springboot整合mybatis plus 常见增删改查方法的应用

项目完整图，源码下载地址
download.csdn.net/download/qq_41712271/16690360


1 pom.xml配置

<dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><scope>runtime</scope>
</dependency><!--mybatis plus和springboot整合-->
<dependency><groupId>.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>3.4.1</version>
</dependency><dependency><groupId>.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional><scope>provided</scope>
</dependency>

2 application.properties配置

server.port=8081
#==============================数据库相关配置========================================
spring.datasource.driver-class-name =.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/cloud_guanggao?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.username =root
spring.datasource.password =123456#==============================mybatis plus 相关配置================================
#默认配置路径
mybatis-plus.mapper-locations=classpath*:/mapper/*Mapper.xml#配置mybatis plus打印sql日志
mybatis-plus.configuration.log-impl=.apache.ibatis.logging.stdout.StdOutImpl#mybatis plus下划线转驼峰配置，默认就是true
mybatis-plus.configuration.map-underscore-to-camel-case=true#配置文件配置 自定义sql的包扫描
mybatis-plus.type-aliases-package=.huawei.guanggao.pojo#配置全局默认主键类型,实体类就不用加 @TableId(value = "id", type = IdType.AUTO)
mybatis-plus.global-config.db-config.id-type=auto

3 pojo类GuangGao.java编写 和 对应的表

package .huawei.guanggao.pojo;
import .baomidou.mybatisplus.annotation.IdType;
import .baomidou.mybatisplus.annotation.TableField;
import .baomidou.mybatisplus.annotation.TableId;
import .baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.util.Date;//lombok 相关的注解，生成get,set,全参构造,无参构造
@Data
@AllArgsConstructor
@NoArgsConstructor//mybatis plus表名映射
@TableName("guanggao")
public class GuangGao {//mybatis plus 定义表的主键@TableId(value = "id",type = IdType.AUTO)private Integer id;private String title;//mybatis plus 定义表的非主键字段,因为和数据据的名称不一样，所以才设置，一般不用配置@TableField(value = "cover_img")private String coverImg;private Integer price;@TableField(value = "create_time")private Date createTime;private Double point;
}

4 mybatis plus配置类 MybatisPlusPageConfig.java（分页用）

package .huawei.guanggao.config;
import .baomidou.mybatisplus.annotation.DbType;
import .baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import .baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import .springframework.context.annotation.Bean;
import .springframework.context.annotation.Configuration;@Configuration
public class MybatisPlusPageConfig {/*  旧版本配置@Beanpublic PaginationInterceptor paginationInterceptor(){return new PaginationInterceptor();}*//*** 新的分页插件 ,拦截器的原理感觉*/@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor() {MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));return interceptor;}}

5 mapper层，GuangGaoMapper.java

package .huawei.guanggao.mapper;import .huawei.guanggao.pojo.GuangGao;
import .baomidou.mybatisplus.core.mapper.BaseMapper;
import java.util.List;/*** Mapper 继承该接口后，无需编写 mapper.xml 文件，即可获得CRUD功能*/
public interface GuangGaoMapper extends BaseMapper<GuangGao> {//也可以 自定义sql脚本List<GuangGao> getAllGuangGaoList();
}

6 GuangGaoMapper.xml文件 (可省略，只是演示如何使用自定义的sql)

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.//DTD Mapper 3.0//EN" "mybatis./dtd/mybatis-3-mapper.dtd">
<!--这个名称空间是Mapper接口的路径，记得修改-->
<mapper namespace=".huawei.guanggao.mapper.GuangGaoMapper"><select id="getAllGuangGaoList" resultType="GuangGao">select id,title,cover_img,price,create_time from guanggao</select></mapper>

7 启动类 GuanggaoApplication.java 编写

package .huawei.guanggao;
import .mybatis.spring.annotation.MapperScan;
import .springframework.boot.SpringApplication;
import .springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
@MapperScan(".huawei.guanggao.mapper")
public class GuanggaoApplication {public static void main(String[] args) {SpringApplication.run(GuanggaoApplication.class, args);}
}

8 增删改查方法测试用例 GuanggaoApplicationTests.java

package .huawei.guanggao;import .huawei.guanggao.mapper.GuangGaoMapper;
import .huawei.guanggao.pojo.GuangGao;
import .baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import .baomidou.mybatisplus.core.conditions.update.UpdateWrapper;
import .baomidou.mybatisplus.core.metadata.IPage;
import .baomidou.mybatisplus.extension.plugins.pagination.Page;
import .junit.jupiter.api.Test;
import .springframework.beans.factory.annotation.Autowired;
import .springframework.boot.test.context.SpringBootTest;
import java.util.*;
import java.util.function.Consumer;@SpringBootTest
class GuanggaoApplicationTests {@Autowiredprivate GuangGaoMapper guangGaoMapper;/*添加记录,并返回新增记录的id*/@Testvoid test_2() {GuangGao a = new GuangGao(null, "a", "a.jpg", 150, new Date(), 155.5);guangGaoMapper.insert(a);System.out.println(a.getId());}/*根据id删除，删除 id=66*/@Testvoid test_3() {guangGaoMapper.deleteById(66);}/*删除（根据ID 批量删除）DELETE FROM guanggao WHERE id IN (69,70)*/@Testvoid test_15() {guangGaoMapper.deleteBatchIds(Arrays.asList(69, 70));}/*根据 wrapper 条件，删除记录queryWrapper 实体对象封装操作类（可以为 null,里面的 entity 用于生成 where 语句DELETE FROM guanggao WHERE (id = 68ORid IN (67,68))*/@Testvoid test_14() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.eq("id", 68);wrapper.or();wrapper.in("id", 67, 68);guangGaoMapper.delete(wrapper);}/*通用删除操作 deleteByMap  map要写列名条件 不能是实体属性名删除 where id=67 and title=a*/@Testvoid test_4() {HashMap<String, Object> map = new HashMap<>();map.put("id", 67);map.put("title", "a");guangGaoMapper.deleteByMap(map);}/*修改操作，根据idUPDATE guanggao SET title=?, cover_img=? WHERE id=71*/@Testvoid test_16() {GuangGao guangGao = new GuangGao();guangGao.setTitle("光华大道");guangGao.setCoverImg("2.jpg");guangGao.setId(71);guangGaoMapper.updateById(guangGao);}/*queryWrapper更新操作修改 UPDATE guanggao SET title=?, cover_img=? WHERE (id = 65)*/@Testvoid test_5() {GuangGao guangGao = new GuangGao();guangGao.setTitle("森岛帆高");guangGao.setCoverImg("baidu./img/mv1.jpg");QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.eq("id", 65);guangGaoMapper.update(guangGao, wrapper);}/*updateWrapper更新操作UPDATE guanggao SET title=?,cover_img=? WHERE (id = ?)*/@Testvoid test_6() {UpdateWrapper<GuangGao> wrapper = new UpdateWrapper<>();wrapper.set("title", "大规模");wrapper.set("cover_img", "meilv_1.jpg");wrapper.eq("id", 64);guangGaoMapper.update(null, wrapper);}/*根据id查询 1个或多个FROM guanggao WHERE id=65FROM guanggao WHERE id IN ( 45, 46 )*/@Testvoid test_17() {GuangGao guangGao = guangGaoMapper.selectById(65);List<GuangGao> guangGaos = guangGaoMapper.selectBatchIds(Arrays.asList(45, 46));}/*查询操作 QueryWrapper*/@Testvoid test_1() {QueryWrapper<GuangGao> guangGaoQueryWrapper = new QueryWrapper<>();List<GuangGao> guangGaos =guangGaoMapper.selectList(guangGaoQueryWrapper);}/*QueryWrapper查询 基本操作,注意select的使用SELECT id,title FROM guanggao WHERE (id > 20)*/@Testvoid test_12() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.select("id", "title");wrapper.gt("id", 20);guangGaoMapper.selectList(wrapper);}/*查询操作 QueryWrapper ,并排序WHERE (id IN (60,61,62) AND price > 150)ORDER BY id DESC,title DESC*/@Testvoid test_10() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.in("id", Arrays.asList(60, 61, 62));wrapper.gt("price", 150);wrapper.orderByDesc("id", "title");List<GuangGao> guangGaos = guangGaoMapper.selectList(wrapper);}/*查询操作 QueryWrapper ，演示 apply,lickWHERE DATE_FORMAT(create_time,'%Y-%m-%d')>='2021-01-10' AND DATE_FORMAT(create_time,'%Y-%m-%d')<='2021-01-18' AND title LIKE '玩转%'*/@Testvoid test_7() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.apply("DATE_FORMAT(create_time,'%Y-%m-%d')>={0} and DATE_FORMAT(create_time,'%Y-%m-%d')<={1}", "2021-01-10", "2021-01-18");wrapper.likeRight("title", "玩转");List<GuangGao> guangGaos = guangGaoMapper.selectList(wrapper);}/*查询操作 QueryWrapper,演示多条件 is not null , between*** 注意：只要是用匿名内部类，生成的sql 是个组合，要用括号()起来的 ***WHERE (create_time IS NOT NULL AND title = ?OR(id BETWEEN ? AND ?))*/@Testvoid test_8() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.isNotNull("create_time");wrapper.eq("title", "森岛帆高");wrapper.or(new Consumer<QueryWrapper<GuangGao>>() {@Overridepublic void aept(QueryWrapper<GuangGao> queryWrapper) {queryWrapper.between("id", 60, 63);}});List<GuangGao> guangGaos = guangGaoMapper.selectList(wrapper);}/*查询操作 QueryWrapper*** 注意：只要是用匿名内部类，生成的sql 是个组合，要用括号()起来的 ***WHERE title LIKE ?AND(create_time IS NOT NULLORprice = ?)*/@Testvoid test_9() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.likeRight("title", "玩转");wrapper.and(new Consumer<QueryWrapper<GuangGao>>() {@Overridepublic void aept(QueryWrapper<GuangGao> queryWrapper) {queryWrapper.isNotNull("create_time");queryWrapper.or();queryWrapper.eq("price", 150);}});List<GuangGao> guangGaos = guangGaoMapper.selectList(wrapper);}/*wrapper 分页查询WHERE (id > 20) LIMIT (2-1)*5 ,5*/@Testvoid test_11() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.gt("id", 20);//第1页，每页2条Page<GuangGao> page = new Page<>(2, 5);IPage<GuangGao> bannerDOIPage = guangGaoMapper.selectPage(page, wrapper);System.out.println("总条数" + bannerDOIPage.getTotal());System.out.println("总页数" + bannerDOIPage.getPages());//获取当前数据System.out.println(bannerDOIPage.getRecords());}/*查询（根据 columnMap 条件）FROM guanggao WHERE id = 67 AND title = 'a'*/@Testvoid test_18() {HashMap<String, Object> map = new HashMap<>();map.put("id", 67);map.put("title", "a");List<GuangGao> guangGaos = guangGaoMapper.selectByMap(map);}/*根据 Wrapper 条件，结果只能有一条，否则会报错FROM guanggao WHERE (id = 63)*/@Testvoid test_19() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.eq("id", 63);GuangGao guangGao = guangGaoMapper.selectOne(wrapper);}/*根据 Wrapper 条件，查询总记录数SELECT COUNT( * ) FROM guanggao WHERE (id > 25)*/@Testvoid test_20() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.gt("id", 25);Integer integer = guangGaoMapper.selectCount(wrapper);System.out.println(integer);}/*根据 Wrapper 条件，查询全部记录SELECT price,count(price) as priceCount FROM guanggao GROUP BY price[{price=55, priceCount=3}, {price=66, priceCount=3}, {price=77, priceCount=3}]*/@Testvoid test_21() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.select("price", "count(price) as priceCount");wrapper.groupBy("price");List<Map<String, Object>> maps = guangGaoMapper.selectMaps(wrapper);System.out.println(maps);}/*根据 Wrapper 条件，查询全部记录<p>注意： 只返回第一个字段的值</p>SELECT title,cover_img,price FROM guanggao WHERE (id = 45 OR id IN (46, 47))[玩Docker实战, 新版javase, Nodejs教程]*/@Testvoid test_22() {QueryWrapper<GuangGao> wrapper = new QueryWrapper<>();wrapper.select("title", "cover_img", "price");wrapper.eq("id", 45);wrapper.or();wrapper.in("id", 46, 47);List<Object> objects = guangGaoMapper.selectObjs(wrapper);System.out.println(objects);}/*自定义sql脚本,在xml文件中编写，像mybatis那样*/@Testvoid test_13() {List<GuangGao> allGuangGaoList = guangGaoMapper.getAllGuangGaoList();System.out.println(allGuangGaoList);}
}