SpringBoot整合Mybatis-Plus
SpringBoot整合Mybatis-Plus
Mybatis-Plus 官网： https://baomidou.oschina.io/mybatis-plus-doc/#/spring-boot
一，pom引入:
<dependencies>
<dependency>
<groupId>com.baomidougroupId>
<artifactId>mybatis-plus-boot-starterartifactId>
<version>最新版本号version>
dependency>
dependencies>
<build>
<resources>
<resource>
<directory>src/main/javadirectory>
<filtering>falsefiltering>
<includes>
<include>**/mapper/*.xmlinclude>
includes>
resource>
resources>
build>
引入mybatis-plus后，mybatis，mybatis-spring不需要再引入
二，application.yml:
spring:
datasource:
url: jdbc:mysql://localhost:3306/mall?characterEncoding=utf-8&serverTimezone=GMT%2B8
username: root
password: 123456
# driver-class-name: com.mysql.cj.jdbc.Driver
server:
port: 8181
mybatis-plus:
# mapper-locations: classpath*:/mapper/**Mapper.xml
# #实体扫描，多个package用逗号或者分号分隔
# typeAliasesPackage: com.tdx.account_service.entity
global-config:
#主键类型 0:"数据库ID自增", 1:"用户输入ID",2:"全局唯一ID (数字类型唯一ID)", 3:"全局唯一ID UUID";
id-type: 0
#字段策略 0:"忽略判断",1:"非 NULL 判断"),2:"非空判断"
field-strategy: 2
#驼峰下划线转换
db-column-underline: true
#刷新mapper 调试神器
refresh-mapper: true
#数据库大写下划线转换
#capital-mode: true
#序列接口实现类配置
#key-generator: com.baomidou.springboot.xxx
#逻辑删除配置（下面3个配置）
logic-delete-value: 0
logic-not-delete-value: 1
#自定义SQL注入器
#sql-injector: com.baomidou.mybatisplus.mapper.LogicSqlInjector
#自定义填充策略接口实现
#meta-object-handler: com.baomidou.springboot.xxx
configuration:
map-underscore-to-camel-case: true
cache-enabled: false
# 是否将sql打印到控制面板(该配置会将sql语句和查询的结果都打印到控制台)
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
三，实体层
表名：
表名不一致需指定：通过实体类上加注解
@TableName(value = “admin”)
主键：
要标注主键和策略。否则会引起错误。也可以再配置文件内做全局处理
如果表主键名和实体主键名不一样，则需指定主键名 。
@TableId(value=“id”,type = IdType.AUTO) //主键自增策略
@TableName(value = "admin") //表名和实体不一致时需指明，一致可省略
@Data //：注解在类上,等同于@Getter、@Setter、@RequiredArgsConstructor、@ToString和@EqualsAndHashCode一起的效果 ---需要引入lombok和安装lombok插件
public class Admin extends Model<Admin> {
@TableId(type = IdType.AUTO) //主键自增策略
private Integer id;
private String username;
@TableLogic //逻辑删除注解
private Integer status;
@DateTimeFormat(pattern = "yyyy-MM-dd")
@JsonFormat(pattern = "yyyy-MM-dd")
private Date createdate;
时间格式化
@DateTimeFormat(pattern = "yyyy-MM-dd")
@JsonFormat(pattern = "yyyy-MM-dd")
private Date createdate;
四，持久层
1. Mybatis-Plus启动注入SQL原理
SqlSessionFactory => Configuration => MappedStatements
每一个mappedStatement 都表示 Mapper接口中的一个方法与Mapper映射文件中的一个SQL
MP在启动就会分析每个xxxMapper中的方法，并且讲对应的SQL语句处理好，保存到configuration对象内mappedStatements中。
2. 需继承BaseMapper，基本CRUD不用写
public interface AdminDao extends BaseMapper<Admin> {
}
BaseMapper 自带CRUD方法
public interface BaseMapper<T> {
int insert(T entity);
int deleteById(Serializable id);
int deleteByMap(@Param("cm") Map<String, Object> columnMap);
int delete(@Param("ew") Wrapper<T> wrapper);
int deleteBatchIds(@Param("coll") Collection<? extends Serializable> idList);
int updateById(@Param("et") T entity);
int update(@Param("et") T entity, @Param("ew") Wrapper<T> updateWrapper);
T selectById(Serializable id);
// 查询集合中多个主键值数据
List<T> selectBatchIds(@Param("coll") Collection<? extends Serializable> idList);
//根据Map条件查询
List<T> selectByMap(@Param("cm") Map<String, Object> columnMap);
//查询一个对象
T selectOne(@Param("ew") Wrapper<T> queryWrapper);
//记录查询数量
Integer selectCount(@Param("ew") Wrapper<T> queryWrapper);
//使用Wrapper对象作为查询条件
List<T> selectList(@Param("ew") Wrapper<T> queryWrapper);
//根据Map条件查询
List<Map<String, Object>> selectMaps(@Param("ew") Wrapper<T> queryWrapper);
List<Object> selectObjs(@Param("ew") Wrapper<T> queryWrapper);
//根据Wrapper条件并进行分页 page：分页查询条件 Wrapper:条件构造器
IPage<T> selectPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);
IPage<Map<String, Object>> selectMapsPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);
}
3. INSERT
insert：返回受影响的行数
@Test
public void insert(){
Admin admin =new Admin();
admin.setStatus(1);
admin.setUsername("mybatis-plus-insert");
admin.setCreatedate(new Date());
int i = adminDao.insert(admin);
// 主键是id，获取新添加记录的id，使用对象的getId()
int newId = admin.getId();
System.out.println(i+"新增加的ID是："+newId);
}
4. UPDATE
updateById：
根据主键修改，返回受影响的行数
注意：MP判断是否修改字段是判断属性的null，最好实体类Student的属性都是引用类型， 包括Integer status, 这样不给status赋值，就不会更新status字段。如果实体类定义 int status 。 修改结果是 status 是 0 ， 因为status 属性 int status ，这样定义int类型默认初值是 0 。
//根据主键修改对象
@Test
public void testUpdateAdmin(){
Admin admin =new Admin();
admin.setId(3);
admin.setUsername("新的名字");
admin.setStatus(1);
//根据主键修改对象， 对象null的属性，不进行修改
int rows = adminDao.updateById(admin);
}
5. DELETE:
//删除
deleteBatchIds(Collection); //参数是主键的集合，删除多条数据
delete(Wrapper); //根据Wrapper对象的条件，删除数据
deleteById(id);//根据单一主键，删除数据
deleteByMap(Map); //使用Map作为条件删除数据
deleteById:
根据主键删除，返回受影响的行数
//删除数据
@Test
public void testDeleteAdmin(){
// sql : DELETE FROM admin WHERE id=?
int rows = adminDao.deleteById(2);
System.out.println("deleteById结果："+rows);
}
deleteByMap:
删除指定条件的数据，返回受影响的行数
创建Map, 添加条件数据。Map的key是字段名，value是字段的值。调用deleteByMap(); 传入Map对象。 返回值成功删除的行数。
@Test
public void testDeleteAdminMap(){
Map<String,Object> condition = new HashMap<>();
condition.put("username","新的名字");
condition.put("status",1);
int rows = adminDao.deleteByMap(condition);
System.out.println("deleteByMap 受影响的行数："+rows);
}
6. SELECT
//查询
// 查询集合中多个主键值数据
List<T> selectBatchIds(@Param("coll") Collection<? extends Serializable> idList);
//根据Map条件查询
List<T> selectByMap(@Param("cm") Map<String, Object> columnMap);
//使用Wrapper对象作为查询条件
List<T> selectList(@Param("ew") Wrapper<T> queryWrapper);
//根据主键值查询
T selectById(Serializable id);
//根据Wrapper条件并进行分页
IPage<T> selectPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);
//记录查询数量
Integer selectCount(@Param("ew") Wrapper<T> queryWrapper);
//查询一个对象
T selectOne(@Param("ew") Wrapper<T> queryWrapper);
selectOne
sql: select * from admin where id =3
先创建Wrapper对象，添加查询条件， 调用selectOne()方法。 selectOne()的查询结果必须小于或等于一条记录，MP内部是调用的MyBatis的selectOne()方法，多于一个记录，系统会报错
@Test
public void selectOne(){
QueryWrapper<Admin> condition = new QueryWrapper<>();
condition.eq("id","3");
Admin res = adminDao.selectOne(condition);
System.out.println(res.toString());
}
selectById
sql: select * from admin where id =3
@Testpublic void testSelectAdmin(){
Admin admin = adminDao.selectById(3);
System.out.println("根据id查询结果："+admin.toString());
}
selectBatchIds
sql: select * from admin where id in (1,4)
@Test
public void selectBatchIds(){
List<Integer> idlist =new ArrayList<>();
idlist.add(1);
idlist.add(4);
List<Admin> res = adminDao.selectBatchIds(idlist);
System.out.println(res.size());
}
selectByMap
sql: select * from admin where username=“admin” and status=1
@Test
public void selectByMap(){
Map<String,Object> columnMap = new HashMap<>();
columnMap.put("username","admin");
columnMap.put("status",1);
List<Admin> res = adminDao.selectByMap(columnMap);
System.out.println(res.toString());
}
selectPage ：分页查询
需先配置分页bean
package com.xxx.xxx.config;
import com.baomidou.mybatisplus.core.injector.ISqlInjector;
import com.baomidou.mybatisplus.extension.injector.LogicSqlInjector;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MyBatisPlusConfiguration {
/**
* 开启mybatis-plus分页功能
* @return
*/
@Bean
public PaginationInterceptor paginationInterceptor() {
return new PaginationInterceptor();
}
}
selectPage(IPage page, Wrapper queryWrapper)
@Test
public void selectPageQueryWrapper(){
//new QueryWrapper() 条件构造器
//SELECT id,username,status,createdate FROM admin WHERE status=0 AND createDate BETWEEN ? AND ? AND status = ? LIMIT ?,?
//分页查询
IPage backIPage = adminDao.selectPage(new Page<Admin>(3,4),
new QueryWrapper<Admin>().between("createDate","2020-2-21","2020-2-23")
.eq("status",0));
System.out.println("当前页数数据条数"+backIPage.getSize());
System.out.println("总页数"+backIPage.getPages());
System.out.println("总数据条数"+backIPage.getTotal());
System.out.println("当前页数"+backIPage.getCurrent());
for (Admin admin:(List<Admin>)backIPage.getRecords()) {
System.out.println(admin.toString());
}
}
sql: SELECT id,username,status,createdate FROM admin WHERE status=0 LIMIT ?,?
@Test
public void selectPage(){
//分页查询 Page(2,3) 第二页，三条数据 ； null 无筛选条件
IPage backIPage = adminDao.selectPage(new Page<Admin>(2,3),null);
System.out.println("当前页数数据条数"+backIPage.getSize());
System.out.println("总页数"+backIPage.getPages());
System.out.println("总数据条数"+backIPage.getTotal());
System.out.println("当前页数"+backIPage.getCurrent());
List<Admin> list = backIPage.getRecords();
for (Admin a:list){
System.out.println(a.toString());
}
}
7. 逻辑删除
yml配置：
mybatis-plus:
global-config:
#逻辑删除配置（下面2个配置 还有配置一个bean，实体指定逻辑删除字段）
logic-delete-value: 0
logic-not-delete-value: 1
实体字段配置:
@TableLogic //逻辑删除注解
private Integer status;
bean配置:
package com.xxx.xxx.config;
import com.baomidou.mybatisplus.core.injector.ISqlInjector;
import com.baomidou.mybatisplus.extension.injector.LogicSqlInjector;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MyBatisPlusConfiguration {
/**
* 逻辑删除
* @return
*/
@Bean
public ISqlInjector sqlInjector() {
return new LogicSqlInjector();
}
}
执行效果:
//删除数据
@Test
public void deleteById(){
// sql : DELETE FROM admin WHERE id=?
//===>UPDATE admin SET status=1 WHERE id=? AND status=0
int rows = adminDao.deleteById(11);
System.out.println("deleteById结果："+rows);
}
五，条件构造器 EntityWrapper
-
Mybatis-Plust通过ENtityWrapper或者Condition来让用户自由的构建查询条件，简单便捷，没有额外的负担，能够有效提高开发效率
-
实体包装器，主要用于处理sql拼接，排序，实体参数查询等
-
注意：使用的是数据库阻断，不是java属性
-
条件参数说明:
https://mp.baomidou.com/guide/wrapper.html#abstractwrapper
以下示例中备注 * 代表表全字段名
between / eq:
@Test
public void selectPageQueryWrapper(){
//new QueryWrapper() 条件构造器
//分页查询
//SELECT id,username,status,createdate FROM admin WHERE createDate BETWEEN ? AND ? AND status = ?
IPage backIPage = adminDao.selectPage(new Page<Admin>(3,4),
new QueryWrapper<Admin>().between("createDate","2020-2-21","2020-2-23")
.eq("status",0));
//getRecords()得到的是所有行信息，不是分页的内容
for (Admin admin:(List<Admin>)backIPage.getRecords()) {
System.out.println(admin.toString());
}
}
or :
@Test
public void selectListQueryWrapper(){
//SELECT * FROM news WHERE status = ? AND title LIKE ? OR author LIKE ?
List<News> list = newsDao.selectList(
new QueryWrapper<News>()
.eq("status",1)
.like("title","上海")
.or()
.like("author","上海")
);
}
update:
@Test
public void updateQueryWrapper(){
//UPDATE news SET author=? WHERE status = ? AND title LIKE ?
News news =new News();
news.setId(1);//设置主键Id是没有用的，执行会根据QueryWrapper条件更新所有满足条件的行
news.setAuthor("上海1");
newsDao.update(news,
new QueryWrapper<News>()
.eq("status",0)
.like("title","上海")
);
}
delete:
@Test
public void deleteQueryWrapper(){
//DELETE FROM admin WHERE id = ?
adminDao.delete(
new QueryWrapper<Admin>()
.eq("id",28)
);
}
orderBy：
@Test
public void selectListOrderByQueryWrapper(){
//SELECT * FROM news WHERE status = ? ORDER BY readNum DESC
List<News> list = newsDao.selectList(
new QueryWrapper<News>()
.eq("status",1)
.orderByDesc("readNum")
);
}
六，ActiveRecord(活动记录)
AR基本CRUD
insert:
insert
@Test
public void insertAR(){
//INSERT INTO admin ( username, status, createdate ) VALUES ( ?, ?, ? )
Admin admin =new Admin();
admin.setStatus(0);
admin.setUsername("AR新增");
admin.setCreatedate(new Date());
boolean res = admin.insert();
if(res){
int newId = admin.getId();
System.out.println("AR新增加的ID是："+newId);
}else{
System.out.println("AR新增失败");
}
update：
updateById
@Test
public void updateAR(){
//UPDATE admin SET username=?, createdate=? WHERE id=?
Admin admin =new Admin();
admin.setId(29);
admin.setUsername("AR修改");
admin.setCreatedate(new Date());
boolean res = admin.updateById();
if(res){
System.out.println("AR修改成功");
}else{
System.out.println("AR修改失败");
}
}
select:
selectById(Serializable id)
@Test
public void selectByIdAR(){
//SELECT id,username,status,createdate FROM admin WHERE id=?
Admin admin = new Admin();
Admin res = admin.selectById(30);
System.out.println(res.toString());
}
selectAll()
@Test
public void selectAllAR(){
//SELECT id,username,status,createdate FROM admin
Admin admin = new Admin();
List<Admin> res = admin.selectAll();
for (Admin a : res){
System.out.println(a.toString());
}
}
selectList(Wrapper queryWrapper)
queryWrapper为null查询所有
@Test
public void selectList(){
//SELECT id,username,status,createdate FROM admin WHERE status = ?
Admin admin = new Admin();
List<Admin> res = admin.selectList(new QueryWrapper<Admin>().eq("status",1));
for (Admin a : res){
System.out.println(a.toString());
}
}
selectCount(Wrapper queryWrapper)
queryWrapper为null查询所有
@Test
public void selectCountAR(){
//SELECT COUNT( 1 ) FROM admin WHERE status = ?
Admin admin = new Admin();
int res = admin.selectCount(new QueryWrapper<Admin>().eq("status",1));
System.out.println("合计查询数："+res);
}
selectPage(IPage page, Wrapper queryWrapper) : AR分页
@Test
public void selectPageAR(){
//SELECT id,username,status,createdate FROM admin WHERE status=0 AND status = ? LIMIT ?,?
Admin admin = new Admin();
IPage<Admin> page = admin.selectPage(new Page<>(1,3),new QueryWrapper<Admin>().eq("status",0));
List<Admin> admins = page.getRecords();
System.out.println("当前页数数据条数"+page.getSize());
System.out.println("总页数"+page.getPages());
System.out.println("总数据条数"+page.getTotal());
System.out.println("当前页数"+page.getCurrent());
for (Admin a : admins){
System.out.println(a.toString());
}
}
detele
deleteById
@Test
public void deleteByIdAR(){
//DELETE FROM admin WHERE id=? 删除不存在的数据逻辑上是成功的返回也是true
Admin admin = new Admin();
boolean res = admin.deleteById(27);
System.out.println(res);
}
detele
@Test
public void deleteAR(){
//DELETE FROM admin WHERE id=? 删除不存在的数据逻辑上是成功的返回也是true
Admin admin = new Admin();
boolean res = admin.delete(new QueryWrapper<Admin>().eq("id",26));
System.out.println(res);
}