SpringBoot整合MybatisPlus

目錄（可點選直接跳轉，但還是建議按照順序觀看，四部分具有一定的關聯性）：

實現基礎的增刪改查

實現自動填充功能

實現邏輯刪除

實現分頁

首先給出四部分完整的專案結構

一、實現基礎的增刪改查功能

1.建立專案、選擇依賴

選擇Spring Web、JDBC API、MyBatis Framework、MySQL Driver

2.在pom檔案中引入相關依賴

<dependency>

    <groupId>mysql</groupId>

    <artifactId>mysql-connector-java</artifactId>

    <!-- 修改jdbc版本 -->

    <version>5.1.47</version>

    <scope>runtime</scope>

</dependency>

<!-- 引入MybatisPlus的啟動器 -->

<dependency>

    <groupId>com.baomidou</groupId>

    <artifactId>mybatis-plus-boot-starter</artifactId>

    <version>3.3.2</version>

</dependency>

<!-- 引入lombok -->

<dependency>

    <groupId>org.projectlombok</groupId>

    <artifactId>lombok</artifactId>

</dependency>

<!-- 引入druid連線池 -->

<dependency>

    <groupId>com.alibaba</groupId>

    <artifactId>druid</artifactId>

    <version>1.2.6</version>

</dependency>

<!-- 引入log4j -->

<dependency>

    <groupId>log4j</groupId>

    <artifactId>log4j</artifactId>

    <version>1.2.17</version>

</dependency>

3.建庫、建表、插入資料

CREATE DATABASE db_mybatisplus;

USE db_mybatisplus;

CREATE TABLE tab_teacher(

    pk_teacher_id INT PRIMARY KEY AUTO_INCREMENT COMMENT '老師主鍵id,起始為1',

    teacher_name VARCHAR(10) COMMENT '老師姓名',

    teacher_sex CHAR(1) COMMENT '老師性別',

    teacher_salary DOUBLE(6,1) COMMENT '老師工資'

);

-- 反覆執行多次，隨機插入多條資料

INSERT INTO tab_teacher VALUES(

    NULL,

    SUBSTR(MD5(RAND()), 1, 5),

    IF(RAND()>0.5, '男', '女'),

    RAND()*10000+1000

);

SELECT * FROM tab_teacher;

4.配置核心配置檔案

# 配置連線資料庫的四大引數

spring.datasource.driver-class-name=com.mysql.jdbc.Driver

spring.datasource.url=jdbc:mysql://192.168.133.139/db_mybatisplus?useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true

spring.datasource.username=root

spring.datasource.password=root

# 指定連線池的型別

spring.datasource.type=com.alibaba.druid.pool.DruidDataSource

# 顯示SQL語句

mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

5.建立實體類

package cn.byuan.entity;

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.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

import lombok.experimental.Accessors;

import java.io.Serializable;

@NoArgsConstructor// 建立無參的構造方法

@AllArgsConstructor// 建立滿參的構造方法

@Accessors(chain = true)// 使用鏈式方法

@Data// 重寫toString方法等方法

@TableName("tab_teacher")// 對應表名

public class Teacher implements Serializable {

    @TableId(value = "pk_teacher_id", type = IdType.AUTO)// 主鍵必須有TableId註解

    private Integer teacherId;

    @TableField("teacher_name")

    private String teacherName;

    @TableField("teacher_sex")

    private String teacherSex;

    @TableField("teacher_salary")

    private Double teacherSalary;

}

6.建立Teacher類的dao介面，繼承BaseMapper介面，使用BaseMapper介面的方法

這裡我省去了mapper層，直接讓dao層介面繼承BaseMapper

這裡要牢記一個原則：在啟動類對繼承BaseMapper的類進行掃描，誰繼承BaseMapper類就對它進行掃描

package cn.byuan.dao;

import cn.byuan.entity.Teacher;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;

import org.springframework.stereotype.Repository;

@Repository

public interface TeacherDao extends BaseMapper<Teacher> {

}

7.建立service介面及實現類

介面：

import cn.byuan.entity.Teacher;

import java.util.List;

public interface TeacherService {

//    新增一位老師

    Integer addOneTeacher(Teacher teacher);

//    根據id刪除一位老師

    Integer deleteOneTeacherByTeacherId(Integer teacherId);

//    修改一位老師的資訊

    Integer updateOneTeacher(Teacher teacher);

//    根據id查詢一位老師

    Teacher getOneTeacherByTeacherId(Integer teacherId);

//    獲取所有老師

    List<Teacher> getAllTeacher();

}

實現類：

package cn.byuan.service;

import cn.byuan.dao.TeacherDao;

import cn.byuan.entity.Teacher;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import java.util.List;

@Service

public class TeacherServiceImp implements TeacherService{

    @Autowired

    private TeacherDao teacherDao;

    //    新增一位老師

    public Integer addOneTeacher(Teacher teacher){

        return teacherDao.insert(teacher);

    }

    //    根據id刪除一位老師

    public Integer deleteOneTeacherByTeacherId(Integer teacherId){

        return teacherDao.deleteById(teacherId);

    }

    //    修改一位老師的資訊

    public Integer updateOneTeacher(Teacher teacher){

        return teacherDao.updateById(teacher);

    }

    //    根據id查詢一位老師

    public Teacher getOneTeacherByTeacherId(Integer teacherId){

        return teacherDao.selectById(teacherId);

    }

    //    獲取所有老師

    public List<Teacher> getAllTeacher(){

        return teacherDao.selectList(null);

    }

}

8.在啟動類對繼承BaseMapper的類配置掃描

誰繼承了BaseMapper就對誰進行掃描，因為之前我省去了mapper層，直接讓dao層介面繼承BaseMapper，因此這裡掃描的是dao包

package cn.byuan;

import org.mybatis.spring.annotation.MapperScan;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

@MapperScan("cn.byuan.dao")// 那一層繼承了BaseMapper就對那一層進行掃描

public class Test005SpringbootMybatisplusApplication {

    public static void main(String[] args) {

        SpringApplication.run(Test005SpringbootMybatisplusApplication.class, args);

    }

}

9.在測試類進行測試

package cn.byuan;

import cn.byuan.entity.Teacher;

import cn.byuan.service.TeacherService;

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest

class TeacherDaoOneTests {

    @Autowired

    private TeacherService teacherService;

    @Test

    void addOneTeacherTest(){

        Teacher teacher = new Teacher()

                .setTeacherName("test2")

                .setTeacherSex("女")

                .setTeacherSalary(9876.5);

        teacherService.addOneTeacher(teacher);

    }

    @Test

    void deleteOneTeacherByTeacherIdTest(){

        teacherService.deleteOneTeacherByTeacherId(2);

    }

    @Test

    void updateOneTeacher(){

        Teacher teacher = new Teacher()

                .setTeacherId(1)

                .setTeacherName("qwe12")

                .setTeacherSex("女")

                .setTeacherSalary(1234.5);

        teacherService.updateOneTeacher(teacher);

    }

    @Test

    void getOneTeacherByTeacherId(){

        teacherService.getOneTeacherByTeacherId(1);

    }

    @Test

    void getAllTeacher(){

        teacherService.getAllTeacher();

    }

}

測試結果：

二、實現自動填充功能

自動填充功能一般可以用作記錄操作發生時間，如某列的最後修改時間等，本部分程式碼基於第一部分：實現基礎的增刪改查、

1.修改資料庫中的表結構

-- 修改資料庫中表結構

ALTER TABLE tab_teacher ADD create_time TIMESTAMP COMMENT '記錄插入時間';

ALTER TABLE tab_teacher ADD update_time TIMESTAMP COMMENT '記錄修改時間';

-- 更新所有表中資料

UPDATE tab_teacher SET create_time=NOW();

UPDATE tab_teacher SET update_time=NOW();

SELECT * FROM tab_teacher;

2.修改實體類

這一步簡單來說就是將增加的兩列新增進Teacher類的屬性中，其餘與第一部分保持一致；

為實現自動填充還應在新加入的兩個屬性的TableField中增加"fill"屬性

package cn.byuan.entity;

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.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

import lombok.experimental.Accessors;

import java.io.Serializable;

import java.util.Date;

@NoArgsConstructor// 建立無參的構造方法

@AllArgsConstructor// 建立滿參的構造方法

@Accessors(chain = true)// 使用鏈式方法

@Data// 重寫toString方法等方法

@TableName("tab_teacher")// 對應表名

public class Teacher implements Serializable {

    @TableId(value = "pk_teacher_id", type = IdType.AUTO)// 主鍵必須有TableId註解

    private Integer teacherId;

    @TableField("teacher_name")

    private String teacherName;

    @TableField("teacher_sex")

    private String teacherSex;

    @TableField("teacher_salary")

    private Double teacherSalary;

//    增加的兩列屬性

    @TableField(value = "create_time", fill = FieldFill.INSERT)// 插入時自動填充

    private Date createTime;

    @TableField(value = "update_time", fill = FieldFill.INSERT_UPDATE)// 插入和修改時自動填充

    private Date updateTime;

}

3.建立handler層，實現MetaObjectHandler介面，重寫insertFill與updateFill方法，指定填充的欄位及屬性值

package cn.byuan.handler;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;

import org.apache.ibatis.reflection.MetaObject;

import org.springframework.stereotype.Component;

import java.util.Date;

@Component

public class TeacherHandler implements MetaObjectHandler {

    @Override

    public void insertFill(MetaObject metaObject) {

        this.strictInsertFill(metaObject, "createTime", Date.class, new Date());

        this.strictInsertFill(metaObject, "updateTime", Date.class, new Date());

    }

    @Override

    public void updateFill(MetaObject metaObject) {

        this.strictUpdateFill(metaObject, "updateTime", Date.class, new Date());

    }

}

4.進行測試

這裡我們只測試增加和修改兩個方法

package cn.byuan;

import cn.byuan.entity.Teacher;

import cn.byuan.service.TeacherService;

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest

class TeacherDaoTwoTests {

    @Autowired

    private TeacherService teacherService;

    @Test

    void addOneTeacherTest(){

        Teacher teacher = new Teacher()

                .setTeacherName("test2")

                .setTeacherSex("女")

                .setTeacherSalary(9876.5);

        teacherService.addOneTeacher(teacher);

    }

    @Test

    void updateOneTeacher(){

        Teacher teacher = new Teacher()

                .setTeacherId(1)

                .setTeacherName("wer23")

                .setTeacherSex("女")

                .setTeacherSalary(1234.5);

        teacherService.updateOneTeacher(teacher);

    }

}

從SQL語句可以看出，在執行update方法時，已自動為我們填充欄位

資料庫中新插入資料也沒有問題

三、實現邏輯刪除功能

資料是無價的，因此一般而言我們不會直接刪除資料。對於"刪除"我們一般的做法是定義一個欄位來記錄本行資料的可見性

1.修改資料庫中的表結構

新增一個欄位作為標記

-- 修改資料庫中表結構, 新增一個欄位作為標記

ALTER TABLE tab_teacher ADD visibility TINYINT COMMENT "0表示未刪除，1表示刪除";

-- 更新表中所有資料, 全部設定為未刪除

UPDATE tab_teacher SET visibility=0;

2.在實體類中新增欄位，並新增TableField和TableLogic兩個註解

package cn.byuan.entity;

import com.baomidou.mybatisplus.annotation.*;

import lombok.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

import lombok.experimental.Accessors;

import java.io.Serializable;

import java.util.Date;

@NoArgsConstructor// 建立無參的構造方法

@AllArgsConstructor// 建立滿參的構造方法

@Accessors(chain = true)// 使用鏈式方法

@Data// 重寫toString方法等方法

@TableName("tab_teacher")// 對應表名

public class Teacher implements Serializable {

    @TableId(value = "pk_teacher_id", type = IdType.AUTO)// 主鍵必須有TableId註解

    private Integer teacherId;

    @TableField("teacher_name")

    private String teacherName;

    @TableField("teacher_sex")

    private String teacherSex;

    @TableField("teacher_salary")

    private Double teacherSalary;

    @TableField(value = "create_time", fill = FieldFill.INSERT)// 插入時自動填充

    private Date createTime;

    @TableField(value = "update_time", fill = FieldFill.INSERT_UPDATE)// 插入和修改時自動填充

    private Date updateTime;

//    新新增進來的欄位

    @TableField(value = "visibility", fill = FieldFill.INSERT)

    @TableLogic(value = "0", delval = "1")// 指定次欄位為邏輯刪除欄位, 預設0是未刪除, 1是已刪除

    private Integer visibility;

}

3.在TeacherHandler中指定visibility欄位的初始值

package cn.byuan.handler;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;

import org.apache.ibatis.reflection.MetaObject;

import org.springframework.stereotype.Component;

import java.util.Date;

@Component

public class TeacherHandler implements MetaObjectHandler {

    @Override

    public void insertFill(MetaObject metaObject) {

        this.strictInsertFill(metaObject, "createTime", Date.class, new Date());

        this.strictInsertFill(metaObject, "updateTime", Date.class, new Date());

//        新新增的欄位

        this.strictInsertFill(metaObject, "visibility", Integer.class, 0);

    }

    @Override

    public void updateFill(MetaObject metaObject) {

        this.strictUpdateFill(metaObject, "updateTime", Date.class, new Date());

    }

}

4.進行測試

這裡只測試兩個方法，一個是刪除指定id值的老師，一個是根據被刪除的老師id查詢該老師是否可以被查詢

package cn.byuan;

import cn.byuan.entity.Teacher;

import cn.byuan.service.TeacherService;

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest

class TeacherDaoThreeTests {

    @Autowired

    private TeacherService teacherService;

    @Test

    void deleteOneTeacherByTeacherIdTest(){

//        刪除id為1的老師

        teacherService.deleteOneTeacherByTeacherId(1);

    }

    @Test

    void getOneTeacherByTeacherId(){

//        查詢id為1的老師

        teacherService.getOneTeacherByTeacherId(1);

    }

}

可以看到，當我們執行delete方法時，實際上執行的是update方法

而查詢語句並沒有查詢到該老師

資料庫中id為1的老師資訊依然存在

四、實現分頁功能

1.建立一個配置類，通過方法返回一個PaginationInterceptor

package cn.byuan.conf;

import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;

import org.mybatis.spring.annotation.MapperScan;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

@Configuration

@MapperScan("cn.byuan.dao")

public class PageConfig {

    @Bean

    public PaginationInterceptor PaginationInterceptor(){

        return new PaginationInterceptor();

    }

}

2.在service中根據selectPage方法進行分頁

這裡展示兩種分頁方式，對錶中所有資料進行分頁以及根據條件進行分頁

介面：

package cn.byuan.service;

import cn.byuan.entity.Teacher;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

import java.util.List;

public interface TeacherService {

//    新增一位老師

    Integer addOneTeacher(Teacher teacher);

//    根據id刪除一位老師

    Integer deleteOneTeacherByTeacherId(Integer teacherId);

//    修改一位老師的資訊

    Integer updateOneTeacher(Teacher teacher);

//    根據id查詢一位老師

    Teacher getOneTeacherByTeacherId(Integer teacherId);

//    獲取所有老師

    List<Teacher> getAllTeacher();

//    該部分增加的方法

//    對錶中所有資訊進行分頁, 傳入引數為要查詢的頁數

    Page<Teacher> getAllTeacherPage(Integer pageNumber);

//    按條件(性別)進行分頁

    Page<Teacher> getAllTeacherByTeacherSexPage(Integer pageNumber, String teacherSex);

}

實現類：

package cn.byuan.service;

import cn.byuan.dao.TeacherDao;

import cn.byuan.entity.Teacher;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import java.util.List;

@Service

public class TeacherServiceImp implements TeacherService{

    @Autowired

    private TeacherDao teacherDao;

    //    新增一位老師

    public Integer addOneTeacher(Teacher teacher){

        return teacherDao.insert(teacher);

    }

    //    根據id刪除一位老師

    public Integer deleteOneTeacherByTeacherId(Integer teacherId){

        return teacherDao.deleteById(teacherId);

    }

    //    修改一位老師的資訊

    public Integer updateOneTeacher(Teacher teacher){

        return teacherDao.updateById(teacher);

    }

    //    根據id查詢一位老師

    public Teacher getOneTeacherByTeacherId(Integer teacherId){

        return teacherDao.selectById(teacherId);

    }

    //    獲取所有老師

    public List<Teacher> getAllTeacher(){

        return teacherDao.selectList(null);

    }

    //    該部分增加的方法

    //    對錶中所有資訊進行分頁, 傳入引數為要查詢的頁數

    public Page<Teacher> getAllTeacherPage(Integer pageNumber){

        QueryWrapper<Teacher> teacherQueryWrapper = new QueryWrapper<>();

        Page<Teacher> teacherPage = new Page<>(pageNumber, 5);// 每頁大小為5

        teacherDao.selectPage(teacherPage, teacherQueryWrapper);

        return teacherPage;

    }

    //    按條件(性別)進行分頁

    public Page<Teacher> getAllTeacherByTeacherSexPage(Integer pageNumber, String teacherSex){

        QueryWrapper<Teacher> teacherQueryWrapper = new QueryWrapper<>();

        teacherQueryWrapper.eq("teacher_sex", teacherSex);// 根據條件進行分頁, 這裡填寫的是表中的列名

        Page<Teacher> teacherPage = new Page<>(pageNumber, 5);

        teacherDao.selectPage(teacherPage, teacherQueryWrapper);

        return teacherPage;

    }

}

3.進行測試

package cn.byuan;

import cn.byuan.entity.Teacher;

import cn.byuan.service.TeacherService;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest

class TeacherDaoFourTests {

    @Autowired

    private TeacherService teacherService;

    @Test

    void getAllTeacherPageTest(){

        //    檢視第三頁

        Page<Teacher> teacherPage = teacherService.getAllTeacherPage(3);

        teacherPage.getRecords().forEach(System.out::println);

    }

    @Test

    void getAllTeacherByTeacherSexPageTest(){

        //    查詢男生第1頁的內容

        Page<Teacher> teacherPage = teacherService.getAllTeacherByTeacherSexPage(1, "男");

        teacherPage.getRecords().forEach(System.out::println);

    }

}

測試結果

附：Page物件的一些常用方法

Page<Object> page = new Page<>(1, 6);// 指定當前頁, 每頁記錄數

page.getCurrent();// 獲取當前頁

page.getTotal();// 獲取總記錄數

page.getSize();// 獲取每頁的記錄數

page.getRecords();// 獲取當前頁資料的集合

page.getPages();// 獲取總頁數

page.hasNext();// 是否存在下一頁

page.hasPrevious();// 是否存在上一頁

原始碼地址：https://github.com/byuan98/springboot-integration/tree/master/test005_springboot_mybatisplus