MyBatis-Plus提供的默认Mapper能力
作者:互联网
MyBatis-Plus
提供的BaseMapper
接口,内置了很多单表CRUD
功能,我们只需要定义一个接口去继承它,就能瞬间拥有这些能力。
官方文档 传送门
下面,详细整理BaseMapper
提供的能力。
增
1. 传入实体Entity对象,添加一条记录
int insert(T entity);
例子:
@Test
public void testInsert() {
UserEntity user = new UserEntity();
user.setId(6L);
user.setName("Michael");
user.setAge(28);
user.setEmail("test6@baomidou.com");
userMapper.insert(user);
}
控制台打印出来的日志:
==> Preparing: INSERT INTO tb_user ( id, name, age, email ) VALUES ( ?, ?, ?, ? )
==> Parameters: 6(Long), Michael(String), 28(Integer), test6@baomidou.com(String)
<== Updates: 1
删
1. 传入主键ID的值,根据主键ID删除一条记录
int deleteById(Serializable id);
例子:
@Test
public void testDeleteById() {
userMapper.deleteById(6L);
}
控制台打印出来的日志:
==> Preparing: DELETE FROM tb_user WHERE id=?
==> Parameters: 6(Long)
<== Updates: 1
2. 传入实体Entity对象,根据实体中的主键ID删除一条数据
int deleteById(T entity);
例子:
@Test
public void testDeleteById2() {
UserEntity user = new UserEntity();
user.setId(6L);
userMapper.deleteById(user);
}
设置主键ID就可以了。
控制台打印出来的日志:
==> Preparing: DELETE FROM tb_user WHERE id=?
==> Parameters: 6(Long)
<== Updates: 1
3. 根据 columnMap 条件,删除记录
int deleteByMap(@Param(Constants.COLUMN_MAP) Map<String, Object> columnMap);
columnMap
中传入where
条件字段和值。
支持AND
、等值匹配。
例子:
@Test
public void testDeleteByMap() {
Map<String, Object> columnMap = new HashMap<>();
columnMap.put("name", "Billie");
columnMap.put("age", 24);
userMapper.deleteByMap(columnMap);
}
控制台打印出来的日志:
==> Preparing: DELETE FROM tb_user WHERE name = ? AND age = ?
==> Parameters: Billie(String), 24(Integer)
<== Updates: 1
4. 根据wrapper条件删除记录
int delete(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
queryWrapper
封装Entity
,作为where
条件。
支持非等值匹配。
例子:
@Test
public void testDeleteByWrapper() {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.likeRight("name", "J");
userMapper.delete(wrapper);
}
控制台打印出来的日志:
==> Preparing: DELETE FROM tb_user WHERE (name LIKE ?)
==> Parameters: J%(String)
<== Updates: 2
5. 根据主键ID集合批量删除记录
int deleteBatchIds(@Param(Constants.COLLECTION) Collection<? extends Serializable> idList);
例子:
@Test
public void testDeleteBatchIds() {
List<Long> ids = Arrays.asList(3L, 4L);
userMapper.deleteBatchIds(ids);
}
控制台打印出来的日志:
==> Preparing: DELETE FROM tb_user WHERE id IN ( ? , ? )
==> Parameters: 3(Long), 4(Long)
<== Updates: 2
改
1. 根据主键ID修改记录
int updateById(@Param(Constants.ENTITY) T entity);
例子:
@Test
public void testUpdateById() {
UserEntity user = new UserEntity();
user.setId(5L);
user.setAge(30);
user.setEmail("test5update@baomidou.com");
userMapper.updateById(user);
}
控制台打印出来的日志:
==> Preparing: UPDATE tb_user SET age=?, email=? WHERE id=?
==> Parameters: 30(Integer), test5update@baomidou.com(String), 5(Long)
<== Updates: 1
2. 根据wrapper条件更新记录
int update(@Param(Constants.ENTITY) T entity, @Param(Constants.WRAPPER) Wrapper<T> updateWrapper);
例子:
@Test
public void testUpdateByWrapper() {
UserEntity user = new UserEntity();
user.setAge(35);
user.setEmail("wrapperUpdate@baomidou.com");
UpdateWrapper<UserEntity> wrapper = new UpdateWrapper<>();
wrapper.ge("age", "28");
userMapper.update(user, wrapper);
}
控制台打印出来的日志:
==> Preparing: UPDATE tb_user SET age=?, email=? WHERE (age >= ?)
==> Parameters: 35(Integer), wrapperUpdate@baomidou.com(String), 28(String)
<== Updates: 2
查
1. 根据 ID 查询
T selectById(Serializable id);
例子:
@Test
public void testSelectById() {
UserEntity user = userMapper.selectById(1L);
System.out.println(user);
}
控制台打印出来的日志:
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE id=?
==> Parameters: 1(Long)
<== Columns: id, name, age, email
<== Row: 1, Jone, 18, test1@baomidou.com
<== Total: 1
2. 根据 ID集合 批量查询
List<T> selectBatchIds(@Param(Constants.COLLECTION) Collection<? extends Serializable> idList);
例子:
@Test
public void testSelectBatchIds() {
List<Long> ids = Arrays.asList(1L, 3L);
List<UserEntity> users = userMapper.selectBatchIds(ids);
System.out.println(users);
}
控制台打印出来的日志:
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE id IN ( ? , ? )
==> Parameters: 1(Long), 3(Long)
<== Columns: id, name, age, email
<== Row: 1, Jone, 18, test1@baomidou.com
<== Row: 3, Tom, 35, wrapperUpdate@baomidou.com
<== Total: 2
3. 根据 columnMap 条件批量查询
List<T> selectByMap(@Param(Constants.COLUMN_MAP) Map<String, Object> columnMap);
例子:
@Test
public void testSelectByMap() {
Map<String, Object> columnMap = new HashMap<>();
columnMap.put("age", 35);
List<UserEntity> users = userMapper.selectByMap(columnMap);
System.out.println(users);
}
控制台打印出来的日志:
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE age = ?
==> Parameters: 35(Integer)
<== Columns: id, name, age, email
<== Row: 3, Tom, 35, wrapperUpdate@baomidou.com
<== Row: 5, Billie, 35, wrapperUpdate@baomidou.com
<== Total: 2
4. 根据 Wrapper 条件查询一条记录
default T selectOne(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper) {
List<T> ts = this.selectList(queryWrapper);
if (CollectionUtils.isNotEmpty(ts)) {
if (ts.size() != 1) {
throw ExceptionUtils.mpe("One record is expected, but the query result is multiple records");
}
return ts.get(0);
}
return null;
}
注:如果查出来有多条,会报错。
例子:
@Test
public void testSelectOne() {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq("name", "Tom");
UserEntity user = userMapper.selectOne(wrapper);
System.out.println(user);
}
控制台打印出来的日志:
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE (name = ?)
==> Parameters: Tom(String)
<== Columns: id, name, age, email
<== Row: 3, Tom, 35, wrapperUpdate@baomidou.com
<== Total: 1
5. 根据 Wrapper 条件,查询总记录数
Long selectCount(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
例子:
@Test
public void testSelectCount() {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq("age", 35);
long count = userMapper.selectCount(wrapper);
System.out.println(count);
}
控制台打印出来的日志:
==> Preparing: SELECT COUNT( * ) FROM tb_user WHERE (age = ?)
==> Parameters: 35(Integer)
<== Columns: COUNT( * )
<== Row: 2
<== Total: 1
6. 根据 Wrapper 条件,批量查询Entity集合
List<T> selectList(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
例子:
@Test
public void testSelectList() {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq("age", 35);
List<UserEntity> users = userMapper.selectList(wrapper);
System.out.println(users);
}
控制台打印出来的日志:
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE (age = ?)
==> Parameters: 35(Integer)
<== Columns: id, name, age, email
<== Row: 3, Tom, 35, wrapperUpdate@baomidou.com
<== Row: 5, Billie, 35, wrapperUpdate@baomidou.com
<== Total: 2
7. 根据 Wrapper 条件,批量查询Map集合
List<Map<String, Object>> selectMaps(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
例子:
@Test
public void testSelectMaps() {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq("age", 35);
List<Map<String, Object>> users = userMapper.selectMaps(wrapper);
System.out.println(users);
}
控制台打印出来的日志:
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE (age = ?)
==> Parameters: 35(Integer)
<== Columns: id, name, age, email
<== Row: 3, Tom, 35, wrapperUpdate@baomidou.com
<== Row: 5, Billie, 35, wrapperUpdate@baomidou.com
<== Total: 2
8. 根据 Wrapper 条件,批量查询Object集合
List<Object> selectObjs(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
例子:
@Test
public void testSelectObjs() {
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq("age", 35);
List<Object> users = userMapper.selectObjs(wrapper);
System.out.println(users);
}
控制台打印出来的日志:
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE (age = ?)
==> Parameters: 35(Integer)
<== Columns: id, name, age, email
<== Row: 3, Tom, 35, wrapperUpdate@baomidou.com
<== Row: 5, Billie, 35, wrapperUpdate@baomidou.com
<== Total: 2
9. 根据 Page 和 Wrapper 条件,分页查询Entity记录
<P extends IPage<T>> P selectPage(P page, @Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
例子:
@Test
public void testSelectPage() {
// 查询第1页,每页显示1条记录
Page<UserEntity> page = new Page<>(1, 1);
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq("age", 35);
Page<UserEntity> pageResult = userMapper.selectPage(page, wrapper);
System.out.println(JSON.toJSONString(pageResult));
}
控制台打印出来的日志:
==> Preparing: SELECT COUNT(*) FROM tb_user WHERE (age = ?)
==> Parameters: 35(Integer)
<== Columns: COUNT(*)
<== Row: 2
<== Total: 1
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE (age = ?) LIMIT ?
==> Parameters: 35(Integer), 1(Long)
<== Columns: id, name, age, email
<== Row: 3, Tom, 35, wrapperUpdate@baomidou.com
<== Total: 1
查询结果:
{
"current": 1,
"optimizeCountSql": true,
"orders": [],
"pages": 2,
"records": [
{
"age": 35,
"email": "wrapperUpdate@baomidou.com",
"id": 3,
"name": "Tom"
}
],
"searchCount": true,
"size": 1,
"total": 2
}
注意:必须配置数据库方言,分页查询才会生效。
数据库方言配置:
@Configuration
public class MyBatisPlusConfig {
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
// 配置自己使用的数据库,这里我选择MYSQL
interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
return interceptor;
}
}
10. 根据 Page 和 Wrapper 条件,分页查询Map记录
<P extends IPage<Map<String, Object>>> P selectMapsPage(P page, @Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
例子:
@Test
public void testSelectMapsPage() {
Page<Map<String, Object>> page = new Page<>(1, 1);
QueryWrapper<UserEntity> wrapper = new QueryWrapper<>();
wrapper.eq("age", 35);
Page<Map<String, Object>> pageResult = userMapper.selectMapsPage(page, wrapper);
System.out.println(JSON.toJSONString(pageResult));
}
注意:定义Page的时候,泛型传Map,不要传Entity。
控制台打印出来的日志:
==> Preparing: SELECT COUNT(*) FROM tb_user WHERE (age = ?)
==> Parameters: 35(Integer)
<== Columns: COUNT(*)
<== Row: 2
<== Total: 1
==> Preparing: SELECT id,name,age,email FROM tb_user WHERE (age = ?) LIMIT ?
==> Parameters: 35(Integer), 1(Long)
<== Columns: id, name, age, email
<== Row: 3, Tom, 35, wrapperUpdate@baomidou.com
<== Total: 1
查询结果:
{
"current": 1,
"optimizeCountSql": true,
"orders": [],
"pages": 2,
"records": [
{
"name": "Tom",
"id": 3,
"age": 35,
"email": "wrapperUpdate@baomidou.com"
}
],
"searchCount": true,
"size": 1,
"total": 2
}
标签:Mapper,age,wrapper,Plus,user,MyBatis,tb,public,Preparing 来源: https://blog.csdn.net/hbtj_1216/article/details/120250692