package com.jero.pojo3;
<?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">
<!-- 映射文件 -->
<mapper namespace="com.jero.pojo3">
<!-- 结果集映射的配置标签
属性说明 id属性 ,resultMap标签的标识。
type属性 ,返回值的全限定类名,或类型别名。
autoMapping属性 ,值范围true(默认值)|false, 设置是否启动自动映射功能,
自动映射功能就是自动查找与字段名小写同名的属性名,
并调用setter方法。而设置为false后,
则需要在resultMap内明确注明映射关系才会调用对应的setter方法。 -->
<resultMap type="Product" id="productBean">
<id column="pid" property="id"/>
<result column="pname" property="name"/>
<result column="price" property="price"/>
<!-- 多对一的关系 -->
<!-- property: 指的是属性名称, javaType:指的是属性的类型 -->
<association property="category" javaType="Category">
<id column="cid" property="id"/>
<result column="cname" property="name"/>
</association>
</resultMap>
<!-- 根据id查询Product, 关联将Orders查询出来 -->
<select id="listProduct" resultMap="productBean">
select c.*, p.*, c.id 'cid', p.id 'pid', c.name 'cname', p.name 'pname' from category_ c left join product_ p on c.id = p.cid
</select>
<!-- 根据名称模糊查询 只查出名称对应的数据 -->
<select id="listProductByName" resultMap="productBean">
select * from product_ where name like concat('%',#{name},'%')
</select>
</mapper>
<?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">
<!-- 配置的意思 -->
<configuration>
<!-- 写实体类的别名,,写了之后可以在写Sql配置文件
例如<select>标签中的属性就可以不用写实体的具体路径直接用别名就可以了 -->
<typeAliases>
<package name="com.jero.pojo3"/>
</typeAliases>
<!-- 环境配置的标签,配置连接数据库所需的属性值 -->
<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://localhost:3306/how2java?characterEncoding=UTF-8"/>
<property name="username" value="root"/>
<property name="password" value=""/>
</dataSource>
</environment>
</environments>
<!-- 配置映射的文件 -->
<mappers>
<mapper resource="com/jero/pojo3/Category.xml"/>
<mapper resource="com/jero/pojo3/Product.xml"/>
</mappers>
</configuration>
public class Product {private int id;private String name;private float price;private Category category;public Category getCategory() {return category;}public void setCategory(Category category) {this.category = category;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public float getPrice() {return price;}public void setPrice(float price) {this.price = price;}@Overridepublic String toString() {return "Product [id=" + id + ", name=" + name + ", price=" + price+ "]";}}
package com.jero.pojo3;
import java.util.List;
public class Category {
private int id;
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "Category [id=" + id + ", name=" + name + "]";
}
}
package com.jero.pojo3;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class Test {
public static void main(String[] args){
//资源文件
String resource = "mybatis-config3.xml";
try {
//输入流,传入配置好的文件
InputStream inputStream = Resources.getResourceAsStream(resource);
//创建sql工厂,让配置好的文件成为一个sql工厂
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//开启此工厂
SqlSession sqlSession = sessionFactory.openSession();
System.out.println("精确查询:");
//获取Product的数据,并存进集合
List<Product> products = sqlSession.selectList("listProduct");
//遍历并打印
for (Product product : products) {
System.out.println(product+"product的分类是:"+product.getCategory());
}
System.out.println("模糊查询:");
//将要查询的字段和字段值存进一个集合映射
Map<String,Object> params = new HashMap();
params.put("name","b");
//将通过模糊查询得到的数据存进集合
List<Product> products2 = sqlSession.selectList("listProductByName",params);
for (Product p : products2) {
System.out.println(p);
}
sqlSession.commit();
sqlSession.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
<?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="com.jero.pojo3">
<resultMap type="Category" id="categoryBean">
<id column="cid" property="id" />
<result column="cname" property="name" />
<!-- 一对多的关系 -->
<!-- property: 指的是集合属性的值, ofType:指的是集合中元素的类型 -->
<collection property="products" ofType="Product">
<id column="pid" property="id" />
<result column="pname" property="name" />
<result column="price" property="price" />
</collection>
</resultMap>
<!-- 关联查询分类和产品表 -->
<select id="listCategory" resultMap="categoryBean">
select c.*, p.*, c.id 'cid', p.id 'pid', c.name 'cname', p.name 'pname' from category_ c left join product_ p on c.id = p.cid
</select>
</mapper>