mybatis
依赖
<dependencies>
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.6</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.20</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.2</version>
<scope>test</scope>
</dependency>
</dependencies>
<!-- 插件-->
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>11</source>
<target>11</target>
</configuration>
</plugin>
</plugins>
</build>配置XML
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/demo?characterEncoding=utf8
jdbc.username=root
jdbc.password=123456
<?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>
<!-- 引入配置文件-->
<properties resource="properties/db.properties"></properties>
<!-- 别名-->
<typeAliases>
<package name="com.pojo"/>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<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>
</environments>
<!-- 配置映射文件-->
<mappers>
<mapper resource="mappers/HouseingTypeMapper.xml"></mapper>
</mappers>
</configuration>pojo实体类
package com.pojo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class HouseingType {
private Integer typeId;
private String typename;
}映射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">
<mapper namespace="HouseingTypeMapper">
<select id="selectHouseingType" resultType="HouseingType">
select * from housingtype
</select>
</mapper>工具类
#properties/config.properties
mybatisConfig=mybatisConfig.xml
package com.Utils;
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 java.io.IOException;
import java.io.InputStream;
public class MybatisUtils {
public static SqlSession getSqlSession() throws IOException {
// 读取配置文件
Properties pro = new Properties();
pro.load(MybatisUtils.class.getClassLoader().getResourceAsStream("properties/config.properties"));
String configFileName = String.valueOf(pro.get("mybatisConfig"));
InputStream inputStream = Resources.getResourceAsStream(configFileName);
// 创建sessionFactory
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
// 返回sqlSession对象
return sessionFactory.openSession(true); // 设置true自动提交事务
}
}Junit
#插件 JUnitGenerator V2.0
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.2</version>
<scope>test</scope>
</dependency>
增删改查
<?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="HouseingTypeMapper">
<!-- 无条件查询-->
<select id="selectHouseingType" resultType="HouseingType">
select * from housingtype;
</select>
<!--单条件查询-->
<select id="conditionHouseingType" parameterType="java.lang.Integer" resultType="HouseingType">
select * from housingtype where typeId = #{typeId};
</select>
<!-- 多条件查询-->
<select id="multipleConditionsHouseingType" resultType="HouseingType">
select * from housingtype where typeId in
<foreach collection="array" item="num" open="(" separator="," close=")">
#{num}
</foreach>
</select>
<!--模糊查询-->
<select id="fuzzyselectHouseingType" parameterType="java.lang.String" resultType="HouseingType">
select * from housingtype where typename like "%${value}%";
</select>
<!--插入数据-->
<insert id="insertHouseingType" parameterType="HouseingType">
insert into housingType values (#{typeId},#{typename});
</insert>
<!--删除数据-->
<delete id="delHouseingType" parameterType="java.lang.Integer">
delete from housingType where typeId = #{typeId};
</delete>
<!-- 批量删除-->
<delete id="multipleConditionsDelHouseingType" parameterType="CheckRecordVo">
delete from checkhouserecord where cId in
<foreach collection="array" item="n" open="(" separator="," close=")">
#{n}
</foreach>
</delete>
<!--修改数据-->
<update id="editHouseingType" parameterType="HouseingType">
update housingType set typename=#{typename} where typeId=#{typeId};
</update>
</mapper>
<foreach>
<?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.mybatis_demo.mapper.UserMapper">
<!-- 遍历list集合，collection="list"，如果你传参的时候是直接传递list集合，那么这里只能填list,不能填参数名 -->
<select id="selectByList" resultType="User">
select * from t_user where uid in
<foreach collection="list" item="item" open="(" separator="," close=")">
#{item}
</foreach>
</select>
<!-- 遍历数组 ，collection="array"，如果你传参的时候是直接传递数组，那么这里只能填array,不能填参数名-->
<select id="selectByArray" resultType="User">
select * from t_user where uid in
<foreach collection="array" item="item" open="(" separator="," close=")">
#{item}
</foreach>
</select>
<!-- 遍历包装类中的数组，collection="ids"，这里不再是array,而是包装类中对应的变量名，因为你传递的参数是一个包装类，mybatis是通过get方法获取包装类中的数组 -->
<select id="selectUserVoByArray" parameterType="UserVo" resultType="User">
select * from t_user where uid in
<foreach collection="ids" item="item" open="(" separator="," close=")">
#{item}
</foreach>
</select>
<!-- 遍历包装类中的list集合，collection="idList"，这里不再是list,而是包装类中对应的变量名，因为你传递的参数是一个包装类，mybatis是通过get方法获取包装类中的list集合 -->
<select id="selectUserVoByList" parameterType="UserVo" resultType="User">
select * from t_user where uid in
<foreach collection="idList" item="item" open="(" separator="," close=")">
#{item}
</foreach>
</select>
</mapper>1.如果你传参的时候直接传一个数组，那么使用foreach遍历时collection=“array”,这里是固定写法，即这里的array与你的实参名无关
2.如果你传参的时候直接传一list集合，那么使用foreach遍历时collection=“list”,这里是固定写法，即这里的list与你的实参名无关
3.如果你传参的时候直接传一个含有数组成员变量的类，那么使用foreach遍历时collection=“你的变量名”,这里不再是固定写法，即这里的命名取决于成员变量的变量名，例如：成员变量名是test,那么就是collection=“test”
4.如果你传参的时候直接传一个含有list集合成员变量的类，跟3的情况一样
动态代理 xml方式
取消dao层的实现类
注意
mapper包的java文件和映射xml文件名相同 xml文件的namespace要映射到java文件 mybatis配置xml要设置映射文件到映射xml
sercice层
private SqlSession sqlSession = null;
private HouseingTypeMapper mapper = null;
public HouseingTypeSerciceImpl() throws IOException {
sqlSession = MybatisUtils.getSqlSession();
mapper = sqlSession.getMapper(HouseingTypeMapper.class);
}
/**
* 模糊查询
*
* @param value
* @return
*/
@Override
public List<HouseingType> fuzzyselectHouseingType(String value) {
return mapper.fuzzyselectHouseingType(value);
}
/**
* 插入数据
*
* @param houseingType
*/
@Override
public void insertHouseingType(HouseingType houseingType) {
mapper.insertHouseingType(houseingType);
sqlSession.commit();
}
lib问题
解决
映射xml和java文件放在一起
<!-- pom.xml -->
<!-- xml映射文件放到java文件一起-->
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>查看配置映射文件
<!-- mybatisConfig 配置文件-->
<mappers>
<!-- <mapper resource="data/HouseingTypeMapper.xml"></mapper> -->
<!-- 配置java文件和xml文件放在一起，识别-->
<mapper class="com.mapper.HouseingTypeMapper"></mapper>
</mappers>动态代理 注解方式
删除xml映射文件 对应的sql语句配置 设置对应接口的@注解
/**
* 无条件查询-查询所有
* @return
*/
@Select("select * from housingtype")
List<HouseingType> selectHouseingType();
/**
* 单条件查询-精确查询
* @return
*/
@Select("select * from housingtype where typeId = #{typeId}")
HouseingType conditionHouseingType(Integer typeId);<where>
<select id="checkRecordVoAsCondition" parameterType="CheckRecordVo" resultType="CheckhouseRecord">
select * from checkhouserecord
<where>
<if test="checkhouseRecord.account != null">
account=#{checkhouseRecord.account}
</if>
<if test="minTime != null || maxTime != null">
and checkDate between #{minTime} and #{maxTime}
</if>
</where>
</select>EL表达式实体类问题
ResultMap
<resultMap id="selectAllResultMap" type="HouseingType">
<id column="typeId" property="typeId" /> <!-- 映射主键 colimn:映射数据库字段 property:pojo实体类-->
<result column="typename" property="typename"/>
</resultMap>
<!-- 无条件查询-->
<select id="selectHouseingType" resultMap="selectAllResultMap">
select * from housingtype
</select>一对一
<resultMap id="landlordhousingResultMap" type="Housing">
<id column="hid" property="hId"/>
<result column="title" property="title"/>
<result column="rent" property="rent"/>
<result column="houseType" property="houseType"/>
<result column="area" property="area"/>
<result column="towardId" property="towardId"/>
<result column="imgList" property="imgList"/>
<result column="facilities" property="facilities"/>
<result column="state" property="state"/>
<result column="aid" property="aid"/>
<result column="address" property="address"/>
<result column="describe" property="describe"/>
<association property="landlord" javaType="com.pojo.Landlord">
<id column="lId" property="lId"></id>
<result column="lName" property="lName"/>
<result column="phone" property="phone"/>
<result column="address" property="address"/>
<result column="idCard" property="idCard"/>
<result column="account" property="account"/>
</association>
</resultMap>
<select id="selectLandlordHousing" resultMap="landlordhousingResultMap">
select *
from landlord l
inner join housing h on l.lId=h.lid
</select>一对多
<resultMap id="landlordResultMap" type="Landlord">
<id property="lId" column="lId" />
<result property="lName" column="lName"/>
<result property="phone" column="phone"/>
<result property="address" column="address"/>
<result property="account" column="account"/>
<collection property="housings" ofType="Housing">
<id column="hid" property="hId"/>
<result column="title" property="title"/>
<result column="rent" property="rent"/>
<result column="houseType" property="houseType"/>
<result column="area" property="area"/>
<result column="towardId" property="towardId"/>
<result column="imgList" property="imgList"/>
<result column="facilities" property="facilities"/>
<result column="state" property="state"/>
<result column="aid" property="aid"/>
<result column="address" property="address"/>
<result column="describe" property="describe"/>
</collection>
</resultMap>
<select id="selectHouseLand" resultMap="landlordResultMap">
select *
from landlord l
left join housing h on l.lid=h.lId
</select>Mybatis-plus
命名问题：https://blog.csdn.net/Zack_tzh/article/details/107487209
pojo实体类名称为驼峰命名包含大写，mybatis-plus默认会转换为蛇形命名
pom.xml
# 要删除mybatis依赖
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus</artifactId>
<version>3.4.2</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>2.0.4</version>
</dependency>mybatis.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
</configuration>applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<context:property-placeholder location="classpath:db.properties" />
<!--组件扫描：用于注解-->
<context:component-scan base-package="com.mybatisplus"/>
<!--数据库连接池（德鲁伊连接池）-->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
<property name="driverClassName" value="${jdbc.driver}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.user}" />
<property name="password" value="${jdbc.password}" />
</bean>
<bean id="sqlSessionFactory" class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!-- 加载mybatis配置文件-->
<property name="configLocation" value="classpath:mybatis.xml"/>
<!-- 别名处理-->
<property name="typeAliasesPackage" value="com.mybatisplus.pojo"/>
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.mybatisplus.mapper"/>
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
</bean>
</beans>CRUD
package com.Demo;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.mybatisplus.mapper.DepartmentMapper;
import com.mybatisplus.mapper.EmployeeMapper;
import com.mybatisplus.pojo.Department;
import com.mybatisplus.pojo.Employee;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import javax.annotation.Resource;
import java.util.List;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:applicationContext.xml"})
public class Test1 {
@Resource
private DepartmentMapper departmentMapper;
@Resource
private EmployeeMapper employeeMapper;
@Test
//查询
public void test1() {
QueryWrapper<Employee> queryWrap = new QueryWrapper<>();
queryWrap.like("sex", "男");
List<Employee> employees = employeeMapper.selectList(queryWrap);
for (Employee employee : employees) {
System.out.println(employee);
}
}
@Test
//添加
public void test2() {
Department department = new Department();
// 遇到主键auto_incremnet时，不用设置
department.setPid(303);
department.setPname("绝密");
int insert = departmentMapper.insert(department);
if (insert > 0) {
System.out.println("插入成功！");
}
}
@Test
//添加
public void test2_1() {
Employee employee = new Employee(null, "FIB", "男", 303, 15000.0, "云南省", "海军陆战队", "***");
int insert = employeeMapper.insert(employee);
if (insert > 0) {
System.out.println("插入成功！");
}
}
@Test
// 删除
public void test3() {
QueryWrapper<Department> queryWrap = new QueryWrapper<>();
queryWrap.like("pname", "密");
int delete = departmentMapper.delete(queryWrap);
if (delete > 0) {
System.out.println("删除成功！");
}
}
@Test
public void test4() {
QueryWrapper<Department> wrapper = new QueryWrapper<>();
wrapper.eq("pid", 303);
Department department = departmentMapper.selectOne(wrapper);
department.setPid(404);
int update = departmentMapper.update(department,wrapper);
if (update > 0) {
System.out.println("修改成功！");
}
}
}主键自增策略
@TableId(value = "id",type = IdType.AUTO)
