按照以往开发一个新模块的套路，首先应该把分页数据展示出来，然后再实现该模块的添加、修改和删除功能。本小节咱们把查询罚款分页数据的后端代码给实现了，下节课就可以写前端代码了。

一、编写持久层

在TbAmectDao.xml文件中，我们定义SQL语句。

<select id="searchAmectByPage" parameterType="HashMap" resultType="HashMap">
    SELECT a.id,
           a.uuid,
           u.name,
           d.dept_name AS deptName,
           a.amount,
           a.reason,
           `at`.type,
           a.`status`,
           DATE_FORMAT(a.create_time,'%Y-%m-%d %H:%i') AS createTime,
           IF(a.user_id=#{currentUserId},"true","false") AS mine
    FROM tb_amect a
    JOIN tb_amect_type `at` ON a.type_id = `at`.id
    JOIN tb_user u ON u.id = a.user_id
    JOIN tb_dept d ON u.dept_id = d.id
    WHERE 1=1
    <if test="userId != null">
        AND u.id = #{userId}
    </if>
    <if test="name != null">
        AND u.name LIKE '%${name}%'
    </if>
    <if test="deptId != null">
        AND u.dept_id = #{deptId}
    </if>
    <if test="typeId != null">
        AND at.id = #{typeId}
    </if>
    <if test="startDate != null and endDate != null">
        AND a.create_time BETWEEN #{startDate} AND #{endDate}
    </if>
    <if test="status!=null">
        AND a.`status` = #{status}
    </if>
    ORDER BY a.id DESC
    LIMIT #{start}, #{length}
</select>

<select id="searchAmectCount" parameterType="HashMap" resultType="long">
    SELECT COUNT(*)
    FROM tb_amect a
    JOIN tb_amect_type `at` ON a.type_id = `at`.id
    JOIN tb_user u ON u.id = a.user_id
    JOIN tb_dept d ON u.dept_id = d.id
    WHERE 1=1
    <if test="userId != null">
        AND u.id = #{userId}
    </if>
    <if test="name != null">
        AND u.name LIKE '%${name}%'
    </if>
    <if test="deptId != null">
        AND u.dept_id = #{deptId}
    </if>
    <if test="typeId != null">
        AND at.id = #{typeId}
    </if>
    <if test="startDate != null and endDate != null">
        AND a.create_time BETWEEN #{startDate} AND #{endDate}
    </if>
    <if test="status!=null">
        AND a.`status` = #{status}
    </if>
</select>

在TbAmectDao.java接口中，定义DAO方法。

public interface TbAmectDao {
    public ArrayList<HashMap> searchAmectByPage(HashMap param);
    public long searchAmectCount(HashMap param);
}

二、编写业务层代码

创建AmectService.java接口，定义抽象方法。

public interface AmectService {
    public PageUtils searchAmectByPage(HashMap param);
}

创建AmectServiceImpl.java类，实现抽象方法。

@Service
@Slf4j
public class AmectServiceImpl implements AmectService {
    @Autowired
    private TbAmectDao amectDao;
    
    @Override
    public PageUtils searchAmectByPage(HashMap param) {
        ArrayList<HashMap> list = amectDao.searchAmectByPage(param);
        long count = amectDao.searchAmectCount(param);
        int start = (Integer) param.get("start");
        int length = (Integer) param.get("length");
        PageUtils pageUtils = new PageUtils(list, count, start, length);
        return pageUtils;
    }
}

三、编写Web层代码

创建SearchAmectByPageForm.java类，封装Ajax提交的数据。

@Data
@Schema(description = "查询罚款分页记录表单")
public class SearchAmectByPageForm {

    @Pattern(regexp = "^[\\u4e00-\\u9fa5]{1,10}$", message = "name内容不正确")
    @Schema(description = "姓名")
    private String name;

    @Min(value = 1, message = "deptId不能小于1")
    @Schema(description = "部门编号")
    private Integer deptId;

    @Min(value = 1, message = "typeId不能小于1")
    @Schema(description = "罚款类型编号")
    private Integer typeId;

    @Pattern(regexp = "^((((1[6-9]|[2-9]\\d)\\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\\d|3[01]))|(((1[6-9]|[2-9]\\d)\\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\\d|30))|(((1[6-9]|[2-9]\\d)\\d{2})-0?2-(0?[1-9]|1\\d|2[0-8]))|(((1[6-9]|[2-9]\\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$", message = "startDate内容不正确")
    @Schema(description = "开始日期")
    private String startDate;

    @Pattern(regexp = "^((((1[6-9]|[2-9]\\d)\\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\\d|3[01]))|(((1[6-9]|[2-9]\\d)\\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\\d|30))|(((1[6-9]|[2-9]\\d)\\d{2})-0?2-(0?[1-9]|1\\d|2[0-8]))|(((1[6-9]|[2-9]\\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$", message = "endDate内容不正确")
    @Schema(description = "截止日期")
    private String endDate;

    @Min(value = 1, message = "status不能小于1")
    @Schema(description = "状态")
    private Byte status;

    @NotNull(message = "page不能为空")
    @Min(value = 1, message = "page不能小于1")
    @Schema(description = "页数")
    private Integer page;

    @NotNull(message = "length不能为空")
    @Range(min = 10, max = 50, message = "length必须为10~50之间")
    @Schema(description = "每页记录数")
    private Integer length;

}

创建AmectController.java类，定义Web方法。

@RestController
@RequestMapping("/amect")
@Tag(name = "AmectController", description = "罚款Web接口")
@Slf4j
public class AmectController {
    @Autowired
    private AmectService amectService;
    
    @PostMapping("/searchAmectByPage")
    @Operation(summary = "查询罚款分页记录")
    @SaCheckLogin
    public R searchAmectByPage(@Valid @RequestBody SearchAmectByPageForm form) {
        if ((form.getStartDate() != null && form.getEndDate() == null) || (form.getStartDate() == null && form.getEndDate() != null)) {
            return R.error("startDate和endDate只能同时为空，或者不为空");
        }

        int page = form.getPage();
        int length = form.getLength();
        int start = (page - 1) * length;
        HashMap param = JSONUtil.parse(form).toBean(HashMap.class);
        param.put("start", start);
        param.put("currentUserId", StpUtil.getLoginIdAsInt());
        if (!(StpUtil.hasPermission("AMECT:SELECT") || StpUtil.hasPermission("ROOT"))) {
            param.put("userId", StpUtil.getLoginIdAsInt());
        }

        PageUtils pageUtils = amectService.searchAmectByPage(param);
        return R.ok().put("page", pageUtils);
    }

}

正常情况下，线上或者线下会议结束后，系统会自动生成未出席会议人员的罚款单。所以tb_amect表中会有记录，所以我们用Swagger来测试Web方法，看看能否查询出来分页记录。