mybatis_day02
2.映射器Mapper
相当于dao层,不用写实现类(mybatis底层会采用动态代理模式 会跟我生成实现)
步骤：
(1) 创建项目 配置mybatis-config.xml 和昨天一样
(2) 创建接口 ProductMapper (XXXXMapper) 里面定义一个方法findAll -->以前dao层/mapper层
(3) 在对应的ProductMapper.xml namespace 和
标签里面id (namespace+id) == (ProductMapper包路径+方法)
<select id="findAll" resultType="product">
select * from product
</select>
3.高级查询
3.1 like查询
方式一(存在sql注入的问题)：
<if test="productName != null">
and productName like '%${productName}%'
</if>
方式二：
<if test="productName != null">
and productName like concat('%',#{productName},'%')
</if>
3.2特殊符号转译
方式一：
Eq： <if test="minPrice != null and maxPrice != null">
and salePrice > #{minPrice} and salePrice < #{maxPrice}
</if>
方式二(CDATA)：
<![CDATA[ ]]>
Eq:<if test="minPrice != null and maxPrice != null">
<![CDATA[
and salePrice > #{minPrice} and salePrice <= #{maxPrice}
]]>
</if>
4.结果映射
处理表字段和domain的对象字段不一致的情况
4.1 使用别名
<select id="findAll" resultType="product">
select id,productName pName,salePrice,costPrice,cutoff from product
</select>
4.2 返回Map解决
<select id="findAll" resultMap="productMap">
select id,productName,salePrice,costPrice,cutoff from product
</select>
<resultMap id="productMap" type="product">
<!-- id:主键
property:类里面的属性
column:查询列名称
-->
<id property="id" column="id"></id>
<result property="pName" column="productName"></result>
<result property="salePrice" column="salePrice"></result>
</resultMap>
5.关系处理
5.1 对一方处理
嵌套结果: 只发送一条sql
嵌套查询: 发送 1+n条sql
<?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="cn.itsource._03_manytoone.mapper.ProductMapper">
<!-- <resultMap id="productMap" type="product">
<id column="id" property="id"></id>
<result column="productName" property="pName"></result>
<result column="salePrice" property="salePrice"></result>
<result column="costPrice" property="costPrice"></result>
<result column="cutoff" property="cutoff"></result>
<!– 处理一方–>
<association property="dir" javaType="productDir">
<id column="did" property="id"></id>
<result column="dname" property="dirName"></result>
</association>
</resultMap>-->
<!-- (1)嵌套结果 发送一条sql语句-->
<!-- <select id="findAll" resultMap="productMap">
SELECT p.id, p.productName, p.salePrice, p.costPrice, p.cutoff, dir.id did, dir.dirName dname
FROM
product p
JOIN productDir dir ON p.dir_id = dir.id
</select>-->
<!-- 嵌套查询:发送多sql语句(1+n条sql)-->
<select id="findAll" resultMap="productMap">
SELECT
p.id,p.productName,p.salePrice, p.costPrice,p.cutoff,p.dir_id
FROM product p
</select>
<resultMap id="productMap" type="product">
<id column="id" property="id"></id>
<result column="productName" property="pName"></result>
<result column="salePrice" property="salePrice"></result>
<result column="costPrice" property="costPrice"></result>
<result column="cutoff" property="cutoff"></result>
<!--根据上面查询dir_id 在去查询 分类对象-->
<association property="dir" column="dir_id" javaType="productDir" select="selectDir">
</association>
</resultMap>
<select id="selectDir" parameterType="long" resultType="ProductDir">
select * from productDir where id = #{dir_id}
</select>
</mapper>
5.2 对多方进行处理
嵌套结果和嵌套查询
<?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="cn.itsource._04_onetomany.mapper.ProductDirMapper">
<!-- 嵌套结果-->
<!-- <select id="findAll" resultMap="productDirMap">
select dir.id ,dir.dirName,
p.id pid,p.productName pName,p.salePrice,p.costPrice,p.cutoff
from productDir dir join product p
on dir.id = p.dir_id
</select>
<resultMap id="productDirMap" type="productDir">
<id property="id" column="id"></id>
<result property="dirName" column="dirName"></result>
<collection property="products" ofType="product">
<id property="id" column="pid"></id>
<result property="pName" column="pName"></result>
<result property="salePrice" column="salePrice"></result>
<result property="costPrice" column="costPrice"></result>
</collection>
</resultMap>-->
<!-- 嵌套查询-->
<select id="findAll" resultMap="productDirMap">
select dir.id ,dir.dirName from productDir dir
</select>
<resultMap id="productDirMap" type="productDir">
<id property="id" column="id"></id>
<result property="dirName" column="dirName"></result>
<collection property="products" column="id" ofType="product" select="selectProducts">
</collection>
</resultMap>
<select id="selectProducts" parameterType="long" resultType="product">
select id,productName pName,salePrice,costPrice,cutoff
from product where dir_id = #{dir_id}
</select>
</mapper>
6.SSM整合
6.1 整合步骤
(1)创建项目--web项目 (maven/普通web)
(2)导入三个框架的jar包
(3)配置文件
applicationContext.xml --配置spring+mybatis
<!--sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"></property>
<property name="mapperLocations" value="classpath:cn/itsource/ssm/mapper/*Mapper.xml"></property>
<property name="typeAliasesPackage">
<value>
cn.itsource.ssm.domain
</value>
</property>
</bean>
<!-- 把产生mapper 交给 spring-->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="cn.itsource.ssm.mapper"></property>
</bean>
