MyBatisPlus学习记录

MyBatisPlus(简称MP）是基于MyBatis框架基础上开发的增强型工具，旨在简化开发、提高效率

MyBatisPlus简介

入门案例

创建新模块，选择Spring初始化，并配置模块相关基础信息
选择当前模块需要使用的技术集（仅选择MySQL Driver)
手动添加mp起步依赖

    <dependencies>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.16</version>
        </dependency>

由于mp并未被收录到idea的系统内置配置，无法直接选择加入

设置Jdbc参数( application. yml)

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/db1
    username: root
    password: "031006"

制作实体类与表结构（类名与表名对应，属性名与字段名对应)

package com.example.domain;

public class User {
    
    

    private Long id;
    private String name;
    private String password;
    private Integer age;
    private String tel;

    @Override
    public String toString() {
    
    
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", password='" + password + '\'' +
                ", age=" + age +
                ", tel='" + tel + '\'' +
                '}';
    }

    public Long getId() {
    
    
        return id;
    }

    public void setId(Long id) {
    
    
        this.id = id;
    }

    public String getName() {
    
    
        return name;
    }

    public void setName(String name) {
    
    
        this.name = name;
    }

    public String getPassword() {
    
    
        return password;
    }

    public void setPassword(String password) {
    
    
        this.password = password;
    }

    public Integer getAge() {
    
    
        return age;
    }

    public void setAge(Integer age) {
    
    
        this.age = age;
    }

    public String getTel() {
    
    
        return tel;
    }

    public void setTel(String tel) {
    
    
        this.tel = tel;
    }
}

定义数据接口，继承BaseMapper<User>

package com.example.dao;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.domain.User;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface UserDao extends BaseMapper<User> {
    
    
}

测试类中注入dao接口，测试功能

package com.example;

import com.example.dao.UserDao;
import com.example.domain.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
class MybatisplusApplicationTests {
    
    

    @Autowired
    private UserDao userDao;

    @Test
    void testGetAll() {
    
    
        List<User> users = userDao.selectList(null);
        System.out.println(users);
    }

}

运行结果为

[User{id=1, name='Tom', password='tom123', age=18, tel='181633335556'}, User{id=2, name='Jerry', password='jerry666', age=17, tel='19533336666'}, User{id=3, name='Ben', password='ben555', age=20, tel='13788889999'}, User{id=4, name='王小明', password='wxm123456', age=19, tel='19999997787'}]

MyBatisPlus概述

MyBatisPlus(简称MP）是基于MyBatis框架基础上开发的增强型工具，旨在简化开发、提高效率

官网: MyBatis-Plus MyBatis-Plus (baomidou.com)

特性

无侵入：只做增强不做改变，引入它不会对现有工程产生影响，如丝般顺滑
强大的 CRUD 操作：内置通用 Mapper、通用 Service，仅仅通过少量配置即可实现单表大部分 CRUD 操作，更有强大的条件构造器，满足各类使用需求
支持 Lambda 形式调用：通过 Lambda 表达式，方便的编写各类查询条件，无需再担心字段写错
支持主键自动生成：支持多达 4 种主键策略（内含分布式唯一 ID 生成器 - Sequence），可自由配置，完美解决主键问题
内置分页插件：基于 MyBatis 物理分页，开发者无需关心具体操作，配置好插件之后，写分页等同于普通 List 查询
…

标准数据层开发

标准数据层CRUD功能

功能	MP接口
新增	int insert(T t)
删除	int deleteById(Serializable id)
修改	int UpdateById(T t)
根据id查询	T selectById(Serializable id)
查询全部	List<T> selectList()
分页查询	IPage<T> selectPage(Ipage<T> page)
按条件查询	IPage<T> selectPage(Wrapper<T> queryWrapper)

package com.example;

import com.example.dao.UserDao;
import com.example.domain.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
class MybatisplusApplicationTests {
    
    

    @Autowired
    private UserDao userDao;

    @Test
    void testInsert() {
    
    
        User user = new User();
        user.setAge(18);
        user.setName("Faiz");
        user.setTel("18155555555");
        user.setPassword("faiz555");
        userDao.insert(user);
    }

    @Test
    void testDelete() {
    
    
        userDao.deleteById(1685579916861468673L);
    }

    @Test
    void testUpdate() {
    
    
        User user = new User();
        // 只修改set好的字段
        user.setAge(18);
        user.setName("Faiz");

        user.setId(4L);

        userDao.updateById(user);
    }

    @Test
    void testGetById() {
    
    
        User user = userDao.selectById(2L);
        System.out.println(user);
    }

    @Test
    void testGetAll() {
    
    
        List<User> users = userDao.selectList(null);
        System.out.println(users);
    }

}

lombok

Lombok，一个Java类库，提供了一组注解，简化PO30实体类开发

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>

    </dependencies>

package com.example.domain;

import lombok.*;

// lombok

//@Setter
//@Getter
//@ToString
//@NoArgsConstructor
//@AllArgsConstructor
@Data
public class User {
    
    

    private Long id;
    private String name;
    private String password;
    private Integer age;
    private String tel;

}

常用注解:@Data

为当前实体类在编译期设置对应的get/set方法，toString方法， hashCode方法，equals方法等

分页功能

设置分页拦截器作为Spring管理的bean

package com.example.config;

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MpConfig {
    
    
    @Bean
    public MybatisPlusInterceptor mpIntercepter() {
    
    
        // 1.定义Mp拦截器
        MybatisPlusInterceptor mpIntercepter = new MybatisPlusInterceptor();
        // 2.添加具体的拦截器
        mpIntercepter.addInnerInterceptor(new PaginationInnerInterceptor());
        return mpIntercepter;
    }
}

执行分页查询

    @Test
    void testGetByPage() {
    
    
        IPage page = new Page(1,2);
        userDao.selectPage(page,null);
        System.out.println("当前页码值："+page.getCurrent());
        System.out.println("每页显示数："+page.getSize());
        System.out.println("一共多少页："+page.getPages());
        System.out.println("一共多少条数据："+page.getTotal());
        System.out.println("数据："+page.getRecords());
    }

运行结果为：

当前页码值：1
每页显示数：2
一共多少页：2
一共多少条数据：4
数据：[User(id=1, name=Tom, password=tom123, age=18, tel=181633335556), User(id=2, name=Jerry, password=jerry666, age=17, tel=19533336666)]

开启MP的日志（输出到控制台）

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/db1
    username: root
    password: "031006"

# 开启MP的日志（输出到控制台）
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

DQL编程控制

条件查询方式

MyBatisPlus将书写复杂的SQL查询条件进行了封装，使用编程的形式完成查询条件的组合

    @Test
    void testGetAll() {
    
    
        // 方式一，按条件查询
        QueryWrapper wrapper = new QueryWrapper();
        // age < 18
        wrapper.lt("age",18);
        List<User> users1 = userDao.selectList(wrapper);
        System.out.println(users1);

        // 方式二，lambda格式按条件查询
        QueryWrapper<User> wrapper2 = new QueryWrapper<>();
        // age < 18
        wrapper2.lambda().lt(User::getAge,18);
        List<User> users2 = userDao.selectList(wrapper);
        System.out.println(users2);

        // 方式三，lambda格式按条件查询
        LambdaQueryWrapper<User> lambdaQueryWrapper1 = new LambdaQueryWrapper<>();
        // age < 18
        lambdaQueryWrapper1.lt(User::getAge,18);
        List<User> users = userDao.selectList(lambdaQueryWrapper1);
        System.out.println(users);

        LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
//        // age < 20
//        lambdaQueryWrapper.lt(User::getAge,20);
//        // age > 17
//        lambdaQueryWrapper.gt(User::getAge,17);
        // age < 20 && age > 17
//        lambdaQueryWrapper.lt(User::getAge,20).gt(User::getAge,17);
        // age < 18 || age > 20
        lambdaQueryWrapper.lt(User::getAge,18).or().gt(User::getAge,20);
        List<User> users3 = userDao.selectList(lambdaQueryWrapper);
        System.out.println(users3);
    }

null值处理

方式一：用if
方式二：

        UserQuery userQuery = new UserQuery();
//        userQuery.setAge(20);
        userQuery.setAge2(17);

        LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
        // 先判断第一个条件是否为true,为true则连接当前条件
        // age < 20
        lambdaQueryWrapper.lt(null != userQuery.getAge(),User::getAge,userQuery.getAge());
        // age > 17
        lambdaQueryWrapper.gt(null != userQuery.getAge2(),User::getAge,userQuery.getAge2());
        List<User> users = userDao.selectList(lambdaQueryWrapper);
        System.out.println(users);

查询投影

查询结果包含模型类中部分属性

        // 查询投影

        // 方式一
        LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
        lambdaQueryWrapper.select(User::getId,User::getName,User::getAge);
        List<User> users1 = userDao.selectList(lambdaQueryWrapper);

        // 方式二
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper.select("id","name","age");
        List<User> users2 = userDao.selectList(queryWrapper);

        System.out.println(users1);
        System.out.println(users2);

查询结果包含模型类中未定义的属性

        // 查询投影
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper.select("count(*) as count,age");
        queryWrapper.groupBy("age");
        List<Map<String, Object>> users = userDao.selectMaps(queryWrapper);
        System.out.println(users);

查询条件设定

范围匹配(> 、= . between)
模糊匹配(like)
空判定(null)
包含性匹配(in)
分组(group)
排序(order)
…

eq匹配

        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();

        lqw.eq(User::getName,"Faiz");
        lqw.eq(User::getPassword,"wxm123456");

//        List<User> users = userDao.selectList(lqw);
//        System.out.println(users);
        User user = userDao.selectOne(lqw);
        System.out.println(user);

范围查询

        LambdaQueryWrapper<User> lqw = new LambdaQueryWrapper<>();
        // 范围查询 lt,le,gt,ge,eq,between
        // 18 <= age <20
        lqw.between(User::getAge,18,20);

        List<User> users = userDao.selectList(lqw);
        System.out.println(users);

模糊匹配

// 模糊匹配 like

        // %e%(String)
//        lqw.like(User::getName,"e");
//        // [User(id=2, name=Jerry, password=jerry666, age=17, tel=19533336666), User(id=3, name=Ben, password=ben555, age=20, tel=13788889999), User(id=6, name=Decade, password=wxmmmmm, age=19, tel=16666666666)]
        // %e(String)
        lqw.likeLeft(User::getName,"e");
        // [User(id=6, name=Decade, password=wxmmmmm, age=19, tel=16666666666)]

        // e%(String)
//        lqw.likeRight(User::getName,"e");
        // []

        List<User> users = userDao.selectList(lqw);
        System.out.println(users);

字段映射与表名映射

问题一:表字段与编码属性设计不同步

名称:@TableField
类型:属性注解
位置:模型类属性定义上方
作用:设置当前属性对应的数据库表中的字段关系

范例:

public class User {
      
      
	@TableField(value="pwd")
    private String password;
}

相关属性
- value(默认):设置数据库表字段名称

问题二:编码中添加了数据库中未定义的属性

名称:@TableField
类型:属性注解
位置:模型类属性定义上方
作用:设置当前属性对应的数据库表中的字段关系

范例:

public class User {
      
      
	@TableField(exist = false)
    private Integer online;
}

相关属性
- value:设置数据库表字段名称
- exist:设置属性在数据库表字段中是否存在，默认为true。此属性无法与value合并使用

问题三:采用默认查询开放了更多的字段查看权限

名称:@TableField
类型:属性注解
位置:模型类属性定义上方
作用:设置当前属性对应的数据库表中的字段关系

范例:

public class User {
      
      
	@TableField(value="pwd",select = false)
    private String password;
}

相关属性
- value:设置数据库表字段名称
- exist:设置属性在数据库表字段中是否存在，默认为true。此属性无法与value合并使用
- select:设置属性是否参与查询，此属性与select()映射配置不冲突

问题四:表名与编码开发设计不同步

名称:@TableName
类型:类注解
位置:模型类定义上方
作用:设置当前类对应与数据库表关系

范例:

@TableName("tbl_user")
public class User {
      
      
	private Long id;
}

相关属性
- value:设置数据库表名称

package com.example.domain;

import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.*;

// lombok

//@Setter
//@Getter
//@ToString
//@NoArgsConstructor
//@AllArgsConstructor
@Data
@TableName("tbl_user")
public class User {
    
    

    private Long id;
    private String name;
    @TableField(value = "pwd",select = false)
    private String password;
    private Integer age;
    private String tel;
    @TableField(exist = false)
    private Integer online;
}

DML编程控制

Insert

id生成策略

不同的表应用不同的id生成策略

日志:自增（ 1,2,3,4，…
购物订单:特殊规则（ FQ23948AK3843)
外卖单:关联地区日期等信息（ 10 04 20200314 34 91)
关系表:可省略id
…

id生成策略控制

名称:@TableId
类型:属性注解
位置:模型类中用于表示主键的属性定义上方
作用:设置当前类中主键属性的生成策略·范例:

public class User {
    
    
	@TableId(type = IdType.AUTO)
    private Long id;
}

相关属性
- value:设置数据库主键名称
- type:设置主键属性的生成策略，值参照IdType枚举值
AUTO(0)∶使用数据库id自增策略控制id生成
NONE(1):不设置id生成策略
INPUT(2):用户手工输入id
ASSIGN_ID(3):雪花算法生成id（可兼容数值型与字符串型)
ASSIGN_UUID(4):以UUID生成算法作为id生成策略

package com.example.domain;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.*;

// lombok

//@Setter
//@Getter
//@ToString
//@NoArgsConstructor
//@AllArgsConstructor
@Data
@TableName("tbl_user")
public class User {
    
    

    // 使用数据库定义的
//    @TableId(type = IdType.AUTO)
    // 自己定义  user.setId(555L);
//    @TableId(type = IdType.INPUT)
    // 雪花算法
    @TableId(type = IdType.ASSIGN_ID)
    private Long id;
    private String name;
    @TableField(value = "pwd",select = false)
    private String password;
    private Integer age;
    private String tel;
    @TableField(exist = false)
    private Integer online;
}

id生成策略全局配置

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/db1
    username: root
    password: "031006"
  main:
    banner-mode: off

# 开启MP的日志（输出到控制台）
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

  global-config:
    banner: false
    db-config:
      id-type: assign_id
      table-prefix: tbl_

Delete

多记录操作

    @Test
    void testDelete() {
    
    
//        userDao.deleteById(1685579916861468673L);
        List<Long> list = new ArrayList<>();
        list.add(1685940449313812482L);
        list.add(1685941696037003266L);
        list.add(1685942172673523714L);
        userDao.deleteBatchIds(list);
    }

逻辑删除

删除操作业务问题:业务数据从数据库中丢弃
逻辑删除:为数据设置是否可用状态字段，删除时设置状态字段为不可用状态，数据保留在数据库中

@Data
//@TableName("tbl_user")
public class User {
    
    

    // 使用数据库定义的
//    @TableId(type = IdType.AUTO)
    // 自己定义  user.setId(555L);
//    @TableId(type = IdType.INPUT)
    // 雪花算法
//    @TableId(type = IdType.ASSIGN_ID)
    private Long id;
    private String name;
    @TableField(value = "pwd",select = false)
    private String password;
    private Integer age;
    private String tel;
    @TableField(exist = false)
    private Integer online;

    // 逻辑删除字段,标记当前记录是否被删除
    @TableLogic(value = "0",delval = "1")
    private Integer deleted;
}

    @Test
    void testDelete() {
        userDao.deleteById(1);
//        List<Long> list = new ArrayList<>();
//        list.add(1685940449313812482L);
//        list.add(1685941696037003266L);
//        list.add(1685942172673523714L);
//        userDao.deleteBatchIds(list);
    }

运行结果为：

Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
Registered plugin: 'com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor@4277127c'
Property 'mapperLocations' was not specified.
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6c075e9d] was not registered for synchronization because synchronization is not active
JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@2c06b113] will not be managed by Spring
==>  Preparing: UPDATE tbl_user SET deleted=1 WHERE id=? AND deleted=0
==> Parameters: 1(Integer)
<==    Updates: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6c075e9d]

查询操作

    @Test
    void testDelete() {
    
    
//        userDao.deleteById(1);
        userDao.selectList(null);
//        List<Long> list = new ArrayList<>();
//        list.add(1685940449313812482L);
//        list.add(1685941696037003266L);
//        list.add(1685942172673523714L);
//        userDao.deleteBatchIds(list);
    }

结果为

Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
Registered plugin: 'com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor@20f6f88c'
Property 'mapperLocations' was not specified.
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@8fcc534] was not registered for synchronization because synchronization is not active
JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@16681017] will not be managed by Spring
==>  Preparing: SELECT id,name,age,tel,deleted FROM tbl_user WHERE deleted=0
==> Parameters: 
<==    Columns: id, name, age, tel, deleted
<==        Row: 2, Jerry, 17, 19533336666, 0
<==        Row: 3, Ben, 20, 13788889999, 0
<==        Row: 4, Faiz, 18, 19999997787, 0
<==        Row: 5, Build, 21, 17569932244, 0
<==        Row: 6, Decade, 19, 16666666666, 0
<==        Row: 7, Exaid, 18, 19155555555, 0
<==        Row: 111, Exaid, 18, 19155555555, 0
<==        Row: 555, Exaid, 18, 19155555555, 0
<==      Total: 8
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@8fcc534]

注意：

==> Preparing: SELECT id,name,age,tel,deleted FROM tbl_user WHERE deleted=0

配置的方式

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/db1
    username: root
    password: "031006"
  main:
    banner-mode: off

# 开启MP的日志（输出到控制台）
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

  global-config:
    banner: false
    db-config:
      id-type: assign_id
      table-prefix: tbl_
      logic-delete-field: deleted
      logic-not-delete-value: 0
      logic-delete-value: 1

update

乐观锁

数据库表中添加锁标记字段
实体类中添加对应字段，并设定当前字段为逻辑删除标记字段

@Data
//@TableName("tbl_user")
public class User {
    
    

    // 使用数据库定义的
//    @TableId(type = IdType.AUTO)
    // 自己定义  user.setId(555L);
//    @TableId(type = IdType.INPUT)
    // 雪花算法
//    @TableId(type = IdType.ASSIGN_ID)
    private Long id;
    private String name;
    @TableField(value = "pwd",select = false)
    private String password;
    private Integer age;
    private String tel;
    @TableField(exist = false)
    private Integer online;

    // 逻辑删除字段,标记当前记录是否被删除
//    @TableLogic(value = "0",delval = "1")
    private Integer deleted;

    @Version
    private Integer version;
}

配置乐观锁拦截器实现锁机制对应的动态SQL语句拼装

@Configuration
public class MpConfig {
    
    
    @Bean
    public MybatisPlusInterceptor mpIntercepter() {
    
    
        // 1.定义Mp拦截器
        MybatisPlusInterceptor mpIntercepter = new MybatisPlusInterceptor();
        // 2.添加具体的拦截器
        mpIntercepter.addInnerInterceptor(new PaginationInnerInterceptor());
        // 3.添加乐观锁的拦截器
        mpIntercepter.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
        return mpIntercepter;
    }
}

使用乐观锁机制在修改前必须先获取到对应数据的verion方可正常进行

    @Test
    void testUpdate() {
    
    
//        User user = new User();
//        // 只修改set好的字段
//        user.setAge(18);
//        user.setName("Faiz");
//        user.setId(4L);
//        user.setPassword("fa5555");
//        user.setVersion(1);
//        userDao.updateById(user);

//        //1.先通过要修改的数id将当前数据查询出来
//        User user = userDao.selectById(4L);
//        //2.将要修改的属性逐一设置进去
//        user.setName("Faiz555");
//        userDao.updateById(user);

        User user = userDao.selectById(4L);  // version=3,name=Faiz555
        User user2 = userDao.selectById(4L);  // version=3,name=Faiz555

        user2.setName("Faiz666");
        userDao.updateById(user2);   // version=4,name=Faiz666

        user.setName("Faiz777");
        userDao.updateById(user);

        // 最终：version=4,name=Faiz666
    }

运行结果：

Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
Registered plugin: 'com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor@5b7c8930'
Property 'mapperLocations' was not specified.
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@4a642e4b] was not registered for synchronization because synchronization is not active
JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@32ab408e] will not be managed by Spring
==>  Preparing: SELECT id,name,age,tel,deleted,version FROM tbl_user WHERE id=? AND deleted=0
==> Parameters: 4(Long)
<==    Columns: id, name, age, tel, deleted, version
<==        Row: 4, Faiz555, 18, 19999997787, 0, 3
<==      Total: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@4a642e4b]
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7b297740] was not registered for synchronization because synchronization is not active
JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@32ab408e] will not be managed by Spring
==>  Preparing: SELECT id,name,age,tel,deleted,version FROM tbl_user WHERE id=? AND deleted=0
==> Parameters: 4(Long)
<==    Columns: id, name, age, tel, deleted, version
<==        Row: 4, Faiz555, 18, 19999997787, 0, 3
<==      Total: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7b297740]
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6e3dd5ce] was not registered for synchronization because synchronization is not active
JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@32ab408e] will not be managed by Spring
==>  Preparing: UPDATE tbl_user SET name=?, age=?, tel=?, version=? WHERE id=? AND version=? AND deleted=0
==> Parameters: Faiz666(String), 18(Integer), 19999997787(String), 4(Integer), 4(Long), 3(Integer)
<==    Updates: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6e3dd5ce]
Creating a new SqlSession
SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7d7ceca8] was not registered for synchronization because synchronization is not active
JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@32ab408e] will not be managed by Spring
==>  Preparing: UPDATE tbl_user SET name=?, age=?, tel=?, version=? WHERE id=? AND version=? AND deleted=0
==> Parameters: Faiz777(String), 18(Integer), 19999997787(String), 4(Integer), 4(Long), 3(Integer)
<==    Updates: 0
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7d7ceca8]

Process finished with exit code 0

快速开发

代码生成器

模板:MyBatisPlus提供

数据库相关配置:读取数据库获取信息

开发者自定义配置:手工配置

导入依赖

<?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>2.5.1</version>
    </parent>
    <groupId>com.itheima</groupId>
    <artifactId>mybatisplus_04_generator</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <!--spring webmvc-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--mybatisplus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>

        <!--druid-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.16</version>
        </dependency>

        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

        <!--test-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>

        <!--代码生成器-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>3.4.1</version>
        </dependency>

        <!--velocity模板引擎-->
        <dependency>
            <groupId>org.apache.velocity</groupId>
            <artifactId>velocity-engine-core</artifactId>
            <version>2.3</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

创建代码生成器对象，执行生成代码操作

public class CodeGenerator {
    
    
    public static void main(String[] args) {
    
    
        //1.获取代码生成器的对象
        AutoGenerator autoGenerator = new AutoGenerator();

        //设置数据库相关配置
        DataSourceConfig dataSource = new DataSourceConfig();
        dataSource.setDriverName("com.mysql.cj.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://localhost:3306/db1?serverTimezone=UTC");
        dataSource.setUsername("root");
        dataSource.setPassword("031006");
        autoGenerator.setDataSource(dataSource);

        //设置全局配置
        GlobalConfig globalConfig = new GlobalConfig();
        globalConfig.setOutputDir(System.getProperty("user.dir")+"/src/main/java");    //设置代码生成位置
        globalConfig.setOpen(false);    //设置生成完毕后是否打开生成代码所在的目录
        globalConfig.setAuthor("xlr");    //设置作者
        globalConfig.setFileOverride(true);     //设置是否覆盖原始生成的文件
        globalConfig.setMapperName("%sDao");    //设置数据层接口名，%s为占位符，指代模块名称
        globalConfig.setIdType(IdType.ASSIGN_ID);   //设置Id生成策略
        autoGenerator.setGlobalConfig(globalConfig);

        //设置包名相关配置
        PackageConfig packageInfo = new PackageConfig();
        packageInfo.setParent("com.example");   //设置生成的包名，与代码所在位置不冲突，二者叠加组成完整路径
        packageInfo.setEntity("domain");    //设置实体类包名
        packageInfo.setMapper("dao");   //设置数据层包名
        autoGenerator.setPackageInfo(packageInfo);

        //策略设置
        StrategyConfig strategyConfig = new StrategyConfig();
        strategyConfig.setInclude("tbl_user");  //设置当前参与生成的表名，参数为可变参数
        strategyConfig.setTablePrefix("tbl_");  //设置数据库表的前缀名称，模块名 = 数据库表名 - 前缀名  例如： User = tbl_user - tbl_
        strategyConfig.setRestControllerStyle(true);    //设置是否启用Rest风格
        strategyConfig.setVersionFieldName("version");  //设置乐观锁字段名
        strategyConfig.setLogicDeleteFieldName("deleted");  //设置逻辑删除字段名
        strategyConfig.setEntityLombokModel(true);  //设置是否启用lombok
        autoGenerator.setStrategy(strategyConfig);
        //2.执行生成操作
        autoGenerator.execute();
    }
}