Springboot 练习

        Springboot练习——分页查询

        Emp类

package com.wzb.pojo20240930;import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;import java.time.LocalDate;
import java.time.LocalDateTime;@Data
@NoArgsConstructor
@AllArgsConstructor
public class Emp {private Integer id;private String username;private String password;private String name;private Short gender;private String image;private Short job;private LocalDate entrydate;private Integer deptId;private LocalDateTime createTime;private LocalDateTime updateTime;
}

        查询封装的PageBean类

package com.wzb.pojo20240930;import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;import java.util.List;@Data
@NoArgsConstructor
@AllArgsConstructor
public class PageBean {private Long total;private List<Emp> rows;
}

         查询返回的Result类

package com.wzb.pojo20240930;import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@NoArgsConstructor
@AllArgsConstructor
public class Result {private Integer code; // 响应码，1是响应成功，2是响应失败private String message; // 响应信息，描述响应结果的字符串private Object data; // 响应返回的数据// 响应成功，但不返回数据的方法public static Result success() {return new Result(1, "success", null);}// 响应成功，并且返回数据的方法public static Result success(Object data) {return new Result(1,"success", data);}// 响应失败的方法public static Result fail(String message) {return new Result(0, message, null);}
}

        Controller

package com.wzb.controller;import com.wzb.pojo20240930.Emp;
import com.wzb.pojo20240930.PageBean;
import com.wzb.pojo20240930.Result;
import com.wzb.service.EmpService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;import java.time.LocalDate;
import java.util.List;@RestController
public class EmpController {@Autowiredprivate EmpService empService;@GetMapping("/emps")// @RequestParam接收前端传递的想要查询的页数和每一页的记录数public Result pageSelect(@RequestParam(defaultValue = "1") Integer page,@RequestParam(defaultValue = "10") Integer pageSize,String name, Short gender,// 因为Http请求的路径全部都是字符串，所以说要用@DateTimeFormat注解并限定其格式将String解析为LocalDate@DateTimeFormat(pattern = ("yyyy-MM-dd")) LocalDate begin,@DateTimeFormat(pattern = ("yyyy-MM-dd")) LocalDate end) {// 日志记录System.out.println("进行了一次条件查询");// 通过Service层，操作数据库，并将查询的数据封装到PageBean中返回PageBean pageBean = empService.pageSelect(page, pageSize, name, gender, begin, end);return Result.success(pageBean);}}

        Service

package com.wzb.service;import com.wzb.pojo20240930.Emp;
import com.wzb.pojo20240930.PageBean;import java.time.LocalDate;
import java.util.List;public interface EmpService {PageBean pageSelect(Integer page, Integer pageSize, String name, Short gender, LocalDate begin, LocalDate end);
}

        实现类

package com.wzb.service;import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import com.wzb.mapper.EmpMapper;
import com.wzb.pojo20240930.Emp;
import com.wzb.pojo20240930.PageBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.time.LocalDate;
import java.util.List;@Service
public class EmpServiceImplement implements EmpService{@Autowiredprivate EmpMapper empMapper;@Overridepublic PageBean pageSelect(Integer page, Integer pageSize, String name, Short gender,LocalDate begin, LocalDate end) {// 使用分页插件PageHelper.startPage(page, pageSize);// 调用mapper中的方法查询并返回List<Emp> empList = empMapper.pageSelect(name, gender, begin, end);Page<Emp> p = (Page<Emp>) empList;return new PageBean(p.getTotal(), p.getResult());}
}

        Mapper

package com.wzb.mapper;import com.wzb.pojo20240930.Emp;
import org.apache.ibatis.annotations.Mapper;import java.time.LocalDate;
import java.util.List;@Mapper
public interface EmpMapper {List<Emp> pageSelect(String name, Short gender, LocalDate begin, LocalDate end);
}

        XML配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.wzb.mapper.EmpMapper"><!-- 执行条件分页查询 --><!-- 条件分页查询 --><select id="pageSelect" resultType="com.wzb.pojo20240930.Emp">select * from emp<where><if test="name != null and name != ''">name like concat('%',#{name},'%')</if><if test="gender != null">and gender = #{gender}</if><if test="begin != null and end != null">and entrydate between #{begin} and #{end}</if></where>order by update_time desc</select>
</mapper>