后端：Spring Boot生成Excel文件添加依赖

1. 在pom.xml中添加Apache POI的依赖：

      org.apache.poi
      poi
      5.1.0
   
      org.apache.poi
      poi-ooxml
      5.1.0
   

2. 创建一个用于生成Excel文件的方法

   import org.apache.poi.ss.usermodel.*;
   import org.apache.poi.xssf.usermodel.XSSFWorkbook;
   import java.io.ByteArrayInputStream;
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.io.InputStream;
   import java.util.List;
   public class ExcelUtil {
       public static InputStream generateExcel(List> data) throws IOException {
           Workbook workbook = new XSSFWorkbook();
           Sheet sheet = workbook.createSheet("Sheet1");
           for (int i = 0; i< data.size(); i++) {
               Row row = sheet.createRow(i);
               List rowData = data.get(i);
               for (int j = 0; j < rowData.size(); j++) {
                   Cell cell = row.createCell(j);
                   cell.setCellValue(rowData.get(j));
               }
           }
           ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
           workbook.write(outputStream);
           workbook.close();
           return new ByteArrayInputStream(outputStream.toByteArray());
       }
   }

        4.创建一个用于处理Excel文件的Controller

1. import org.springframework.web.bind.annotation.PostMapping;
   import org.springframework.web.bind.annotation.RequestBody;
   import org.springframework.web.bind.annotation.RestController;
   import javax.servlet.http.HttpServletResponse;
   import java.io.IOException;
   import java.util.List;
   @RestController
   public class ExcelController {
       @PostMapping("/generateExcel")
       public void generateExcel(@RequestBody List> data, HttpServletResponse response) throws IOException {
           InputStream inputStream = ExcelUtil.generateExcel(data);
           response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
           response.setHeader("Content-Disposition", "attachment; filename=data.xlsx");
           response.setHeader("Cache-Control", "no-cache");
           byte[] buffer = new byte[1024];
           int bytesRead;
           while ((bytesRead = inputStream.read(buffer)) != -1) {
               response.getOutputStream().write(buffer, 0, bytesRead);
           }
           inputStream.close();
       }
   }

前端：微信小程序上送数据并下载Excel文件

1. 在app.json中添加一个用于下载Excel文件的页面：

   {
     "pages": [
       "pages/index/index",
       "pages/download/download"
     ]
   }

2. 在pages/download目录下创建download.wxml和download.wxss文件，用于显示下载按钮和提示信息

   
   
    下载Excel
     {{info}}
   

   /* download.wxss */
   .container {
     display: flex;
     flex-direction: column;
     align-items: center;
     justify-content: center;
     height: 100%;
   }
   .download-btn {
     margin-bottom: 20rpx;
   }
   .info {
     text-align: center;
   }

3. 在pages/download目录下创建download.js文件，用于处理下载Excel文件的逻辑：

   Page({
     data: {
       info: ''
     },
     downloadExcel: function () {
       const that = this;
       const data = [
         ['姓名', '年龄', '性别'],
         ['张三', '25', '男'],
         ['李四', '30', '女']
       ];
       wx.request({
         url: 'https://your-spring-boot-server.com/generateExcel',
         method: 'POST',
         data: data,
         responseType: 'arraybuffer',
         success: function (res) {
           const filePath = wx.env.USER_DATA_PATH + '/data.xlsx';
           wx.getFileSystemManager().writeFile({
             filePath: filePath,
             data: res.data,
             encoding: 'binary',
             success: function () {
               wx.downloadFile({
                 filePath: filePath,
                 success: function (res) {
                   that.setData({ info: '下载成功' });
                 },
                 fail: function () {
                   that.setData({ info: '下载失败' });
                 }
               });
             },
             fail: function () {
               that.setData({ info: '写入文件失败' });
             }
           });
         },
         fail: function () {
           that.setData({ info: '请求失败' });
         }
       });
     }
   });

   请注意将url中的域名替换为您的Spring Boot服务器的域名。

   现在，当用户点击下载按钮时，微信小程序会将数据上送到Spring Boot服务器，服务器生成Excel文件并返回给小程序，小程序将文件保存到本地并下载。