MyBatis实现对数据库的增删改查
Posted 鹤城
tags:
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首先，整个项目的结构如图：
本次主要是对tb_brand表实现增删改查。
创建先后顺序
创建的先后顺序我在前一篇博客已经说清楚了，就不再赘述了，如果不知道如何创建的话，说明对mybatis还是不了解，建立仔细看一看上一篇博客，这是链接：一篇博客带你学会MyBatis
Brand实体类
package com.itheima.pojo;
public class Brand
private Integer id;
private String brandName;
private String companyName;
private Integer ordered;
private String description;
private Integer 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;
@Override
public String toString()
return "Brand" +
"id=" + id +
", brandName=\'" + brandName + \'\\\'\' +
", companyName=\'" + companyName + \'\\\'\' +
", ordered=" + ordered +
", description=\'" + description + \'\\\'\' +
", status=" + status +
\'\';
public Integer getStatus()
return status;
public void setStatus(Integer status)
this.status = status;
mapper接口
package com.itheima.mapper;
import com.itheima.pojo.Brand;
import org.apache.ibatis.annotations.Param;
import java.util.List;
import java.util.Map;
public interface BrandMapper
/**
* 查询所有
*/
public List<Brand> selectAll();
/**
* 查看详情：根据id查询
*/
Brand selectById(int id);
/**
* 条件查询
* * 参数接收
* 1.散装对象 如果方法中有多个参数，需使用@Param("sql占位符名称")
* 2.封装对象
* 3.map集合参数
*
*/
//List<Brand> selectByCondition(@Param("status") int status, @Param("companyName") String companyName, @Param("brandName") String brandName);
//List<Brand> selectByCondition(Brand brand);
List<Brand> selectByCondition(Map map);
/**
* 单条件动态查询
* @param brand
* @return
*/
List<Brand> selectByConditionSingle(Brand brand);
/**
* 添加
*/
void add(Brand brand);
/**
* 修改功能
*/
int update(Brand brand);
/**
* 根据id删除
*/
void delById(int id);
/**
* 批量删除
*/
void delByIds(@Param("ids") int[] ids);
sql映射文件
<?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">
<!--
namespace: 名称空间
-->
<mapper namespace="com.itheima.mapper.BrandMapper">
<!--
数据库表的字段名称 和 实体类的属性名称不一样，则不能自动封装
*起别名：对不一样的列名起别名，让别名和实体类的属性名一样
*缺点:每次查询都要定义一次别名
*解决:使用sql片段（但还是不灵活）
*resultMap：
1. 定义<resulMap>标签
2. 在<select>标签中使用resulMap属性替换resultType属性
-->
<!--
sql片段
-->
<!-- <sql id="brand_cloumn">id, brand_name as brandName, company_name as companyName, ordered, description, status</sql>-->
<!-- <select id="selectAll" resultType="brand">-->
<!-- select-->
<!-- <include refid="brand_cloumn"></include>-->
<!-- from tb_brand;-->
<!-- </select>-->
<!-- id:唯一标识 type：映射的类型，支持别名 -->
<resultMap id="brandResultMap" type="brand">
<!-- id:完成主键字段的映射 result：完成一般字段的映射 -->
<result column="brand_name" property="brandName"></result>
<result column="company_name" property="companyName"></result>
</resultMap>
<select id="selectAll" resultMap="brandResultMap">
select * from tb_brand;
</select>
<!--
*参数占位符：
1. # 会将其替换成?，用来防止sql注入
2. $ 拼sql，会存在sql注入问题
3. 使用时机：
*参数传递的时候：#
*表名或列名不固定的情况下：$(会存在sql注入)
*参数类型 ：parameterType：可以省略
*特殊字符的处理：
1.转义字符
2.CDATA区 <![CDATA[ 内容 ]]>
-->
<select id="selectById" resultMap="brandResultMap">
select *
from tb_brand where id < #id;
</select>
<!-- <select id="selectById" resultMap="brandResultMap">-->
<!-- select *-->
<!-- from tb_brand where id = #id;-->
<!-- </select>-->
<!-- 条件查询 -->
<!-- <select id="selectByCondition" resultMap="brandResultMap">-->
<!-- select *-->
<!-- from tb_brand-->
<!-- where-->
<!-- status = #status-->
<!-- and company_name like #companyName-->
<!-- and brand_name like #brandName-->
<!-- </select>-->
<!--
动态条件查询
*if:条件判断
*test：逻辑表达式
*问题
*恒等式
*<where> 替换 where关键字
-->
<select id="selectByCondition" resultMap="brandResultMap">
select *
from tb_brand
/*where 1 = 1*/
<where>
<if test="status != null">
and status = #status
</if>
<if test="companyName != null and companyName != \'\' ">
and company_name like #companyName
</if>
<if test="brandName != null and brandName != \'\' ">
and brand_name like #brandName
</if>
</where>
</select>
<select id="selectByConditionSingle" resultMap="brandResultMap">
select *
from tb_brand
<where>
<choose><!-- 相当于switch -->
<when test="status != null"><!-- 相当于case -->
status = #status
</when>
<when test="companyName != null and companyName != \'\' ">
company_name like #companyName
</when>
<when test="brandName != null and brandName != \'\' ">
brand_name like #brandName
</when>
<!-- <otherwise>-->
<!-- 1 = 1-->
<!-- </otherwise>-->
</choose>
</where>
</select>
<insert id="add" useGeneratedKeys="true" keyProperty="id">
insert into tb_brand (brand_name,company_name,ordered,description,status)
values (#brandName,#companyName,#ordered,#description,#status);
</insert>
<update id="update">
update tb_brand
<set>
<if test="brandName != null and brandName != \'\'">
brand_name = #brandName,
</if>
<if test="companyName != null and companyName != \'\'">
company_name = #companyName,
</if>
<if test="ordered != null">
ordered = #ordered,
</if>
<if test="description != null and description != \'\' ">
description = #description,
</if>
<if test="status != null">
status = #status
</if>
</set>
where id = #id;
</update>
<delete id="delById">
delete from tb_brand where id = #id;
</delete>
<!-- mybatis会将数组参数，封装成一个map集合
*默认： array = 数组
*使用@Param参数注解改变map集合key的名称
-->
<delete id="delByIds">
delete from tb_brand where id
in <foreach collection="ids" item="id" separator="," open="(" close=")">
#id
</foreach>
</delete>
</mapper>
核心配置文件
<?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>
<setting name="logImpl" value="STDOUT_LOGGING" />
</settings>
<!-- 别名,UserMapper.xml文件中resultType属性就可以写pojo下的类名（类名还可以不区分大小写） -->
<typeAliases>
<package name="com.itheima.pojo"/>
</typeAliases>
<!--
environments：配置数据库链接环境信息，可以配置多个environment，通过切换default属性切换不同的environment
-->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<!-- 数据库链接信息 -->
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
<environment id="test">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<!-- 数据库链接信息 -->
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<mappers>
<!-- 加载sql映射文件 -->
<!-- <mapper resource="com/itheima/mapper/UserMapper.xml"/>-->
<!-- mapper代理方式 -->
<package name="com.itheima.mapper"/>
</mappers>
</configuration>
执行sql完成增删改查
package com.itheima.test;
import com.itheima.mapper.BrandMapper;
import com.itheima.pojo.Brand;
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.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MyBatisTest
@Test
public void testSelectAll() throws IOException
//1. 获取sqlsessionFactory
//1. 加载MyBatis配置文件，获取SqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//2. 获取SqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//3. 获取Mapper接口的代理对象
BrandMapper brandmapper = sqlSession.getMapper(BrandMapper.class);
//4. 执行方法
List<Brand> brands = brandmapper.selectAll();
System.out.println(brands);
//5. 释放资源
sqlSession.close();
@Test
public void testSelectByid() throws IOException
//接收参数
int id = 1;
//1. 获取sqlsessionFactory
//1. 加载MyBatis配置文件，获取SqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//2. 获取SqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//3. 获取Mapper接口的代理对象
BrandMapper brandmapper = sqlSession.getMapper(BrandMapper.class);
//4. 执行方法
Brand brand = brandmapper.selectById(id);
System.out.println(brand);
//5. 释放资源
sqlSession.close();
@Test
public void testSelectByCondition() throws IOException
//接收参数
int status = 1;
String companyName = "华为";
String brandName = "华为";
//处理参数
companyName = "%"+companyName+"%";
brandName = "%"+brandName+"%";
//封装对象
/*Brand brand = new Brand();
brand.setStatus(status);
brand.setCompanyName(companyName);
brand.setBrandName(brandName);*/
Map map = new HashMap();
//map.put("status",status);
//map.put("companyName",companyName);
map.put("brandName",brandName);
//1. 获取sqlsessionFactory
//1. 加载MyBatis配置文件，获取SqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//2. 获取SqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//3. 获取Mapper接口的代理对象
BrandMapper brandmapper = sqlSession.getMapper(BrandMapper.class);
//4. 执行方法
//List<Brand> brands = brandmapper.selectByCondition(status, companyName, brandName);
//List<Brand> brands = brandmapper.selectByCondition(brand);
List<Brand> brands = brandmapper.selectByCondition(map);
System.out.println(brands);
//5. 释放资源
sqlSession.close();
@Test
public void testSelectByConditionSingle() throws IOException
//接收参数
int status = 1;
String companyName = "华为";
String brandName = "华为";
//处理参数
companyName = "%"+companyName+"%";
brandName = "%"+brandName+"%";
//封装对象
Brand brand = new Brand();
//brand.setStatus(status);
//brand.setCompanyName(companyName);
//brand.setBrandName(brandName);
//1. 获取sqlsessionFactory
//1. 加载MyBatis配置文件，获取SqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//2. 获取SqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//3. 获取Mapper接口的代理对象
BrandMapper brandmapper = sqlSession.getMapper(BrandMapper.class);
//4. 执行方法
//List<Brand> brands = brandmapper.selectByCondition(status, companyName, brandName);
//List<Brand> brands = brandmapper.selectByCondition(brand);
List<Brand> brands = brandmapper.selectByConditionSingle(brand);
System.out.println(brands);
//5. 释放资源
sqlSession.close();
@Test
public void testAdd() throws IOException
//接收参数
int status = 1;
String companyName = "波导手机2";
String brandName = "波导2";
String description = "手机中的战斗机";
int ordered = 100;
//封装对象
Brand brand = new Brand();
brand.setStatus(status);
brand.setCompanyName(companyName);
brand.setBrandName(brandName);
brand.setDescription(description);
brand.setOrdered(ordered);
//1. 获取sqlsessionFactory
//1. 加载MyBatis配置文件，获取SqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//2. 获取SqlSession对象
//SqlSession sqlSession = sqlSessionFactory.openSession();
SqlSession sqlSession = sqlSessionFactory.openSession(true);
//3. 获取Mapper接口的代理对象
BrandMapper brandmapper = sqlSession.getMapper(BrandMapper.class);
//4. 执行方法
brandmapper.add(brand);
Integer id = brand.getId();
System.out.println(id);
//提交事务
//sqlSession.commit();
//5. 释放资源
sqlSession.close();
@Test
public void testUpdate() throws IOException
//接收参数
int status = 0;
String companyName = "波导手机";
String brandName = "波导";
String description = "波导手机,手机中的战斗机";
int ordered = 200;
int id = 6;
//封装对象
Brand brand = new Brand();
brand.setStatus(status);
//brand.setCompanyName(companyName);
//brand.setBrandName(brandName);
//brand.setDescription(description);
//brand.setOrdered(ordered);
brand.setId(id);
//1. 获取sqlsessionFactory
//1. 加载MyBatis配置文件，获取SqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//2. 获取SqlSession对象
//SqlSession sqlSession = sqlSessionFactory.openSession();
SqlSession sqlSession = sqlSessionFactory.openSession();
//3. 获取Mapper接口的代理对象
BrandMapper brandmapper = sqlSession.getMapper(BrandMapper.class);
//4. 执行方法
int count = brandmapper.update(brand);
System.out.println(count);
//提交事务
sqlSession.commit();
//5. 释放资源
sqlSession.close();
@Test
public void testDelById() throws IOException
//接收参数
int id = 6;
//1. 获取sqlsessionFactory
//1. 加载MyBatis配置文件，获取SqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//2. 获取SqlSession对象
//SqlSession sqlSession = sqlSessionFactory.openSession();
SqlSession sqlSession = sqlSessionFactory.openSession();
//3. 获取Mapper接口的代理对象
BrandMapper brandmapper = sqlSession.getMapper(BrandMapper.class);
//4. 执行方法
brandmapper.delById(id);
//提交事务
sqlSession.commit();
//5. 释放资源
sqlSession.close();
@Test
public void testDelByIds() throws IOException
//接收参数
int[] ids = 6,7;
//1. 获取sqlsessionFactory
//1. 加载MyBatis配置文件，获取SqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//2. 获取SqlSession对象
//SqlSession sqlSession = sqlSessionFactory.openSession();
SqlSession sqlSession = sqlSessionFactory.openSession();
//3. 获取Mapper接口的代理对象
BrandMapper brandmapper = sqlSession.getMapper(BrandMapper.class);
//4. 执行方法
brandmapper.delByIds(ids);
//提交事务
sqlSession.commit();
//5. 释放资源
sqlSession.close();
maven配置文件
<?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>org.example</groupId>
<artifactId>mybatis-demo</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<!-- mybatis的依赖 -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.5</version>
</dependency>
<!-- mysql驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>
<!-- junit单元测试 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.1</version>
<scope>test</scope>
</dependency>
<!-- 添加slf4j日志api -->
<!-- <dependency>-->
<!-- <groupId>org.slf4j</groupId>-->
<!-- <artifactId>slf4j-log4j12</artifactId>-->
<!-- <version>1.7.19</version>-->
<!-- </dependency>-->
</dependencies>
</project>
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