官网参考链接:https://baomidou.com/pages/49cc81/#service-crud-%E6%8E%A5%E5%8F%A3
工程项目续用上一篇:MyBatisPlus入门学习:利用MP代码生成器快速开发
结构图:
在application.yml
文件加上日志输出可以打印sql语句
mybatis-plus:
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
说明:
- 通用 CRUD 封装BaseMapper接口,为
Mybatis-Plus
启动时自动解析实体表关系映射转换为Mybatis
内部对象注入容器- 泛型
T
为任意实体对象- 参数
Serializable
为任意类型主键Mybatis-Plus
不推荐使用复合主键约定每一张表都有自己的唯一id
主键- 对象
Wrapper
为 条件构造器
在MpDemoApplicationTests
添加方法
// 插入一条记录
int insert(T entity);
@Test
void mapperInsert(){
Singer singer=new Singer();
singer.setName("陶喆");
singer.setAge(22);
singer.setOther("空无一人 这片沙滩~");
int i = singerMapper.insert(singer);
System.out.println("i = " + i);
}
注意返回值是int类型,返回的也不是id,返回1代表插入成功
// 根据 ID 查询
T selectById(Serializable id);
// 根据 entity 条件,查询一条记录
T selectOne(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
// 查询(根据ID 批量查询)
List<T> selectBatchIds(@Param(Constants.COLLECTION) Collection<? extends Serializable> idList);
// 根据 entity 条件,查询全部记录
List<T> selectList(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
// 查询(根据 columnMap 条件)
List<T> selectByMap(@Param(Constants.COLUMN_MAP) Map<String, Object> columnMap);
// 根据 Wrapper 条件,查询全部记录
List<Map<String, Object>> selectMaps(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
// 根据 Wrapper 条件,查询全部记录。注意: 只返回第一个字段的值
List<Object> selectObjs(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
// 根据 entity 条件,查询全部记录(并翻页)
IPage<T> selectPage(IPage<T> page, @Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
// 根据 Wrapper 条件,查询全部记录(并翻页)
IPage<Map<String, Object>> selectMapsPage(IPage<T> page, @Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
// 根据 Wrapper 条件,查询总记录数
Integer selectCount(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
参数说明:
测试:
@Test
void mapperSelectByIdAndBatchIds() {
String id1 = "1556577794717298690";
String id2 = "1556592930551185410";
String id3 = "1556593922332053506";
List<String> ids= new ArrayList<>();
ids.add(id1);
ids.add(id2);
ids.add(id3);
Singer singer = singerMapper.selectById(id1);
System.out.println("===================根据单个id查询:\n"+singer.toString());
List<Singer> singers = singerMapper.selectBatchIds(ids);
System.out.println("===================根据多个id查询:");
singers.forEach(System.out::println);
}
控制台输出:
@Test
void mapperSelectOne() {
QueryWrapper wrapper = new QueryWrapper<>();
wrapper.eq("age",18);
Singer singer = singerMapper.selectOne(wrapper);
System.out.println("singer = " + singer.toString());
}
控制台输出:
@Test
void mapperSelectList() {
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
控制台输出:
@Test
void mapperSelectByMap() {
Map map=new HashMap<>();
map.put("age",18);
List<Singer> singers = singerMapper.selectByMap(map);
singers.forEach(System.out::println);
}
控制台输出:
@Test
void mapperSelectMaps() {
List<Map<String, Object>> maps = singerMapper.selectMaps(null);
maps.forEach(System.out::println);
}
控制台输出:
注意:此方法只返回第一个字段的值
@Test
void mapperSelectObjs() {
List<Object> objects = singerMapper.selectObjs(null);
objects.forEach(System.out::println);
}
控制台输出:
@Test
void mapperSelectPage() {
IPage<Singer> singerIPage = singerMapper.selectPage(new Page<>(1,10), null);
singerIPage.getRecords().forEach(System.out::println);
}
控制台输出:
@Test
void mapperSelectMapsPage() {
Page<Map<String, Object>> mapPage = singerMapper.selectMapsPage(new Page<>(1, 10), null);
mapPage.getRecords().forEach(System.out::println);
}
控制台输出:
@Test
void mapperSelectCount() {
Long count = singerMapper.selectCount(null);
System.out.println("count = " + count);
}
// 根据 whereWrapper 条件,更新记录
int update(@Param(Constants.ENTITY) T updateEntity, @Param(Constants.WRAPPER) Wrapper whereWrapper);
// 根据 ID 修改
int updateById(@Param(Constants.ENTITY) T entity);
@Test
void mapperUpdate() {
QueryWrapper<Singer> wrapper = new QueryWrapper<>();
wrapper.eq("age",17);
Singer singer = singerMapper.selectOne(wrapper);
System.out.println("singer.toString() = " + singer.toString());
singer.setOther("改一下");
singerMapper.update(singer,wrapper);
System.out.println("=============================update======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperUpdateById() {
QueryWrapper<Singer> wrapper = new QueryWrapper<>();
wrapper.eq("age",17);
Singer singer = singerMapper.selectOne(wrapper);
System.out.println("singer.toString() = " + singer.toString());
singer.setOther("改回来");
singerMapper.updateById(singer);
System.out.println("=============================update======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDelete(){
QueryWrapper<Singer> wrapper = new QueryWrapper<>();
wrapper.eq("age",22);
singerMapper.delete(wrapper);
System.out.println("=============================delete======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDeleteBatchsIds(){
ArrayList<String> ids = new ArrayList<>();
ids.add("1556830638657703938");
singerMapper.deleteBatchIds(ids);
System.out.println("=============================delete======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDeleteByMap(){
Map<String,Object> map=new HashMap<>();
map.put("age",22);
singerMapper.deleteByMap(map);
System.out.println("=============================delete======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
说明:
- 通用 Service CRUD 封装IService 接口,进一步封装 CRUD 采用
get 查询单行
remove 删除
list 查询集合
page 分页
前缀命名方式区分Mapper
层避免混淆,- 泛型
T
为任意实体对象- 建议如果存在自定义通用 Service 方法的可能,请创建自己的
IBaseService
继承Mybatis-Plus
提供的基类- 对象
Wrapper
为 条件构造器
// 插入一条记录(选择字段,策略插入)
boolean save(T entity);
// 插入(批量)
boolean saveBatch(Collection<T> entityList);
// 插入(批量)
boolean saveBatch(Collection<T> entityList, int batchSize);
注意:service的插入返回的是布尔类型
批次插入
// TableId 注解存在更新记录,否插入一条记录
boolean saveOrUpdate(T entity);
// 根据updateWrapper尝试更新,否继续执行saveOrUpdate(T)方法
boolean saveOrUpdate(T entity, Wrapper<T> updateWrapper);
// 批量修改插入
boolean saveOrUpdateBatch(Collection<T> entityList);
// 批量修改插入
boolean saveOrUpdateBatch(Collection<T> entityList, int batchSize);
//TableId 注解存在更新记录,否则插入一条记录
singerService.saveOrUpdate(singer);
singer.setAge(16);
//这里wrapper为null会更新所有数据,慎用。。。我
singerService.saveOrUpdate(singer,null);
saveOrUpdate()这里要注意:
entity如果没有id会直插入
如果还传了wrapper要注意null
值会导致对所有数据更新
// 根据 entity 条件,删除记录
boolean remove(Wrapper<T> queryWrapper);
// 根据 ID 删除
boolean removeById(Serializable id);
// 根据 columnMap 条件,删除记录
boolean removeByMap(Map<String, Object> columnMap);
// 删除(根据ID 批量删除)
boolean removeByIds(Collection<? extends Serializable> idList);
// 根据 UpdateWrapper 条件,更新记录 需要设置sqlset
boolean update(Wrapper<T> updateWrapper);
// 根据 whereWrapper 条件,更新记录
boolean update(T updateEntity, Wrapper<T> whereWrapper);
// 根据 ID 选择修改
boolean updateById(T entity);
// 根据ID 批量更新
boolean updateBatchById(Collection<T> entityList);
// 根据ID 批量更新
boolean updateBatchById(Collection<T> entityList, int batchSize);
这两和mapper没多大区别,略!
// 根据 ID 查询
T getById(Serializable id);
// 根据 Wrapper,查询一条记录。结果集,如果是多个会抛出异常,随机取一条加上限制条件 wrapper.last("LIMIT 1")
T getOne(Wrapper<T> queryWrapper);
// 根据 Wrapper,查询一条记录
T getOne(Wrapper<T> queryWrapper, boolean throwEx);
// 根据 Wrapper,查询一条记录
Map<String, Object> getMap(Wrapper<T> queryWrapper);
// 根据 Wrapper,查询一条记录
<V> V getObj(Wrapper<T> queryWrapper, Function<? super Object, V> mapper);
@Test
void serviceGet(){
QueryWrapper<Singer> wrapper=new QueryWrapper();
Singer byId = singerService.getById("1556883204896604161");
System.out.println("byId = " + byId);
wrapper.eq("age",18);
wrapper.last("LIMIT 1");
singerService.getOne(wrapper,true);
Singer one = singerService.getOne(wrapper);
System.out.println("one = " + one);
}
getOne:结果集有多条会报异常
singerService.getOne(wrapper, false);
false则不报异常选择一条数据输出
或者加上wrapper.last(“LIMIT 1”);
Map
map多条返回一条数据不报错
@Test
void serviceGetMap(){
QueryWrapper<Singer> wrapper=new QueryWrapper();
wrapper.eq("age",18);
Map<String, Object> map = singerService.getMap(wrapper);
System.out.println("map = " + map);
}
// 根据 Wrapper,查询一条记录
这个没弄懂传的什么参数,后面再填坑吧。
// 查询所有
List<T> list();
// 查询列表
List<T> list(Wrapper<T> queryWrapper);
// 查询(根据ID 批量查询)
Collection<T> listByIds(Collection<? extends Serializable> idList);
// 查询(根据 columnMap 条件)
Collection<T> listByMap(Map<String, Object> columnMap);
// 查询所有列表
List<Map<String, Object>> listMaps();
// 查询列表
List<Map<String, Object>> listMaps(Wrapper<T> queryWrapper);
// 查询全部记录
List<Object> listObjs();
// 查询全部记录
<V> List<V> listObjs(Function<? super Object, V> mapper);
// 根据 Wrapper 条件,查询全部记录
List<Object> listObjs(Wrapper<T> queryWrapper);
// 根据 Wrapper 条件,查询全部记录
<V> List<V> listObjs(Wrapper<T> queryWrapper, Function<? super Object, V> mapper);
@Test
void list(){
List<Singer> list = singerService.list();
QueryWrapper<Singer> wrapper=new QueryWrapper();
wrapper.eq("age",18);
List<Singer> list2 = singerService.list(wrapper);
List<Map<String, Object>> maps = singerService.listMaps();
maps.forEach(System.out::println);
List<Map<String, Object>> maps2 = singerService.listMaps(wrapper);
maps2.forEach(System.out::println);
}
// 无条件分页查询
IPage<T> page(IPage<T> page);
// 条件分页查询
IPage<T> page(IPage<T> page, Wrapper<T> queryWrapper);
// 无条件分页查询
IPage<Map<String, Object>> pageMaps(IPage<T> page);
// 条件分页查询
IPage<Map<String, Object>> pageMaps(IPage<T> page, Wrapper<T> queryWrapper);
@Test
void page(){
Page<Singer> page = singerService.page(new Page<>(1, 5));
page.getRecords().forEach(System.out::println);
Page<Map<String, Object>> mapPage = singerService.pageMaps(new Page<>(1, 5));
mapPage.getRecords().forEach(System.out::println);
}
// 查询总记录数
int count();
// 根据 Wrapper 条件,查询总记录数
int count(Wrapper<T> queryWrapper);
// 链式查询 普通
QueryChainWrapper<T> query();
// 链式查询 lambda 式。注意:不支持 Kotlin
LambdaQueryChainWrapper<T> lambdaQuery();
// 示例:
query().eq("column", value).one();
lambdaQuery().eq(Entity::getId, value).list();
@Test
void query(){
Long count = singerService.query().eq("age", 18).count();
List<Singer> list = singerService.lambdaQuery().eq(Singer::getName, "周杰伦").list();
list.forEach(System.out::println);
}
// 链式更改 普通
UpdateChainWrapper<T> update();
// 链式更改 lambda 式。注意:不支持 Kotlin
LambdaUpdateChainWrapper<T> lambdaUpdate();
// 示例:
update().eq("column", value).remove();
lambdaUpdate().eq(Entity::getId, value).update(entity);
@Test
void update(){
Singer singer = new Singer();
singer.setName("周杰伦2");
singer.setAge(18);
singer.setOther("爱你穿越时间,两行来自秋末的眼泪");
singerService.update().eq("age", 18).remove();
singerService.lambdaUpdate().eq(Singer::getName,"周杰伦2").update(singer);
}
完整代码
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.mp_demo.entity.Singer;
import com.example.mp_demo.mapper.SingerMapper;
import com.example.mp_demo.service.SingerService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@SpringBootTest
class MpDemoApplicationTests {
@Autowired
private SingerMapper singerMapper;
@Autowired
private SingerService singerService;
@Test
void mapperInsert() {
Singer singer = new Singer();
singer.setName("陶喆");
singer.setAge(22);
singer.setOther("空无一人 这片沙滩~");
int i = singerMapper.insert(singer);
System.out.println("i = " + i);
}
@Test
void mapperSelectById() {
String id1 = "1556577794717298690";
String id2 = "1556592930551185410";
String id3 = "1556593922332053506";
List<String> ids = new ArrayList<>();
ids.add(id1);
ids.add(id2);
ids.add(id3);
Singer singer = singerMapper.selectById(id1);
System.out.println("===================根据单个id查询:\n" + singer.toString());
List<Singer> singers = singerMapper.selectBatchIds(ids);
System.out.println("===================根据多个id查询:");
singers.forEach(System.out::println);
}
@Test
void mapperSelectOne() {
QueryWrapper<Singer> wrapper = new QueryWrapper<>();
wrapper.eq("age",18);
Singer singer = singerMapper.selectOne(wrapper);
System.out.println("singer = " + singer.toString());
}
@Test
void mapperSelectList() {
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperSelectByMap() {
Map map=new HashMap<>();
map.put("age",18);
List<Singer> singers = singerMapper.selectByMap(map);
singers.forEach(System.out::println);
}
@Test
void mapperSelectMaps() {
List<Map<String, Object>> maps = singerMapper.selectMaps(null);
maps.forEach(System.out::println);
}
@Test
void mapperSelectObjs() {
List<Object> objects = singerMapper.selectObjs(null);
objects.forEach(System.out::println);
}
@Test
void mapperSelectPage() {
IPage<Singer> singerIPage = singerMapper.selectPage(new Page<>(1,10), null);
singerIPage.getRecords().forEach(System.out::println);
}
@Test
void mapperSelectMapsPage() {
Page<Map<String, Object>> mapPage = singerMapper.selectMapsPage(new Page<>(1, 10), null);
mapPage.getRecords().forEach(System.out::println);
}
@Test
void mapperSelectCount() {
Long count = singerMapper.selectCount(null);
System.out.println("count = " + count);
}
@Test
void mapperUpdate() {
QueryWrapper<Singer> wrapper = new QueryWrapper<>();
wrapper.eq("age",17);
Singer singer = singerMapper.selectOne(wrapper);
System.out.println("singer.toString() = " + singer.toString());
singer.setOther("改一下");
singerMapper.update(singer,wrapper);
System.out.println("=============================update======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperUpdateById() {
QueryWrapper<Singer> wrapper = new QueryWrapper<>();
wrapper.eq("age",17);
Singer singer = singerMapper.selectOne(wrapper);
System.out.println("singer.toString() = " + singer.toString());
singer.setOther("改回来");
singerMapper.updateById(singer);
System.out.println("=============================update======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDelete(){
QueryWrapper<Singer> wrapper = new QueryWrapper<>();
wrapper.eq("age",22);
singerMapper.delete(wrapper);
System.out.println("=============================delete======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDeleteBatchsIds(){
ArrayList<String> ids = new ArrayList<>();
ids.add("1556830638657703938");
singerMapper.deleteBatchIds(ids);
System.out.println("=============================delete======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDeleteByMap(){
Map<String,Object> map=new HashMap<>();
map.put("age",22);
singerMapper.deleteByMap(map);
System.out.println("=============================delete======================================");
List<Singer> singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void serviceSave() {
Singer singer = new Singer();
singer.setName("周杰伦2");
singer.setAge(18);
singer.setOther("爱你穿越时间,两行来自秋末的眼泪");
boolean save = singerService.save(singer);
System.out.println("save = " + save);
}
@Test
void serviceSaveBatch() {
Singer singer1 = new Singer();
singer1.setName("周杰伦7");
singer1.setAge(18);
singer1.setOther("不懂你的黑色幽默");
Singer singer2 = new Singer();
singer2.setName("周杰伦8");
singer2.setAge(18);
singer2.setOther("周杰伦周杰伦周杰伦周杰伦周杰伦,你的完美主义太彻底");
List<Singer> singers=new ArrayList<>();
singers.add(singer1);
singers.add(singer2);
boolean save = singerService.saveBatch(singers,1);
System.out.println("save = " + save);
List<Singer> list = singerService.list();
list.forEach(System.out::println);
}
@Test
void serviceSaveOrUpdate(){
Singer singer = new Singer();
singer.setId("214124123");
singer.setName("周杰伦001");
singer.setAge(15);
singer.setOther("爱像一阵风");
singerService.saveOrUpdate(singer);
singer.setAge(16);
// singerService.saveOrUpdate(singer,null);
}
@Test
void serviceSaveOrUpdateBatch(){
Singer singer = new Singer();
singer.setName("周杰伦2");
singer.setAge(18);
singer.setOther("爱你穿越时间,两行来自秋末的眼泪");
Singer singer3 = new Singer();
singer3.setName("周杰伦7");
singer3.setAge(18);
singer3.setOther("不懂你的黑色幽默");
Singer singer2 = new Singer();
singer2.setName("周杰伦8");
singer2.setAge(18);
singer2.setOther("周杰伦周杰伦周杰伦周杰伦周杰伦,你的完美主义太彻底");
Singer singer4 = new Singer();
singer4.setName("周杰伦9");
singer4.setAge(16);
singer4.setOther("我的城堡说欢迎光临");
List list=new ArrayList();
list.add(singer);
list.add(singer2);
list.add(singer3);
list.add(singer4);
singerService.saveOrUpdateBatch(list);
}
@Test
void serviceGet(){
QueryWrapper<Singer> wrapper=new QueryWrapper();
Singer byId = singerService.getById("1556883204896604161");
System.out.println("byId = " + byId);
wrapper.eq("age",18);
wrapper.last("LIMIT 1");
singerService.getOne(wrapper,true);
Singer one = singerService.getOne(wrapper);
System.out.println("one = " + one);
}
@Test
void serviceGetMap(){
QueryWrapper<Singer> wrapper=new QueryWrapper();
wrapper.eq("age",18);
Map<String, Object> map = singerService.getMap(wrapper);
System.out.println("map = " + map);
}
@Test
void list(){
List<Singer> list = singerService.list();
QueryWrapper<Singer> wrapper=new QueryWrapper();
wrapper.eq("age",18);
List<Singer> list2 = singerService.list(wrapper);
List<Map<String, Object>> maps = singerService.listMaps();
maps.forEach(System.out::println);
List<Map<String, Object>> maps2 = singerService.listMaps(wrapper);
maps2.forEach(System.out::println);
}
@Test
void page(){
Page<Singer> page = singerService.page(new Page<>(1, 5));
page.getRecords().forEach(System.out::println);
Page<Map<String, Object>> mapPage = singerService.pageMaps(new Page<>(1, 5));
mapPage.getRecords().forEach(System.out::println);
}
@Test
void query(){
Long count = singerService.query().eq("age", 18).count();
List<Singer> list = singerService.lambdaQuery().eq(Singer::getName, "周杰伦").list();
list.forEach(System.out::println);
}
@Test
void update(){
Singer singer = new Singer();
singer.setName("周杰伦2");
singer.setAge(18);
singer.setOther("爱你穿越时间,两行来自秋末的眼泪");
singerService.update().eq("age", 18).remove();
singerService.lambdaUpdate().eq(Singer::getName,"周杰伦2").update(singer);
}
}