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Lecture14-综合实战-员工管理模块

一、实战目标

把第 1～11 章的知识点串起来，做一个员工管理 RESTful 接口模块，包含：

数据库表使用最终形态（整合第 9、10 章的字段）：

CREATE TABLE t_emp (
    emp_id       INT PRIMARY KEY AUTO_INCREMENT COMMENT '员工ID',
    emp_no       VARCHAR(20)   NOT NULL COMMENT '员工编号',
    emp_name     VARCHAR(50)   NOT NULL COMMENT '员工姓名',
    emp_salary   DECIMAL(10,2) COMMENT '员工工资',
    emp_birthday DATE          COMMENT '出生日期',
    phone_num    VARCHAR(20)   COMMENT '手机号',
    dept_id      INT           COMMENT '部门ID',
    deleted      TINYINT       NOT NULL DEFAULT 0 COMMENT '逻辑删除：0未删 1已删',
    create_time  DATETIME      COMMENT '创建时间',
    update_time  DATETIME      COMMENT '更新时间',
    version      INT           NOT NULL DEFAULT 0 COMMENT '乐观锁版本号'
) COMMENT '员工表';

二、工程结构

module-mp-demo
├── pom.xml
└── src/main/java/com/atguigu/mp
    ├── ModuleMpApplication.java          # 主启动类
    ├── config/
    │   ├── MybatisPlusConfig.java        # 分页插件 + 乐观锁插件
    │   └── MyMetaObjectHandler.java      # 自动填充处理器
    ├── entity/
    │   └── Employee.java                 # 实体类
    ├── mapper/
    │   └── EmployeeMapper.java           # Mapper 接口
    ├── service/
    │   ├── EmployeeService.java          # Service 接口
    │   └── impl/
    │       └── EmployeeServiceImpl.java  # Service 实现
    └── controller/
        └── EmployeeController.java       # 控制器

三、各层完整代码

1、实体类 Employee

package com.atguigu.mp.entity;

import com.baomidou.mybatisplus.annotation.*;
import lombok.Data;

import java.math.BigDecimal;
import java.time.LocalDateTime;
import java.util.Date;

@Data
@TableName("t_emp")
public class Employee {

    @TableId(type = IdType.AUTO)
    private Integer empId;

    private String empNo;

    private String empName;

    private BigDecimal empSalary;

    private Date empBirthday;

    private String phoneNum;

    private Integer deptId;

    @TableLogic
    private Integer deleted;

    @TableField(fill = FieldFill.INSERT)
    private LocalDateTime createTime;

    @TableField(fill = FieldFill.INSERT_UPDATE)
    private LocalDateTime updateTime;

    @Version
    private Integer version;

}

2、Mapper 接口

package com.atguigu.mp.mapper;

import com.atguigu.mp.entity.Employee;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface EmployeeMapper extends BaseMapper<Employee> {
}

3、Service 接口与实现

package com.atguigu.mp.service;

import com.atguigu.mp.entity.Employee;
import com.baomidou.mybatisplus.extension.service.IService;

public interface EmployeeService extends IService<Employee> {
}

package com.atguigu.mp.service.impl;

import com.atguigu.mp.entity.Employee;
import com.atguigu.mp.mapper.EmployeeMapper;
import com.atguigu.mp.service.EmployeeService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;

@Service
public class EmployeeServiceImpl extends ServiceImpl<EmployeeMapper, Employee> implements EmployeeService {
}

4、配置类

package com.atguigu.mp.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.OptimisticLockerInnerInterceptor;
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();
        // 分页插件
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        // 乐观锁插件
        interceptor.addInnerInterceptor(new OptimisticLockerInnerInterceptor());
        return interceptor;
    }

}

package com.atguigu.mp.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());
    }

}

5、控制器 EmployeeController

package com.atguigu.mp.controller;

import com.atguigu.mp.entity.Employee;
import com.atguigu.mp.service.EmployeeService;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
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.web.bind.annotation.*;

import java.math.BigDecimal;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/emp")
public class EmployeeController {

    @Autowired
    private EmployeeService employeeService;

    // ===== 1. 分页 + 多条件查询：GET /emp/page?pageNum=1&pageSize=3&name=张&deptId=1&minSalary=5000 =====
    @GetMapping("/page")
    public Page<Employee> page(@RequestParam(defaultValue = "1") Integer pageNum,
                               @RequestParam(defaultValue = "3") Integer pageSize,
                               @RequestParam(required = false) String name,
                               @RequestParam(required = false) Integer deptId,
                               @RequestParam(required = false) BigDecimal minSalary,
                               @RequestParam(required = false) BigDecimal maxSalary) {
        Page<Employee> page = new Page<>(pageNum, pageSize);

        // 条件可选：值为 null 时自动忽略
        LambdaQueryWrapper<Employee> wrapper = new LambdaQueryWrapper<>();
        wrapper.like(name != null, Employee::getEmpName, name)
               .eq(deptId != null, Employee::getDeptId, deptId)
               .ge(minSalary != null, Employee::getEmpSalary, minSalary)
               .le(maxSalary != null, Employee::getEmpSalary, maxSalary)
               .orderByDesc(Employee::getEmpSalary);

        return employeeService.page(page, wrapper);
    }

    // ===== 2. 按主键查询：GET /emp/1 =====
    @GetMapping("/{id}")
    public Employee getById(@PathVariable Integer id) {
        return employeeService.getById(id);
    }

    // ===== 3. 新增员工：POST /emp（请求体 JSON）=====
    @PostMapping
    public boolean save(@RequestBody Employee employee) {
        // create_time / update_time 自动填充；主键自增回填
        return employeeService.save(employee);
    }

    // ===== 4. 修改员工：PUT /emp（请求体 JSON，携带 version）=====
    @PutMapping
    public boolean update(@RequestBody Employee employee) {
        // 乐观锁生效：前端必须回传 version，version 对不上则更新失败
        boolean updated = employeeService.updateById(employee);
        if (!updated) {
            throw new RuntimeException("数据已被他人修改，请刷新后重试");
        }
        return true;
    }

    // ===== 5. 删除员工：DELETE /emp/1（逻辑删除）=====
    @DeleteMapping("/{id}")
    public boolean delete(@PathVariable Integer id) {
        return employeeService.removeById(id);   // 实际执行 UPDATE deleted=1
    }

    // ===== 6. 按部门统计人数：GET /emp/count/byDept =====
    @GetMapping("/count/byDept")
    public List<Map<String, Object>> countByDept() {
        // 统计类查询：查询列不是实体属性，用 QueryWrapper + selectMaps
        QueryWrapper<Employee> wrapper = new QueryWrapper<>();
        wrapper.select("dept_id", "count(*) as empCount")
               .groupBy("dept_id");
        return employeeService.listMaps(wrapper);
    }

}

四、测试

工程中加入 spring-boot-starter-web 依赖后，启动主启动类，用浏览器 / Postman / IDEA HTTP Client 测试：

小提示：修改接口必须回传 version，否则乐观锁条件不满足更新失败——这正是乐观锁设计的体现。

五、全教程知识地图

六、常见问题速查（全教程汇总）

七、结语

到这里，MyBatis-Plus 的常用操作就学完了。回顾核心心法：

单表操作不写 SQL：继承 BaseMapper / IService，方法开箱即用； 动态条件用 Wrapper：LambdaQueryWrapper + 可选条件，一个方法吃遍各种查询； 通用能力靠插件：分页、乐观锁、逻辑删除、自动填充，配一次全表生效。

把这些能力组合起来，一个模块的增删改查接口几十分钟就能写完。后续学 Spring Boot、Spring Cloud 时，这套数据访问方式会一直伴随你。