文章目录

• 1.前期准备
• 2.insert
• • 2.1 完成insert使用Map集合传参
  • 2.2 完成insert使用Pojo传参
• 3.delete
• 4.update
• 5.retrieve
• • 5.1 查一个
  • 5.2 查所有
• 6.关于SQL Mapper的namespace

1.前期准备

添加依赖

org.mybatismybatis3.5.10
mysqlmysql-connector-java5.1.37
ch.qos.logbacklogback-examples1.2.11
junitjunit4.13.2test

引入之前文件

2.insert

2.1 完成insert使用Map集合传参

CarMapper.xml

    insert into t_car(id, car_num, brand, guide_price, produce_time, car_type)values (null, #{car_num}, #{brand}, #{guide_price}, #{produce_time}, #{car_type})

测试

    @Testpublic void testInsertCar(){SqlSession sqlSession = SqlSessionUtil.openSession();Map map = new HashMap<>();map.put("car_num", 1111);map.put("brand", "比亚迪汉");map.put("guide_price", 10.0);map.put("produce_time", 2020-11-11);map.put("car_type", "电车");int count = sqlSession.insert("insertCar", map);System.out.println(count);sqlSession.commit();sqlSession.close();}

2.2 完成insert使用Pojo传参

Car.java

package com.sdnu.mybatis.pojo;public class Car {private Long id;private String carNum;private String brand;private Double guidePrice;private String produceTime;private String carType;public Car() {}public Car(Long id, String carNum, String brand, Double guidePrice, String produceTime, String carType) {this.id = id;this.carNum = carNum;this.brand = brand;this.guidePrice = guidePrice;this.produceTime = produceTime;this.carType = carType;}public Long getId() {return id;}public void setId(Long id) {this.id = id;}public String getCarNum() {return carNum;}public void setCarNum(String carNum) {this.carNum = carNum;}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public Double getGuidePrice() {return guidePrice;}public void setGuidePrice(Double guidePrice) {this.guidePrice = guidePrice;}public String getProduceTime() {return produceTime;}public void setProduceTime(String produceTime) {this.produceTime = produceTime;}public String getCarType() {return carType;}public void setCarType(String carType) {this.carType = carType;}@Overridepublic String toString() {return "Car{" +"id=" + id +", carNum='" + carNum + '\'' +", brand='" + brand + '\'' +", guidePrice=" + guidePrice +", produceTime='" + produceTime + '\'' +", carType='" + carType + '\'' +'}';}
}

CarMapper.xml

    insert into t_car(id, car_num, brand, guide_price, produce_time, car_type)values (null, #{carNum}, #{brand}, #{guidePrice}, #{produceTime}, #{carType})

测试类

    @Testpublic void testInsertCarByPojo(){SqlSession sqlSession = SqlSessionUtil.openSession();Car car = new Car(null, "1001", "比亚迪泰", 12.00, "2000-02-09", "电车");int count = sqlSession.insert("insertCar", car);System.out.println(count);sqlSession.commit();sqlSession.close();}

使用POJO对象传递值的话，#{}这个大括号中写的是get方法的方法名去掉get，然后将剩下的单词首字母小写，然后放进去。

 例如：getUsername() --> #{username}例如：getEmail() --> #{email}

3.delete

CarMapper.xml

    delete from t_car where id = #{id}

测试类

    @Testpublic void testDeleteCar(){SqlSession sqlSession = SqlSessionUtil.openSession();int count = sqlSession.delete("deleteById", 10);System.out.println(count);sqlSession.commit();sqlSession.close();}

4.update

CarMapper.xml

    update t_car setcar_num=#{carNum},brand=#{brand},guide_price=#{guidePrice},produce_time=#{produceTime},car_type=#{carType}whereid=#{id}

测试类

    @Testpublic void updateCarById(){SqlSession sqlSession = SqlSessionUtil.openSession();Car car = new Car(4L, "11111", "奔驰", 112.00, "2020-09-09", "燃油车");int count = sqlSession.update("updateById",car);System.out.println(count);sqlSession.commit();sqlSession.close();}

5.retrieve

5.1 查一个

CarMapper.xml

    selectid,car_num as carNum,brand,guide_price as guidePrice,produce_time as produceTime,car_type as carTypefromt_carwhereid = #{id}

测试类

    @Testpublic void selectById(){SqlSession sqlSession = SqlSessionUtil.openSession();Object car = sqlSession.selectOne("selectById", 3);System.out.println(car);sqlSession.commit();sqlSession.close();}

5.2 查所有

CarMapper.xml

    selectid,car_num as carNum,brand,guide_price as guidePrice,produce_time as produceTime,car_type as carTypefromt_car

测试类

    @Testpublic void  selectAll(){SqlSession sqlSession = SqlSessionUtil.openSession();List car = sqlSession.selectList("selectAll");for (Car car1 : car){System.out.println(car1);}sqlSession.close();}

6.关于SQL Mapper的namespace

在SQL Mapper配置⽂件中标签的namespace属性可以翻译为命名空间，这个命名空间主要是为了防⽌sqlId冲突的。