字段名与实体类属性不匹配（[尚硅谷]_张晓飞_Mybatis 学习笔记二）
创建表CREATE TABLE orders(
order_id INT PRIMARY KEY AUTO_INCREMENT,
order_no VARCHAR(20),
order_price FLOAT
);
INSERT INTO orders(order_no, order_price) VALUES('aaaa', 23);
INSERT INTO orders(order_no, order_price) VALUES('bbbb', 33);
INSERT INTO orders(order_no, order_price) VALUES('cccc', 22);
创建javabean类
package com.hb.bean;
public class Order {
private int id;
private String orderNo;
private float price;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getOrderNo() {
return orderNo;
}
public void setOrderNo(String orderNo) {
this.orderNo = orderNo;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
@Override
public String toString() {
return "Order ";
}
}
创建映射XML文件
<?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.hb.bean.orderMapper">
<!-- 这里namespace必须是“包名 + xml文件名”，不然要运行的时候要报错 “is not known to the MapperRegistry” -->
<!-- 在SQL语句中定义别名，保证别名与类属性名一致 -->
<select id="selectOrder" parameterType="int" resultType="com.hb.bean.Order">
select
order_id id, order_no orderNo,order_price price from orders where
order_id=#{id}
</select>
<!-- 使用自定义类型，指名类属性与表字段的对应关系 -->
<select id="selectOrderResultMap" parameterType="int" resultMap="orderResultMap">
select * from orders where order_id=#{id}
</select>
<resultMap type="com.hb.bean.Order" id="orderResultMap">
<id property="id" column="order_id" />
<result property="orderNo" column="order_no" />
<result property="price" column="order_price" />
</resultMap>
</mapper>
配置mybatis总配置文件
<?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">
<configuration>
<settings>
<!-- changes from the defaults for testing -->
<setting name="cacheEnabled" value="false" />
<setting name="useGeneratedKeys" value="true" />
<setting name="defaultExecutorType" value="REUSE" />
</settings>
<environments default="development">
<environment id="development">
<transactionManager type="jdbc" />
<dataSource type="POOLED">
<!--
<property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
<property name="url" value="jdbc:oracle:thin:@192.168.56.201:1521:system"/>
-->
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/mybatis" />
<property name="username" value="root" />
<property name="password" value="123456" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/hb/bean/orderMapper.xml" />
</mappers>
</configuration>
创建测试类
package com.hb.test2;
import java.io.InputStream;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;
import com.hb.bean.Order;
public class Test2 {
public static SqlSessionFactory sqlSessionFactory;
public static SqlSession sqlSession;
@Before
public void init(){
//"/"表示是在src根目录下
String source = "config.xml";
InputStream inputStream = Test2.class.getClassLoader().getResourceAsStream(source);
try {
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//sqlSession = sqlSessionFactory.openSession();
//是否自动提交，默认不是自动提交的
sqlSession = sqlSessionFactory.openSession(true);
} catch (Exception e) {
e.printStackTrace();
}
}
@Test
public void selectById(){
String statment = "com.hb.bean.orderMapper.selectOrder";
Order order = sqlSession.selectOne(statment, 1);
System.out.println(order);
}
@Test
public void selectById2(){
String statment = "com.hb.bean.orderMapper.selectOrderResultMap";
Order order = sqlSession.selectOne(statment, 1);
System.out.println(order);
}
}
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