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
Mapper CRUD 接口
使用: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
insert// 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
select// 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) WrapperqueryWrapper); // 查询(根据ID 批量查询) List selectBatchIds(@Param(Constants.COLLECTION) Collection extends Serializable> idList); // 根据 entity 条件,查询全部记录 List selectList(@Param(Constants.WRAPPER) Wrapper queryWrapper); // 查询(根据 columnMap 条件) List selectByMap(@Param(Constants.COLUMN_MAP) Map columnMap); // 根据 Wrapper 条件,查询全部记录 List
参数说明:
测试:
SelectByIdAndBatchIds()@Test
void mapperSelectByIdAndBatchIds() {
String id1 = "1556577794717298690";
String id2 = "1556592930551185410";
String id3 = "1556593922332053506";
List 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 singers = singerMapper.selectBatchIds(ids);
System.out.println("===================根据多个id查询:");
singers.forEach(System.out::println);
}
控制台输出:
selectOne@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:
selcetList@Test
void mapperSelectList() {
List singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
控制台输出:
selectByMap@Test
void mapperSelectByMap() {
Map map=new HashMap<>();
map.put("age",18);
List singers = singerMapper.selectByMap(map);
singers.forEach(System.out::println);
}
控制台输出:
selectMaps@Test
void mapperSelectMaps() {
List
控制台输出:
selectObjs注意:此方法只返回第一个字段的值
@Test
void mapperSelectObjs() {
List
控制台输出:
selectPage@Test
void mapperSelectPage() {
IPage singerIPage = singerMapper.selectPage(new Page<>(1,10), null);
singerIPage.getRecords().forEach(System.out::println);
}
控制台输出:
selectMapsPage@Test
void mapperSelectMapsPage() {
Page
控制台输出:
selectCount@Test
void mapperSelectCount() {
Long count = singerMapper.selectCount(null);
System.out.println("count = " + count);
}
update
// 根据 whereWrapper 条件,更新记录 int update(@Param(Constants.ENTITY) T updateEntity, @Param(Constants.WRAPPER) WrapperwhereWrapper); // 根据 ID 修改 int updateById(@Param(Constants.ENTITY) T entity);
@Test
void mapperUpdate() {
QueryWrapper 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 singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperUpdateById() {
QueryWrapper 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 singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
delete
@Test
void mapperDelete(){
QueryWrapper wrapper = new QueryWrapper<>();
wrapper.eq("age",22);
singerMapper.delete(wrapper);
System.out.println("=============================delete======================================");
List singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDeleteBatchsIds(){
ArrayList ids = new ArrayList<>();
ids.add("1556830638657703938");
singerMapper.deleteBatchIds(ids);
System.out.println("=============================delete======================================");
List singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDeleteByMap(){
Map map=new HashMap<>();
map.put("age",22);
singerMapper.deleteByMap(map);
System.out.println("=============================delete======================================");
List singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
Service CRUD接口
使用 Save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(CollectionentityList); // 插入(批量) boolean saveBatch(Collection entityList, int batchSize);
注意:service的插入返回的是布尔类型
批次插入
SaveOrUpdate// 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, WrapperupdateWrapper); // 批量修改插入 boolean saveOrUpdateBatch(Collection entityList); // 批量修改插入 boolean saveOrUpdateBatch(Collection 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
如果有id会先查询数据有就更新没有则执行插入
如果还传了wrapper要注意null值会导致对所有数据更新
Remove// 根据 entity 条件,删除记录 boolean remove(WrapperUpdatequeryWrapper); // 根据 ID 删除 boolean removeById(Serializable id); // 根据 columnMap 条件,删除记录 boolean removeByMap(Map 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(WrapperupdateWrapper); // 根据 whereWrapper 条件,更新记录 boolean update(T updateEntity, Wrapper whereWrapper); // 根据 ID 选择修改 boolean updateById(T entity); // 根据ID 批量更新 boolean updateBatchById(Collection entityList); // 根据ID 批量更新 boolean updateBatchById(Collection entityList, int batchSize);
这两和mapper没多大区别,略!
Get// 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 queryWrapper);
// 根据 Wrapper,查询一条记录
T getOne(Wrapper queryWrapper, boolean throwEx);
// 根据 Wrapper,查询一条记录
Map getMap(Wrapper queryWrapper);
// 根据 Wrapper,查询一条记录
V getObj(Wrapper queryWrapper, Function super Object, V> mapper);
@Test
void serviceGet(){
QueryWrapper 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 wrapper=new QueryWrapper();
wrapper.eq("age",18);
Map 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。
List// 查询所有 Listlist(); // 查询列表 List list(Wrapper queryWrapper); // 查询(根据ID 批量查询) Collection listByIds(Collection extends Serializable> idList); // 查询(根据 columnMap 条件) Collection listByMap(Map columnMap); // 查询所有列表 List
@Test
void list(){
List list = singerService.list();
QueryWrapper wrapper=new QueryWrapper();
wrapper.eq("age",18);
List list2 = singerService.list(wrapper);
List> maps = singerService.listMaps();
maps.forEach(System.out::println);
List> maps2 = singerService.listMaps(wrapper);
maps2.forEach(System.out::println);
}
Page
// 无条件分页查询 IPagepage(IPage page); // 条件分页查询 IPage page(IPage page, Wrapper queryWrapper); // 无条件分页查询 IPage > pageMaps(IPage page); // 条件分页查询 IPage > pageMaps(IPage page, Wrapper queryWrapper);
@Test
void page(){
Page page = singerService.page(new Page<>(1, 5));
page.getRecords().forEach(System.out::println);
Page> mapPage = singerService.pageMaps(new Page<>(1, 5));
mapPage.getRecords().forEach(System.out::println);
}
Count
// 查询总记录数 int count(); // 根据 Wrapper 条件,查询总记录数 int count(WrapperChain queryqueryWrapper);
// 链式查询 普通 QueryChainWrapperquery(); // 链式查询 lambda 式。注意:不支持 Kotlin LambdaQueryChainWrapper 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 list = singerService.lambdaQuery().eq(Singer::getName, "周杰伦").list();
list.forEach(System.out::println);
}
update
// 链式更改 普通 UpdateChainWrapperupdate(); // 链式更改 lambda 式。注意:不支持 Kotlin LambdaUpdateChainWrapper 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 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 singers = singerMapper.selectBatchIds(ids);
System.out.println("===================根据多个id查询:");
singers.forEach(System.out::println);
}
@Test
void mapperSelectOne() {
QueryWrapper wrapper = new QueryWrapper<>();
wrapper.eq("age",18);
Singer singer = singerMapper.selectOne(wrapper);
System.out.println("singer = " + singer.toString());
}
@Test
void mapperSelectList() {
List singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperSelectByMap() {
Map map=new HashMap<>();
map.put("age",18);
List singers = singerMapper.selectByMap(map);
singers.forEach(System.out::println);
}
@Test
void mapperSelectMaps() {
List> maps = singerMapper.selectMaps(null);
maps.forEach(System.out::println);
}
@Test
void mapperSelectObjs() {
List objects = singerMapper.selectObjs(null);
objects.forEach(System.out::println);
}
@Test
void mapperSelectPage() {
IPage singerIPage = singerMapper.selectPage(new Page<>(1,10), null);
singerIPage.getRecords().forEach(System.out::println);
}
@Test
void mapperSelectMapsPage() {
Page> 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 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 singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperUpdateById() {
QueryWrapper 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 singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDelete(){
QueryWrapper wrapper = new QueryWrapper<>();
wrapper.eq("age",22);
singerMapper.delete(wrapper);
System.out.println("=============================delete======================================");
List singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDeleteBatchsIds(){
ArrayList ids = new ArrayList<>();
ids.add("1556830638657703938");
singerMapper.deleteBatchIds(ids);
System.out.println("=============================delete======================================");
List singers = singerMapper.selectList(null);
singers.forEach(System.out::println);
}
@Test
void mapperDeleteByMap(){
Map map=new HashMap<>();
map.put("age",22);
singerMapper.deleteByMap(map);
System.out.println("=============================delete======================================");
List 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 singers=new ArrayList<>();
singers.add(singer1);
singers.add(singer2);
boolean save = singerService.saveBatch(singers,1);
System.out.println("save = " + save);
List 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 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 wrapper=new QueryWrapper();
wrapper.eq("age",18);
Map map = singerService.getMap(wrapper);
System.out.println("map = " + map);
}
@Test
void list(){
List list = singerService.list();
QueryWrapper wrapper=new QueryWrapper();
wrapper.eq("age",18);
List list2 = singerService.list(wrapper);
List> maps = singerService.listMaps();
maps.forEach(System.out::println);
List> maps2 = singerService.listMaps(wrapper);
maps2.forEach(System.out::println);
}
@Test
void page(){
Page page = singerService.page(new Page<>(1, 5));
page.getRecords().forEach(System.out::println);
Page> 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 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);
}
}



