一、MyBatis-Plus 简介
MyBatis-Plus(简称 MP)是 MyBatis 的增强工具,在保留 MyBatis 原生功能的基础上,提供了全自动化的 CRUD 操作、强大的分页插件、代码生成器等功能,显著减少开发工作量。与原生 MyBatis 相比,MyBatis-Plus 的核心优势在于:
无需编写 XML 文件:通过继承
BaseMapper
可直接使用通用 CRUD 方法。内置分页插件:简化分页查询逻辑。
注解式开发:通过注解配置实体类与数据库表的映射关系。
以下通过一个图书管理系统的代码示例,详解 MyBatis-Plus 的核心用法。
二、项目搭建与依赖引入
1. 添加依赖
在 pom.xml
中引入关键依赖:
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.ffyc.spring</groupId>
<artifactId>springboot-mybatisplus</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.13</version>
</parent>
<dependencies>
<!-- 引入web依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<!-- 引入mybatis-plus依赖 -->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.5.3.1</version>
</dependency>
<!-- <dependency>-->
<!-- <groupId>com.baomidou</groupId>-->
<!-- <artifactId>mybatis-plus-jsqlparser</artifactId>-->
<!-- <version>3.5.10.1</version>-->
<!-- </dependency>-->
<!-- 引入数据源Druid -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.2.18</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
2.整体结构
三、核心配置
1. 数据源与 Redis 配置
在 application-dev.yml
中配置数据库和 Redis:
spring:
datasource:
druid:
url: jdbc:mysql://localhost:3306/book_db?useSSL=false
username: root
password: 123456
redis:
host: localhost
port: 6379
2. 分页插件配置
通过 MybatisPlusLimitInterceptor
类启用分页功能:
@Configuration
@MapperScan("com.ffyc.springboot.mapper")
public class MybatisPlusLimitInterceptor {
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
return interceptor;
}
}
四、实体类与注解
1. 定义实体类
通过注解实现表字段映射:
package com.ffyc.springboot.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 java.io.Serializable;
@TableName("book_tab")//表名,与数据库对应
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Book implements Serializable { //设置序列化,为了使用Redis
@TableId(value = "book_id", type = IdType.AUTO)//主键,自增长
private Integer id;
@TableField("book_title")//字段映射
private String title;
@TableField("book_author")
private String author;
@TableField("book_price")
private Double price;
@TableField("book_desc")
private String description;
}
五、Mapper 层:继承 BaseMapper
1. 定义 Mapper 接口
继承 BaseMapper
后,可直接使用通用方法如 selectById()
、insert()
:
package com.ffyc.springboot.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.ffyc.springboot.entity.Book;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface IBookMapper extends BaseMapper<Book> {
//分页查询
Page<Book> selectByPage(Page<Book> page);
}
六、Service 层:实现 CRUD
1. 接口定义
package com.ffyc.springboot.service;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.ffyc.springboot.entity.Book;
import java.util.List;
public interface IBookService {
void addBook(Book book);
void deleteBook(int id);
void updateBook(Book book);
Page<Book> findAll(Page<Book> page);
}
2. 实现类
通过调用 BaseMapper
方法实现业务逻辑:
package com.ffyc.springboot.service.impl;
import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.ffyc.springboot.entity.Book;
import com.ffyc.springboot.mapper.IBookMapper;
import com.ffyc.springboot.service.IBookService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
@Slf4j
public class BookServiceImpl implements IBookService {
@Autowired
private IBookMapper bookMapper;
@Override
public void addBook(Book book) {
bookMapper.insert(book);
log.info("添加图书成功!");
}
@Override
public void deleteBook(int id) {
bookMapper.deleteById(id);
log.info("删除图书成功!");
}
@Override
public void updateBook(Book book) {
int update = bookMapper.update(book, new UpdateWrapper<Book>());
if (update > 0) {
log.info("更新图书成功!");
}else {
log.info("更新图书失败!");
}
}
@Override
@Cacheable(value = "book", key = "'bookList' + #page.current + '_' + #page.size")
public Page<Book> findAll(Page<Book> page) {
return bookMapper.selectByPage(page);
}
}
七、Controller 层:RESTful 接口
1. 分页查询示例
package com.ffyc.springboot.Controller;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.ffyc.springboot.entity.Book;
import com.ffyc.springboot.service.IBookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/api/book")
public class BookController {
@Autowired
private IBookService bookService;
@GetMapping("/findAll")
public Page<Book> findAll(@RequestParam(value = "page", defaultValue = "1") int current,
@RequestParam(value = "size", defaultValue = "10") int size){
Page<Book> page = new Page<>(current, size);
return bookService.findAll(page);
}
@GetMapping("/addBook")
public void addBook(Book book) {
bookService.addBook(book);
}
@PostMapping("/deleteBook")
public void deleteBook(Book book) {
bookService.deleteBook(book.getId());
}
@PostMapping("/updateBook")
public void updateBook(Book book) {
bookService.updateBook(book);
}
}
八、分页查询详解
1. 分页参数
current
:当前页码(默认 1)
size
:每页条数(默认 10)
2. 执行流程
前端请求:
GET /api/book/findAll?page=2&size=5
Controller 创建
Page
对象并传递给 Service。Service 调用 Mapper 的
selectByPage()
,MyBatis-Plus 自动拼接分页 SQL。
九、MyBatis vs MyBatis-Plus
十、总结
核心优势
-
高效开发:通过
BaseMapper
实现“开箱即用”的 CRUD。 -
灵活扩展:支持 Lambda 表达式、自定义 SQL。
-
企业级特性:分页、性能分析插件等。
通过本文的代码示例,可以看到 MyBatis-Plus 极大地简化了持久层开发。无论是分页查询还是缓存集成,均能以极少的代码实现复杂功能。建议在实际项目中结合代码生成器(如 MyBatis-Plus Generator
)进一步提升效率。
如果想进一步了解,可以前往官网查看学习文档https://baomidou.com/introduce/