>
<if test="ordered!=null">
ordered=#{ordered},
</if>
<if test="description!=null">
description=#{description}
</if>
<if test="status!=null">
status=#{status}
</if>
</set>
where id=#{id}
</update>
brandMapper接口
/**
* 修改品牌
* @param brand 品牌对象
* @return 受影响的行数
*/
public int updateBrand(Brand brand);
测试代码
@Test
public void testUpdateBrand(){
//使用SqlSessionFactory工厂类，创建SqlSession
SqlSession sqlSession = MybatisUtil.openSession();
//利用sqlSession，创建一个代理对象
BrandMapper sessionMapper = sqlSession.getMapper(BrandMapper.class);
Brand brand=new Brand();
brand.setStatus(1);
brand.setBrandName("苹果");
brand.setCompanyName("苹果股份");
brand.setDescription("好用");
brand.setOrdered(9);
brand.setId(3);
//插入数据
int rowCount=sessionMapper.updateBrand(brand);
if(rowCount>0){
sqlSession.commit();
System.out.println("修改数据成功");
}
//释放资源
MybatisUtil.closeSqlSession(sqlSession);
}
2.8批量删除-动态SQL
brandMapper.xml
<delete id="deleteByIds">
delete from tb_brand where id
in(
<foreach collection="ids" item="id" separator=",">
#{id}
</foreach>
);
</delete>
brandMapper接口
/**
* 批量删除品牌
* @param ids
* @return
*/
public int deleteByIds(@Param("ids") List<Integer>ids);
测试代码
@Test
public void testDeleteBrandByIds(){
//使用SqlSessionFactory工厂类，创建SqlSession
SqlSession sqlSession = MybatisUtil.openSession();
//利用sqlSession，创建一个代理对象
BrandMapper sessionMapper = sqlSession.getMapper(BrandMapper.class);
List<Integer> ids=new ArrayList<>();
Collections.addAll(ids,1,2,3);
int count=sessionMapper.deleteByIds(ids);
if(count>0){
sqlSession.commit();
System.out.println("删除成功");
}
//释放资源
MybatisUtil.closeSqlSession(sqlSession);
}
