学习进度条

今日所花时间：一小时
今日代码量：100行
博客量：1篇
了解到的知识点： 数据的分页查询，借助写好的PageBean工具类
PageBean

package com.example.littlebabydemo0425.pojo;

import lombok.Data;

import java.util.List;

//分页返回结果对象
@Data

public class PageBean<T>{
    private Long total;//总条数
    private List<T> items;//当前页数据集合

    public PageBean() {
    }

    public PageBean(Long total, List<T> items) {
        this.total = total;
        this.items = items;
    }

    public Long getTotal() {
        return total;
    }

    public void setTotal(Long total) {
        this.total = total;
    }

    public List<T> getItems() {
        return items;
    }

    public void setItems(List<T> items) {
        this.items = items;
    }
}

示例：设备列表查询
实体类：Device

package com.example.littlebabydemo0425.pojo;


import jakarta.persistence.*;
import java.util.Date;

@Entity
@Table(name = "device", uniqueConstraints = {
        @UniqueConstraint(columnNames = "device_code", name = "idx_device_code")
})
public class Device {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "device_code", length = 64, nullable = false)
    private String deviceCode;

    @Column(name = "device_name", length = 128, nullable = false)
    private String deviceName;

    @Column(name = "device_type", length = 32, nullable = false)
    private String deviceType;

    @Column(name = "location", length = 256)
    private String location;

    @Column(name = "status", columnDefinition = "tinyint default 1")
    private Integer status;

    @Column(name = "create_time", columnDefinition = "datetime default CURRENT_TIMESTAMP")
    private Date createTime;

    @Column(name = "update_time", columnDefinition = "datetime default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP")
    private Date updateTime;


    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getDeviceCode() {
        return deviceCode;
    }

    public void setDeviceCode(String deviceCode) {
        this.deviceCode = deviceCode;
    }

    public String getDeviceName() {
        return deviceName;
    }

    public void setDeviceName(String deviceName) {
        this.deviceName = deviceName;
    }

    public String getDeviceType() {
        return deviceType;
    }

    public void setDeviceType(String deviceType) {
        this.deviceType = deviceType;
    }

    public String getLocation() {
        return location;
    }

    public void setLocation(String location) {
        this.location = location;
    }

    public Integer getStatus() {
        return status;
    }

    public void setStatus(Integer status) {
        this.status = status;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    public Date getUpdateTime() {
        return updateTime;
    }

    public void setUpdateTime(Date updateTime) {
        this.updateTime = updateTime;
    }
}

DeviceController

package com.example.littlebabydemo0425.controller;

import com.example.littlebabydemo0425.mapper.DeviceMapper;
import com.example.littlebabydemo0425.pojo.Device;
import com.example.littlebabydemo0425.pojo.PageBean;
import com.example.littlebabydemo0425.pojo.Result;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/devices/")
@CrossOrigin(origins = "http://localhost:5173") // 添加CORS支持
public class DevicesController {
    @Autowired
    private DeviceMapper deviceMapper;
    @GetMapping
    public Result<PageBean<Device>> list(Integer pageNum,
                                         Integer pageSize,
                                         @RequestParam(required = false)String deviceCode,
                                         @RequestParam(required = false)String deviceType,
                                         @RequestParam(required = false)String deviceName,
                                         @RequestParam(required = false) String status){
        PageBean<Device>  pb = deviceMapper.list(pageNum,pageSize,deviceCode,deviceType,deviceName,status);
        return Result.success(pb);
    }
    @DeleteMapping("/{deviceCode}")
    public Result<String> deleteDevice(@PathVariable String  deviceCode) {
        deviceMapper.deleteById(deviceCode);
        return Result.success(deviceCode);
    }

    @PostMapping
    public ResponseEntity<Result<Device>> createDevice(@RequestBody Device device) {
        try {
            // 检查设备编号是否已存在
            Device existingDevice = deviceMapper.selectByDeviceCode(device.getDeviceCode());
            if (existingDevice != null) {
                return ResponseEntity.status(HttpStatus.CONFLICT)
                        .body(Result.error("设备编号已存在"));
            }
            System.out.println("收到请求，设备数据: " + device); // 调试日志

            if(device.getDeviceCode() == null) {
                return ResponseEntity.badRequest()
                        .body(Result.error("设备编号不能为空"));
            }

            // 设置默认状态为1（正常）
            if (device.getStatus() == null) {
                device.setStatus(1);
            }

            // 插入新设备
            int result = deviceMapper.insert(device);
            if (result > 0) {
                return ResponseEntity.status(HttpStatus.CREATED)
                        .body(Result.success(device));
            } else {
                return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                        .body(Result.error("添加设备失败"));
            }
        } catch (Exception e) {
            e.printStackTrace();
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                    .body(Result.error("服务器内部错误: " + e.getMessage()));
        }
    }

}

DeviceMapper

package com.example.littlebabydemo0425.mapper;

import com.example.littlebabydemo0425.pojo.Device;
import com.example.littlebabydemo0425.pojo.PageBean;
import org.apache.ibatis.annotations.*;
import org.apache.ibatis.jdbc.SQL;

import java.util.List;

@Mapper
public interface DeviceMapper {
    @Insert("INSERT INTO device (device_code, device_name, device_type, location, status) " +
            "VALUES(#{deviceCode}, #{deviceName}, #{deviceType}, #{location}, #{status})")
    @Options(useGeneratedKeys = true, keyProperty = "id")
    int insert(Device device);

    @Update("UPDATE device SET device_name=#{deviceName}, device_type=#{deviceType}, " +
            "location=#{location}, status=#{status} WHERE id=#{id}")
    int update(Device device);

    @Delete("DELETE FROM device WHERE device_code=#{deviceCode}")
    int deleteById(String deviceCode);

    @Select("SELECT * FROM device WHERE id=#{id}")
    Device selectById(Long id);

    @Select("SELECT * FROM device WHERE device_code=#{deviceCode}")
    Device selectByDeviceCode(String deviceCode);

    @Select("SELECT * FROM device")
    List<Device> selectAll();

    /**
     * 分页查询设备列表
     * @param pageNum 页码
     * @param pageSize 每页大小
     * @param deviceCode 设备编码(可选)
     * @param deviceName 设备名称(可选)
     * @param deviceType 设备类型(可选)
     * @param status 设备状态(可选)
     * @return 分页结果
     */
    default PageBean<Device> list(Integer pageNum, Integer pageSize, String deviceCode, String deviceType,String deviceName,  String status) {
        PageBean<Device> pb = new PageBean<>();

        // 计算偏移量
        int offset = (pageNum - 1) * pageSize;

        // 查询数据
        List<Device> devices = selectByCondition(deviceCode, deviceType,deviceName,  status, offset, pageSize);
        pb.setItems(devices);

        // 查询总数
        long total = countByCondition(deviceCode, deviceType, deviceName,  status);
        pb.setTotal(total);

        return pb;
    }

    @SelectProvider(type = DeviceSqlProvider.class, method = "selectByCondition")
    List<Device> selectByCondition(
            @Param("deviceCode") String deviceCode,
            @Param("deviceType") String deviceType,
            @Param("deviceName") String deviceName,
            @Param("status") String status,
            @Param("offset") int offset,
            @Param("pageSize") int pageSize);

    @SelectProvider(type = DeviceSqlProvider.class, method = "countByCondition")
    long countByCondition(
            @Param("deviceCode") String deviceCode,
            @Param("deviceType") String deviceType,
            @Param("deviceName") String deviceName,
            @Param("status") String status);

    // SQL提供类
    class DeviceSqlProvider {
        public String selectByCondition(
                @Param("deviceCode") String deviceCode,
                @Param("deviceType") String deviceType,
                @Param("deviceName") String deviceName,
                @Param("status") String status,
                @Param("offset") int offset,
                @Param("pageSize") int pageSize) {
            return new SQL() {{
                SELECT("*");
                FROM("device");
                if (deviceCode != null && !deviceCode.isEmpty()) {
                    WHERE("device_code LIKE CONCAT('%', #{deviceCode}, '%')");
                }
                if (deviceType != null && !deviceType.isEmpty()) {
                    // 修改为根据设备类型进行模糊匹配
                    WHERE("device_type LIKE CONCAT('%', #{deviceType}, '%')");
                }
                if (deviceName != null && !deviceName.isEmpty()) {
                    WHERE("device_name LIKE CONCAT('%', #{deviceName}, '%')");
                }

                if (status != null && !status.isEmpty()) {
                    WHERE("status = #{status}");
                }
                ORDER_BY("id DESC");
            }}.toString() + " LIMIT #{offset}, #{pageSize}";
        }

        public String countByCondition(
                @Param("deviceCode") String deviceCode,
                @Param("deviceType") String deviceType,
                @Param("deviceName") String deviceName,

                @Param("status") String status) {
            return new SQL() {{
                SELECT("COUNT(*)");
                FROM("device");
                if (deviceCode != null && !deviceCode.isEmpty()) {
                    WHERE("device_code LIKE CONCAT('%', #{deviceCode}, '%')");
                }
                if (deviceType != null && !deviceType.isEmpty()) {
                    // 修改为根据设备类型进行模糊匹配
                    WHERE("device_type LIKE CONCAT('%', #{deviceType}, '%')");
                }
                if (deviceName != null && !deviceName.isEmpty()) {
                    WHERE("device_name LIKE CONCAT('%', #{deviceName}, '%')");
                }

                if (status != null && !status.isEmpty()) {
                    WHERE("status = #{status}");
                }
            }}.toString();
        }
    }
}

根据以上代码，能够完成设备列表的信息分页查询和显示，当然还能够根据设备类型，设备名称，设备编号，设备状态进行条件查询