Video address: [Silicon Valley] MyBatisPlus tutorial (a set of fun with mybatis-plus)_哔哩哔哩_bilibili
- Shang Silicon Valley MyBatis-Plus Notes 01 [Introduction, Introductory Cases, Basic CRUD]
Shang Silicon Valley MyBatis-Plus Note 02【】
Shang Silicon Valley MyBatis-Plus Note 03【】
Shang Silicon Valley MyBatis-Plus Notes 04【】
Shang Silicon Valley MyBatis-Plus Note 05【】
Table of contents
1. Introduction to MyBatis-Plus
P01 [01-MyBatis-Plus Introduction] 03:18
P02 [02-MyBatis-Plus Features] 03:39
P03 [03-MyBatis-Plus supported database and framework structure] 03:00
P04 [04-Development environment of entry case] 01:51
P05 [05-Create test database and table] 01:21
P06 [06-Create Spring Boot project] 05:55
P07【07-Configure application.yml】08:16
P08 [08-Create entity class and simple use of lombok] 05:53
P09 [09-Create mapper interface and scan] 03:25
P11 [11-Join the log function] 03:22
P13【13-Test the new functions of BaseMapper】04:25
P14【14-Test the delete function of BaseMapper】08:22
P15 [15-Test the modification function of BaseMapper] 03:08
P16【16-Test the query function of BaseMapper】07:36
P17 [17-Test custom function] 05:35
P18【18-General Service Interface】07:23
P19【19-Test the total number of query records of general Service】03:13
P20【20-Testing the Batch Add Function of General Service】06:28
P21 [21-MyBatis-Plus's common annotation @TableName] 06:14
1. Introduction to MyBatis-Plus
MyBatis-Plus is an enhancement tool of MyBatis. Based on MyBatis, only enhancements are made without changes, and it is born to simplify development and improve efficiency. This video explains in detail from the features of MyBatis-Plus to excellent plug-ins, as well as the configuration of multiple data sources.
P01 [01-MyBatis-Plus Introduction] 03:18
Shang Silicon Valley MyBatis-Plus, Lecturer: Yang Bochao
Main content of the course
P02 [02-MyBatis-Plus Features] 03:39
MyBatis-plus official website: MyBatis-Plus
P03 [03-MyBatis-Plus supported database and framework structure] 03:00
2. Introductory case
P04 [04-Development environment of entry case] 01:51
Version:
- IDE: idea 2019.2
- JDK：JDK8+
- Build tool: maven 3.5.4
- MySQL version: MySQL 5.7
- Spring Boot：2.6.3
- MyBatis-Plus：3.5.1
P05 [05-Create test database and table] 01:21
bigint instead of int. MyBatisPlus uses the snowflake algorithm to generate id by default when inserting data . The length is relatively long, so bigint is used.
CREATE DATABASE `mybatis_plus` /*!40100 DEFAULT CHARACTER SET utf8mb4 */;
USE `mybatis_plus`;
CREATE TABLE `user` (
`id` BIGINT(20) NOT NULL COMMENT '主键ID',
`name` VARCHAR(30) DEFAULT NULL COMMENT '姓名',
`age` INT(11) DEFAULT NULL COMMENT '年龄',
`email` VARCHAR(50) DEFAULT NULL COMMENT '邮箱',
PRIMARY KEY (`id`)
) ENGINE=INNODB DEFAULT CHARSET=utf8;
INSERT INTO USER (id, NAME, age, email) VALUES
(1, 'Jone', 18, '[email protected]'),
(2, 'Jack', 20, '[email protected]'),
(3, 'Tom', 28, '[email protected]'),
(4, 'Sandy', 21, '[email protected]'),
(5, 'Billie', 24, '[email protected]');P06 [06-Create Spring Boot project] 05:55
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.3</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.atguigu</groupId>
<artifactId>mybatisplus</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>mybatisplus</name>
<description>mybatisplus</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!--mybatis-plus启动器-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.5.1</version>
</dependency>
<!--lombok用于简化实体类开发-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<!--mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!--
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-generator</artifactId>
<version>3.5.1</version>
</dependency>
<dependency>
<groupId>org.freemarker</groupId>
<artifactId>freemarker</artifactId>
<version>2.3.31</version>
</dependency>-->
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>P07【07-Configure application.yml】08:16
application.properties
#spring.datasource.type=com.zaxxer.hikari.HikariDataSource
#spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driverapplication.yml
spring:
# 配置数据源信息
datasource:
# 配置数据源类型
type: com.zaxxer.hikari.HikariDataSource
# 配置连接数据库信息
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/mybatis_plus?characterEncoding=utf8&useSSL=false
username: root
password: 123456P08 [08-Create entity class and simple use of lombok] 05:53
Data annotation: equivalent to no-argument construction, getter, setter, equals, hashCode, toString methods.
P09 [09-Create mapper interface and scan] 03:25
- BaseMapper is the template mapper provided by MyBatis-Plus, which contains basic CRUD methods, and the generic type is the entity type of the operation.
- @MapperScan("com.atguigu.mybatisplus.mapper") //Used to scan the package where the mapper interface is located, and scan the mapper interface under the specified package
P10【10-Test】07:22
IDEA reports an error at userMapper because the injected object cannot be found, because the class is dynamically created, but the program can be executed correctly.
In order to avoid error reporting, you can add the @Repository annotation to the mapper interface.
package com.atguigu.mybatisplus;
import com.atguigu.mybatisplus.mapper.UserMapper;
import com.atguigu.mybatisplus.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.List;
@SpringBootTest
public class MybatisPlusTest {
@Autowired
private UserMapper userMapper;//正常报错，不影响运行
//userMapper动态生成的代理类交给了ioc容器管理
@Test
public void testSelectList() {
//通过条件构造器查询一个list集合，若没有条件，则可以设置null为参数.
List<User> list = userMapper.selectList(null);
list.forEach(System.out::println);
}
}P11 [11-Join the log function] 03:22
3. Basic CRUD
P12【12-BaseMapper】04:37
BaseMapper.java , the basic CRUD in MyBatis-Plus has been implemented in the built-in BaseMapper, we can use it directly, the interface is as follows:
/*
* Copyright (c) 2011-2022, baomidou ([email protected]).
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.baomidou.mybatisplus.core.mapper;
import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;
import com.baomidou.mybatisplus.core.toolkit.Constants;
import com.baomidou.mybatisplus.core.toolkit.ExceptionUtils;
import org.apache.ibatis.annotations.Param;
import java.io.Serializable;
import java.util.Collection;
import java.util.List;
import java.util.Map;
/*
_ _ /_ _ _/_. ____ / _
/ / //_//_//_|/ /_\ /_///_/_\ Talk is cheap. Show me the code.
_/ /
*/
/**
* Mapper 继承该接口后，无需编写 mapper.xml 文件，即可获得CRUD功能
* <p>这个 Mapper 支持 id 泛型</p>
*
* @author hubin
* @since 2016-01-23
*/
public interface BaseMapper<T> extends Mapper<T> {
/**
* 插入一条记录
*
* @param entity 实体对象
*/
int insert(T entity);
/**
* 根据 ID 删除
*
* @param id 主键ID
*/
int deleteById(Serializable id);
/**
* 根据实体(ID)删除
*
* @param entity 实体对象
* @since 3.4.4
*/
int deleteById(T entity);
/**
* 根据 columnMap 条件，删除记录
*
* @param columnMap 表字段 map 对象
*/
int deleteByMap(@Param(Constants.COLUMN_MAP) Map<String, Object> columnMap);
/**
* 根据 entity 条件，删除记录
*
* @param queryWrapper 实体对象封装操作类（可以为 null,里面的 entity 用于生成 where 语句）
*/
int delete(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
/**
* 删除（根据ID或实体 批量删除）
*
* @param idList 主键ID列表或实体列表(不能为 null 以及 empty)
*/
int deleteBatchIds(@Param(Constants.COLLECTION) Collection<?> idList);
/**
* 根据 ID 修改
*
* @param entity 实体对象
*/
int updateById(@Param(Constants.ENTITY) T entity);
/**
* 根据 whereEntity 条件，更新记录
*
* @param entity 实体对象 (set 条件值,可以为 null)
* @param updateWrapper 实体对象封装操作类（可以为 null,里面的 entity 用于生成 where 语句）
*/
int update(@Param(Constants.ENTITY) T entity, @Param(Constants.WRAPPER) Wrapper<T> updateWrapper);
/**
* 根据 ID 查询
*
* @param id 主键ID
*/
T selectById(Serializable id);
/**
* 查询（根据ID 批量查询）
*
* @param idList 主键ID列表(不能为 null 以及 empty)
*/
List<T> selectBatchIds(@Param(Constants.COLLECTION) Collection<? extends Serializable> idList);
/**
* 查询（根据 columnMap 条件）
*
* @param columnMap 表字段 map 对象
*/
List<T> selectByMap(@Param(Constants.COLUMN_MAP) Map<String, Object> columnMap);
/**
* 根据 entity 条件，查询一条记录
* <p>查询一条记录，例如 qw.last("limit 1") 限制取一条记录, 注意：多条数据会报异常</p>
*
* @param queryWrapper 实体对象封装操作类（可以为 null）
*/
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;
}
/**
* 根据 Wrapper 条件，判断是否存在记录
*
* @param queryWrapper 实体对象封装操作类
* @return
*/
default boolean exists(Wrapper<T> queryWrapper) {
Long count = this.selectCount(queryWrapper);
return null != count && count > 0;
}
/**
* 根据 Wrapper 条件，查询总记录数
*
* @param queryWrapper 实体对象封装操作类（可以为 null）
*/
Long selectCount(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
/**
* 根据 entity 条件，查询全部记录
*
* @param queryWrapper 实体对象封装操作类（可以为 null）
*/
List<T> selectList(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
/**
* 根据 Wrapper 条件，查询全部记录
*
* @param queryWrapper 实体对象封装操作类（可以为 null）
*/
List<Map<String, Object>> selectMaps(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
/**
* 根据 Wrapper 条件，查询全部记录
* <p>注意： 只返回第一个字段的值</p>
*
* @param queryWrapper 实体对象封装操作类（可以为 null）
*/
List<Object> selectObjs(@Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
/**
* 根据 entity 条件，查询全部记录（并翻页）
*
* @param page 分页查询条件（可以为 RowBounds.DEFAULT）
* @param queryWrapper 实体对象封装操作类（可以为 null）
*/
<P extends IPage<T>> P selectPage(P page, @Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
/**
* 根据 Wrapper 条件，查询全部记录（并翻页）
*
* @param page 分页查询条件
* @param queryWrapper 实体对象封装操作类
*/
<P extends IPage<Map<String, Object>>> P selectMapsPage(P page, @Param(Constants.WRAPPER) Wrapper<T> queryWrapper);
}P13【13-Test the new functions of BaseMapper】04:25
@Test
public void testInsert() {
//实现新增用户信息
//INSERT INTO user ( id, name, age, email ) VALUES ( ?, ?, ?, ? )
User user = new User();
//user.setId(100L);
user.setName("张三");
user.setAge(23);
user.setEmail("[email protected]");
int result = userMapper.insert(user);
System.out.println("result:" + result);
System.out.println("id:" + user.getId());
}P14【14-Test the delete function of BaseMapper】08:22
@Test
public void testDelete() {
//1、通过id删除用户信息
//DELETE FROM user WHERE id=?
// int result = userMapper.deleteById(1659014646172069890L);
// System.out.println("result：" + result);
//2、根据map集合中所设置的条件删除用户信息
//DELETE FROM user WHERE name = ? AND age = ?
// Map<String, Object> map = new HashMap<>();
// map.put("name", "张三");
// map.put("age", 23);
// int result = userMapper.deleteByMap(map);
// System.out.println("result：" + result);
//3、通过多个id实现批量删除
//DELETE FROM user WHERE id IN ( ? , ? , ? )
List<Long> list = Arrays.asList(1L, 2L, 3L);
int result = userMapper.deleteBatchIds(list);
System.out.println("result：" + result);
}P15 [15-Test the modification function of BaseMapper] 03:08
@Test
public void testUpdate() {
//修改用户信息
//UPDATE user SET name=?, email=? WHERE id=?
User user = new User();
user.setId(4L);
user.setName("李四");
user.setEmail("[email protected]");
int result = userMapper.updateById(user);
System.out.println("result：" + result);
}P16【16-Test the query function of BaseMapper】07:36
@Test
public void testSelect() {
//通过id查询用户信息
//SELECT id,name,age,email FROM user WHERE id=?
User user = userMapper.selectById(1L);
System.out.println(user);
//根据多个id查询多个用户信息
//SELECT id,name,age,email FROM user WHERE id IN ( ? , ? , ? )
List<Long> list = Arrays.asList(1L, 2L, 3L);
List<User> users = userMapper.selectBatchIds(list);
users.forEach(System.out::println);
//根据map集合中的条件查询用户信息
//SELECT id,name,age,email FROM user WHERE name = ? AND age = ?
Map<String, Object> map = new HashMap<>();
map.put("name", "Jack");
map.put("age", 20);
List<User> users = userMapper.selectByMap(map);
users.forEach(System.out::println);
//查询所有数据
//SELECT id,name,age,email FROM user
List<User> users = userMapper.selectList(null);
users.forEach(System.out::println);
Map<String, Object> map = userMapper.selectMapById(1L);
System.out.println(map);
}P17 [17-Test custom function] 05:35
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.atguigu.mybatisplus.mapper.UserMapper">
<!--Map<String, Object> selectMapById(Long id);-->
<select id="selectMapById" resultType="map">
select id, name, age, email
from user
where id = #{id}
</select>
</mapper>P18【18-General Service Interface】07:23
Ctrl+N: Ctrl+N searches for classes by name, and searches to view classes.
package com.atguigu.mybatisplus.service;
import com.atguigu.mybatisplus.pojo.User;
import com.baomidou.mybatisplus.extension.service.IService;
public interface UserService extends IService<User> {
}package com.atguigu.mybatisplus.service.impl;
import com.atguigu.mybatisplus.mapper.UserMapper;
import com.atguigu.mybatisplus.pojo.User;
import com.atguigu.mybatisplus.service.UserService;
import com.baomidou.mybatisplus.extension.service.IService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
}P19【19-Test the total number of query records of general Service】03:13
package com.atguigu.mybatisplus;
import com.atguigu.mybatisplus.service.UserService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
public class MyBatisPlusServiceTest {
@Autowired
private UserService userService;
@Test
public void testGetCount() {
//查询总记录数
//SELECT COUNT( * ) FROM user
long count = userService.count();
System.out.println("总记录数：" + count);
}
}P20【20-Testing the Batch Add Function of General Service】06:28
IDEA provides CTRL+ALT+V for this line to quickly and automatically generate variables according to the variable type.
package com.atguigu.mybatisplus;
import com.atguigu.mybatisplus.pojo.User;
import com.atguigu.mybatisplus.service.UserService;
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.List;
@SpringBootTest
public class MyBatisPlusServiceTest {
@Autowired
private UserService userService;
@Test
public void testGetCount() {
//查询总记录数
//SELECT COUNT( * ) FROM user
long count = userService.count();
System.out.println("总记录数：" + count);
}
@Test
public void testInsertMore() {
//批量添加
//INSERT INTO user ( id, name, age ) VALUES ( ?, ?, ? )
List<User> list = new ArrayList<>();
for (int i = 1; i < 10; i++) {
User user = new User();
user.setId(Integer.toUnsignedLong(i * 10));
user.setName("abc" + i);
user.setAge(20 + i);
list.add(user);
}
boolean b = userService.saveBatch(list);
System.out.println(b);
}
}Four, common annotations
P21 [21-MyBatis-Plus's common annotation @TableName] 06:14
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