2后端JAVA：下载数据库数据到EXCEL表格？代码
这是运用kimi，cursor写出来的后端基础增删改查代码心得系列。
将从如何用cursor写出代码，修改cursor写出来的代码，连接数据库，上传下载代码等等方面展开。
第一集：
后端JAVA：Cursor与kimi如何结合？Cursor写出的代码出现哪些bug？-CSDN博客
下载代码：
/**
* 下载数据库数据
* 总情况：将数据库中的合同信息导出为Excel文件
* @param response HTTP响应对象
* @throws Exception 可能抛出的异常
*/
@GetMapping("/download")
@ApiOperation("下载数据库数据")
public void download(HttpServletResponse response) throws Exception {
// 查询多表数据
List list = contractsService.getContractsDetails();
// 在内存操作，写到浏览器
ExcelWriter writer = ExcelUtil.getWriter(true);
// 自定义标题别名
writer.addHeaderAlias("contractId", "序号");
writer.addHeaderAlias("campus", "所在校区");
writer.addHeaderAlias("address", "坐落地址");
writer.addHeaderAlias("propertyName", "房产名称（铺位号）");
writer.addHeaderAlias("tenantName", "租户");
writer.addHeaderAlias("contactNumber", "联系电话");
writer.addHeaderAlias("tenantInfo", "租户信息");
writer.addHeaderAlias("area", "房屋面积（平方米）");
writer.addHeaderAlias("contractDuration", "合同年限");
writer.addHeaderAlias("contractCode", "合同编码");
writer.addHeaderAlias("totalContractAmount", "合同总金额");
writer.addHeaderAlias("contractStartDate", "合同期起");
writer.addHeaderAlias("contractEndDate", "合同期止");
writer.addHeaderAlias("yearOfRentReceivable", "应收租金年份");
writer.addHeaderAlias("rentalPeriodStart", "本次应收租金期起");
writer.addHeaderAlias("rentalPeriodEnd", "本次应收租金期止");
writer.addHeaderAlias("currentRentReceived", "本次应收租金");
writer.addHeaderAlias("currentRentDue", "本次实收租金");
writer.addHeaderAlias("currentRentUnpaid", "本次未收租金");
//writer.addHeaderAlias("currentRentReceived", "本次应收已收租金");
writer.addHeaderAlias("rentReceivedDate", "收取租金时间");
writer.addHeaderAlias("remarks", "备注");
writer.addHeaderAlias("rentSubmittedToSchool", "已上交学校租金");
writer.addHeaderAlias("rentNotSubmittedToSchool", "未上交学校租金");
writer.addHeaderAlias("rentSubmissionDate", "租金上交学校时间");
writer.addHeaderAlias("requiredDeposit", "应交押金");
writer.addHeaderAlias("paidDeposit", "已交押金");
writer.addHeaderAlias("depositEntryDate", "押金进账日期");
// 写入数据
writer.write(list, true);
// 设置content-type
response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=utf-8");
String fileName = URLEncoder.encode("合同信息", "UTF-8");
response.setHeader("Content-Disposition", "attachment;filename=" + fileName + ".xlsx");
ServletOutputStream outputStream = response.getOutputStream();
writer.flush(outputStream, true);
outputStream.close();
writer.close();
}
这里要注意的事项是：
1.writer.addHeaderAlias("contractId", "序号"); 先写contractId，再写序号
2.要有对应的实体类
package com.ams;
import com.baomidou.mybatisplus.annotation.TableId;
import io.swagger.annotations.ApiModel;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.math.BigDecimal;
import java.time.LocalDate;
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class DownloadDTO {
@TableId
private Integer contractId;
// private Integer propertyId;
// private Integer tenantId;
private String contractCode;
private LocalDate contractStartDate;
private LocalDate contractEndDate;
private Long contractDuration;
private BigDecimal requiredDeposit;
private BigDecimal paidDeposit;
private LocalDate depositEntryDate;
private BigDecimal totalContractAmount;
private String campus;
private String address;
private String propertyName;
private BigDecimal area;
private LocalDate rentalPeriodStart;
private LocalDate rentalPeriodEnd;
private BigDecimal currentRentDue;
private BigDecimal currentRentUnpaid;
private LocalDate rentReceivedDate;
private String remarks;
private BigDecimal rentSubmittedToSchool;
private BigDecimal rentNotSubmittedToSchool;
private LocalDate rentSubmissionDate;
private String yearOfRentReceivable;
private BigDecimal currentRentReceived;
private String tenantName;
private String contactNumber;
private String tenantInfo;
} 3.对应的ServiceImpl，Service层
/**
* 查询合同详情信息
* 总情况：查询合同详情信息，用于导出
* @return 查询结果
*/
List getContractsDetails(); /**
* 查询合同详情信息
* 总情况：查询合同详情信息，用于导出
* @return 查询结果
*/
@Override
public List getContractsDetails() {
return contractsMapper.findContractsDetails(); // 调用多表查询
} 4.对应的mapper层，mapper
/**
* 查询合同详情信息
* 总情况：查询合同详情信息，用于导出
* @return 查询结果
*/
List findContractsDetails(); 这里用到的是多表联查。
5.用到的pom，这里要注意，父pom和子pom都要引用
cn.hutool
hutool-all
5.7.20
org.apache.poi
poi-ooxml
4.1.2
6.效果如图
以及下面的数据库信息（这里不作展示）