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【JavaWeb学习Day16】

2025/7/3 13:14:49 来源:https://blog.csdn.net/weixin_74799820/article/details/145670705  浏览:    关键词:【JavaWeb学习Day16】

Tlias智能学习系统

员工管理:

员工列表查询(Tlias)

需求:查询所有员工信息,并查询出部门名称。(涉及到的表:emp、dept)

准备工作:

1.准备数据库表emp、emp_expr。

-- 员工表
create table emp(id int unsigned primary key auto_increment comment 'ID,主键',username varchar(20) not null unique comment '用户名',password varchar(50) default '123456' comment '密码',name varchar(10) not null comment '姓名',gender tinyint unsigned not null comment '性别, 1:男, 2:女',phone char(11) not null unique comment '手机号',job tinyint unsigned comment '职位, 1 班主任, 2 讲师 , 3 学工主管, 4 教研主管, 5 咨询师',salary int unsigned comment '薪资',image varchar(300) comment '头像',entry_date date comment '入职日期',dept_id int unsigned comment '部门ID',create_time datetime comment '创建时间',update_time datetime comment '修改时间'
) comment '员工表';
​
​
INSERT INTO emp VALUES (1,'shinaian','123456','施耐庵',1,'13309090001',4,15000,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2000-01-01',2,'2023-10-20 16:35:33','2023-11-16 16:11:26'),(2,'songjiang','123456','宋江',1,'13309090002',2,8600,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2015-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:35:37'),(3,'lujunyi','123456','卢俊义',1,'13309090003',2,8900,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2008-05-01',2,'2023-10-20 16:35:33','2023-10-20 16:35:39'),(4,'wuyong','123456','吴用',1,'13309090004',2,9200,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2007-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:35:41'),(5,'gongsunsheng','123456','公孙胜',1,'13309090005',2,9500,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2012-12-05',2,'2023-10-20 16:35:33','2023-10-20 16:35:43'),(6,'huosanniang','123456','扈三娘',2,'13309090006',3,6500,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2013-09-05',1,'2023-10-20 16:35:33','2023-10-20 16:35:45'),(7,'chaijin','123456','柴进',1,'13309090007',1,4700,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2005-08-01',1,'2023-10-20 16:35:33','2023-10-20 16:35:47'),(8,'likui','123456','李逵',1,'13309090008',1,4800,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2014-11-09',1,'2023-10-20 16:35:33','2023-10-20 16:35:49'),(9,'wusong','123456','武松',1,'13309090009',1,4900,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2011-03-11',1,'2023-10-20 16:35:33','2023-10-20 16:35:51'),(10,'linchong','123456','林冲',1,'13309090010',1,5000,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2013-09-05',1,'2023-10-20 16:35:33','2023-10-20 16:35:53'),(11,'huyanzhuo','123456','呼延灼',1,'13309090011',2,9700,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2007-02-01',2,'2023-10-20 16:35:33','2023-10-20 16:35:55'),(12,'xiaoliguang','123456','小李广',1,'13309090012',2,10000,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2008-08-18',2,'2023-10-20 16:35:33','2023-10-20 16:35:57'),(13,'yangzhi','123456','杨志',1,'13309090013',1,5300,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2012-11-01',1,'2023-10-20 16:35:33','2023-10-20 16:35:59'),(14,'shijin','123456','史进',1,'13309090014',2,10600,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2002-08-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:01'),(15,'sunerniang','123456','孙二娘',2,'13309090015',2,10900,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2011-05-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:03'),(16,'luzhishen','123456','鲁智深',1,'13309090016',2,9600,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2010-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:05'),(17,'liying','12345678','李应',1,'13309090017',1,5800,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2015-03-21',1,'2023-10-20 16:35:33','2023-10-20 16:36:07'),(18,'shiqian','123456','时迁',1,'13309090018',2,10200,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2015-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:09'),(19,'gudasao','123456','顾大嫂',2,'13309090019',2,10500,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2008-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:11'),(20,'ruanxiaoer','123456','阮小二',1,'13309090020',2,10800,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2018-01-01',2,'2023-10-20 16:35:33','2023-10-20 16:36:13'),(21,'ruanxiaowu','123456','阮小五',1,'13309090021',5,5200,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2015-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:15'),(22,'ruanxiaoqi','123456','阮小七',1,'13309090022',5,5500,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2016-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:17'),(23,'ruanji','123456','阮籍',1,'13309090023',5,5800,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2012-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:19'),(24,'tongwei','123456','童威',1,'13309090024',5,5000,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2006-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:21'),(25,'tongmeng','123456','童猛',1,'13309090025',5,4800,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2002-01-01',3,'2023-10-20 16:35:33','2023-10-20 16:36:23'),(26,'yanshun','123456','燕顺',1,'13309090026',5,5400,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2011-01-01',3,'2023-10-20 16:35:33','2023-11-08 22:12:46'),(27,'lijun','123456','李俊',1,'13309090027',2,6600,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2004-01-01',2,'2023-10-20 16:35:33','2023-11-16 17:56:59'),(28,'lizhong','123456','李忠',1,'13309090028',5,5000,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2007-01-01',3,'2023-10-20 16:35:33','2023-11-17 16:34:22'),(30,'liyun','123456','李云',1,'13309090030',NULL,NULL,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2020-03-01',NULL,'2023-10-20 16:35:33','2023-10-20 16:36:31'),(36,'linghuchong','123456','令狐冲',1,'18809091212',2,6800,'https://web-framework.oss-cn-hangzhou.aliyuncs.com/2023/1.jpg','2023-10-19',2,'2023-10-20 20:44:54','2023-11-09 09:41:04');​
-- 员工工作经历信息
create table emp_expr(id int unsigned primary key auto_increment comment 'ID, 主键',emp_id int unsigned comment '员工ID',begin date comment '开始时间',end  date comment '结束时间',company varchar(50) comment '公司名称',job varchar(50) comment '职位'
)comment '工作经历';

2.准备实体类Emp、EmpExpr

package com.itheima.pojo;
​
import lombok.Data;
​
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.List;
​
@Data
public class Emp {private Integer id; //ID,主键private String username; //用户名private String password; //密码private String name; //姓名private Integer gender; //性别, 1:男, 2:女private String phone; //手机号private Integer job; //职位, 1:班主任,2:讲师,3:学工主管,4:教研主管,5:咨询师private Integer salary; //薪资private String image; //头像private LocalDate entryDate; //入职日期private Integer deptId; //关联的部门IDprivate LocalDateTime createTime; //创建时间private LocalDateTime updateTime; //修改时间
​//封装部门名称数private String deptName; //部门名称
}package com.itheima.pojo;
​
import lombok.Data;
​
import java.time.LocalDate;
​
/*** 工作经历*/
@Data
public class EmpExpr {private Integer id; //IDprivate Integer empId; //员工IDprivate LocalDate begin; //开始时间private LocalDate end; //结束时间private String company; //公司名称private String job; //职位
}

3.准备三层架构的基本代码结构:EmpController、EmpService/EmpServiceImpl、EmpMapper。

EmpMapper:

package com.itheima.mapper;
​
import com.itheima.pojo.Emp;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
​
@Mapper
public interface EmpMapper {
​
}

EmpService:

package com.itheima.service;
​
public interface EmpService {
}

EmpServiceImpl:

package com.itheima.service.impl;
​
import com.itheima.mapper.EmpMapper;
import com.itheima.service.EmpService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
​
/*** 员工管理*/
@Service
public class EmpServiceImpl implements EmpService {
​@Autowiredprivate EmpMapper empMapper;
​
}

EmpController:

package com.itheima.controller;
​
import com.itheima.service.EmpService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RestController;
​
/*** 员工管理*/
@Slf4j
@RestController
public class EmpController {
​@Autowiredprivate EmpService empService;
​
}

分页查询:

1.原始方式:

分析:

三层架构中,每一层的职责如下:

1.Controller:接收参数(分页);调用service,进行分页查询,获取PageResult;响应结果。

具体实现:

/*** 分页查询*/
@GetMapping
public Result page (@RequestParam(defaultValue = "1") Integer page,@RequestParam(defaultValue = "10") Integer pageSize){log.info("分页查询:{},{}",page,pageSize);PageResult<Emp> pageResult = empService.page(page,pageSize);return Result.success(pageResult);
}

2.Service:调用Mapper接口,查询总记录数;调用Mapper接口,查询结果列表;封装PageResult对象,返回。

public PageResult<Emp> page(Integer page, Integer pageSize) {//1.调用Mapper接口,查询总记录数Long total = empMapper.count();
​//2.调用Mapper接口,查询结果列表Integer start = (page-1)*pageSize;List<Emp> rows = empMapper.list(start, pageSize);
​//3.封装结果PageResultreturn new PageResult<Emp>(total,rows);
}

3.Mapper:SQL:

select e.*,d.name from emp e left join dept d on e.dept_id = d.id limit 0,5;
select count(*) from emp e left join dept d on e.dept_id = d.id;

具体实现:

@Mapper
public interface EmpMapper {/*** 查询符合条件的总记录数*/@Select("select count(*) from emp e left join dept d on e.dept_id = d.id;")public Long count();
​/***分页查询*/@Select("select e.*,d.name deptName from emp e left join dept d on e.dept_id = d.id order by e.update_time limit #{start},#{pageSize};")public List<Emp> list(Integer start,Integer pageSize);
}

2.PageHelper分页插件:

PageHelper是第三方提供的在Mybatis框架中用来实现分页的插件,用来简化分页操作,提高开发效率。

使用步骤:

1.引入PageHelper的依赖

<!--分页插件PageHelper-->
<dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper-spring-boot-starter</artifactId><version>1.4.7</version>
</dependency>

2.定义Mapper接口接口的查询方法(无需考虑分页)

@Select("select e.*,d.name deptName from emp e left join dept d on e.dept_id = d.id order by e.update_time desc")
public List<Emp> list();

3.在service方法中实现分页查询

/*** PageHelper分页查询* @param page 页码* @param pageSize 每页的记录数*/
@Override
public PageResult<Emp> page(Integer page, Integer pageSize) {//1.设置分页参数(PageHelper)PageHelper.startPage(page,pageSize);
​//2.执行查询List<Emp> empList = empMapper.list();
​//3.解析查询结果,并封装Page<Emp> p = (Page<Emp>) empList;return new PageResult<Emp>(p.getTotal(),p.getResult());
​
}

(为什么empList可以强转为Page<emp>)

PageHelper实现机制:

PageHelper注意事项:

1.定义的SQL语句结尾不能加分号;

2.PageHelper仅仅能对紧跟其后的第一个查询语句进行分页处理

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