本文目录导读：
我来为你提供一个完整的MyBatis-Plus入门案例，从环境搭建到基本CRUD操作。
环境准备
1 创建Spring Boot项目
在pom.xml中添加依赖：
<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.0</version>
<relativePath/>
</parent>
<groupId>com.example</groupId>
<artifactId>mybatis-plus-demo</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<!-- Spring Boot Web -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- MySQL驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!-- MyBatis-Plus -->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter</artifactId>
<version>3.5.2</version>
</dependency>
<!-- Lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<!-- 测试 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
2 配置文件 application.yml
server:
port: 8080
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/mybatis_plus_demo?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
username: root
password: 123456
# MyBatis-Plus配置
mybatis-plus:
# 实体扫描，多个package用逗号或者分号分隔
type-aliases-package: com.example.entity
# 控制台打印SQL日志
configuration:
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
map-underscore-to-camel-case: true
# 全局配置
global-config:
db-config:
# 主键类型
id-type: auto
# 表名前缀
# table-prefix: t_
# 逻辑删除字段
logic-delete-field: deleted
logic-delete-value: 1
logic-not-delete-value: 0
3 数据库表结构
-- 创建数据库
CREATE DATABASE IF NOT EXISTS mybatis_plus_demo
DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;
USE mybatis_plus_demo;
-- 用户表
DROP TABLE IF EXISTS user;
CREATE TABLE user (
id BIGINT(20) PRIMARY KEY AUTO_INCREMENT COMMENT '主键ID',
name VARCHAR(30) NOT NULL COMMENT '姓名',
age INT(11) DEFAULT NULL COMMENT '年龄',
email VARCHAR(50) DEFAULT NULL COMMENT '邮箱',
create_time DATETIME DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
update_time DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
deleted INT(1) DEFAULT 0 COMMENT '逻辑删除标记'
) COMMENT '用户表';
-- 插入测试数据
INSERT INTO user (name, age, email) VALUES
('张三', 25, 'zhangsan@example.com'),
('李四', 30, 'lisi@example.com'),
('王五', 28, 'wangwu@example.com'),
('赵六', 22, 'zhaoliu@example.com');
创建实体类
package com.example.entity;
import com.baomidou.mybatisplus.annotation.*;
import lombok.Data;
import java.time.LocalDateTime;
@Data
@TableName("user")
public class User {
@TableId(type = IdType.AUTO)
private Long id;
private String name;
private Integer age;
private String email;
@TableField(fill = FieldFill.INSERT)
private LocalDateTime createTime;
@TableField(fill = FieldFill.INSERT_UPDATE)
private LocalDateTime updateTime;
@TableLogic
@TableField(select = false)
private Integer deleted;
}
创建Mapper接口
package com.example.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.entity.User;
import org.apache.ibatis.annotations.Mapper;
@Mapper
public interface UserMapper extends BaseMapper<User> {
// 可以自定义方法
}
创建Service层
package com.example.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.example.entity.User;
public interface UserService extends IService<User> {
// 业务方法
}
package com.example.service.impl;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.entity.User;
import com.example.mapper.UserMapper;
import com.example.service.UserService;
import org.springframework.stereotype.Service;
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements UserService {
// 实现业务方法
}
创建Controller
package com.example.controller;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.entity.User;
import com.example.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
/**
* 查询所有用户
*/
@GetMapping("/list")
public List<User> list() {
return userService.list();
}
/**
* 根据ID查询用户
*/
@GetMapping("/{id}")
public User getUserById(@PathVariable Long id) {
return userService.getById(id);
}
/**
* 新增用户
*/
@PostMapping("/add")
public User addUser(@RequestBody User user) {
userService.save(user);
return user;
}
/**
* 更新用户
*/
@PutMapping("/{id}")
public User updateUser(@PathVariable Long id, @RequestBody User user) {
user.setId(id);
userService.updateById(user);
return user;
}
/**
* 删除用户（逻辑删除）
*/
@DeleteMapping("/{id}")
public String deleteUser(@PathVariable Long id) {
boolean success = userService.removeById(id);
return success ? "删除成功" : "删除失败";
}
/**
* 条件查询 - 通过名字查询
*/
@GetMapping("/search")
public List<User> searchUser(@RequestParam(required = false) String name,
@RequestParam(required = false) Integer age) {
QueryWrapper<User> wrapper = new QueryWrapper<>();
if (name != null && !name.isEmpty()) {
wrapper.like("name", name);
}
if (age != null) {
wrapper.eq("age", age);
}
wrapper.orderByDesc("age");
return userService.list(wrapper);
}
/**
* 分页查询
*/
@GetMapping("/page")
public IPage<User> pageQuery(@RequestParam(defaultValue = "1") Integer current,
@RequestParam(defaultValue = "10") Integer size) {
Page<User> page = new Page<>(current, size);
userService.page(page);
return page;
}
/**
* 批量删除
*/
@DeleteMapping("/batch")
public String batchDelete(@RequestBody List<Long> ids) {
boolean success = userService.removeByIds(ids);
return success ? "批量删除成功" : "批量删除失败";
}
/**
* 使用条件构造器精确更新
*/
@PutMapping("/update-by-condition")
public String updateByCondition(@RequestParam Long id, @RequestParam Integer age) {
UpdateWrapper<User> updateWrapper = new UpdateWrapper<>();
updateWrapper.eq("id", id)
.set("age", age);
boolean success = userService.update(updateWrapper);
return success ? "更新成功" : "更新失败";
}
}
创建配置类（可选）
1 分页插件配置
package com.example.config;
import com.baomidou.mybatisplus.annotation.DbType;
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 MybatisPlusConfig {
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
// 添加分页插件
interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
return interceptor;
}
}
2 字段自动填充配置（可选）
package com.example.config;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.time.LocalDateTime;
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
@Override
public void insertFill(MetaObject metaObject) {
this.strictInsertFill(metaObject, "createTime", LocalDateTime.class, LocalDateTime.now());
this.strictInsertFill(metaObject, "updateTime", LocalDateTime.class, LocalDateTime.now());
}
@Override
public void updateFill(MetaObject metaObject) {
this.strictUpdateFill(metaObject, "updateTime", LocalDateTime.class, LocalDateTime.now());
}
}
启动类
package com.example;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan("com.example.mapper")
public class MybatisPlusDemoApplication {
public static void main(String[] args) {
SpringApplication.run(MybatisPlusDemoApplication.class, args);
}
}
测试代码
package com.example;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.example.entity.User;
import com.example.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@SpringBootTest
class MybatisPlusDemoApplicationTests {
@Autowired
private UserMapper userMapper;
/**
* 测试插入
*/
@Test
void testInsert() {
User user = new User();
user.setName("测试用户");
user.setAge(20);
user.setEmail("test@example.com");
int result = userMapper.insert(user);
System.out.println("插入结果：" + result);
System.out.println("生成ID：" + user.getId());
}
/**
* 测试查询
*/
@Test
void testSelect() {
// 根据ID查询
User user = userMapper.selectById(1L);
System.out.println("根据ID查询：" + user);
// 查询所有
List<User> userList = userMapper.selectList(null);
System.out.println("查询所有：" + userList);
// 条件查询
QueryWrapper<User> wrapper = new QueryWrapper<>();
wrapper.eq("age", 25);
List<User> ageList = userMapper.selectList(wrapper);
System.out.println("条件查询：" + ageList);
}
/**
* 测试更新
*/
@Test
void testUpdate() {
User user = new User();
user.setId(1L);
user.setAge(26);
int result = userMapper.updateById(user);
System.out.println("更新结果：" + result);
}
/**
* 测试删除
*/
@Test
void testDelete() {
// 根据ID删除（逻辑删除）
int result = userMapper.deleteById(1L);
System.out.println("删除结果：" + result);
// 根据条件删除
Map<String, Object> map = new HashMap<>();
map.put("name", "测试用户");
int result2 = userMapper.deleteByMap(map);
System.out.println("条件删除结果：" + result2);
}
}
常用功能总结
1 QueryWrapper常用方法
// 创建查询条件
QueryWrapper<User> wrapper = new QueryWrapper<>();
// 等于
wrapper.eq("name", "张三");
// 不等于
wrapper.ne("age", 25);
// 大于
wrapper.gt("age", 20);
// 小于
wrapper.lt("age", 30);
// 大于等于
wrapper.ge("age", 25);
// 小于等于
wrapper.le("age", 25);
// LIKE查询
wrapper.like("name", "张");
// IN查询
wrapper.in("id", Arrays.asList(1, 2, 3));
// BETWEEN
wrapper.between("age", 20, 30);
// 排序
wrapper.orderByAsc("age");
wrapper.orderByDesc("create_time");
// 限制数量
wrapper.last("LIMIT 10");
2 常用注解
@TableName("user") // 指定表名
@TableId(type = IdType.AUTO) // 主键策略
@TableField("name") // 指定字段名
@TableField(exist = false) // 非数据库字段
@TableField(fill = FieldFill.INSERT) // 自动填充
@TableLogic // 逻辑删除
@Version // 乐观锁
这个入门案例涵盖了MyBatis-Plus的主要功能，包括基本的CRUD操作、条件构造器、分页查询、逻辑删除等特性，你可以根据实际需求进行扩展和调整。
