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.StdOutImplMapper 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"; Listids= 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() { QueryWrapperwrapper = 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() { Listsingers = 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); Listsingers = 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() { IPagesingerIPage = 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() { QueryWrapperdeletewrapper = 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(){ QueryWrapperService CRUD接口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); }
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(WrapperqueryWrapper); // 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(){ QueryWrapperwrapper=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(){ QueryWrapperwrapper=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(){ ListPagelist = 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); }
// 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(){ PageCountpage = 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); }
// 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(); Listupdatelist = singerService.lambdaQuery().eq(Singer::getName, "周杰伦").list(); list.forEach(System.out::println); }
// 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"; Listids = 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); } }