ADD file via upload

FileUploadController.java

@@ -0,0 +1,113 @@
+package com.example.classroomattendance.controller;
+
+import com.example.classroomattendance.model.Student;
+import com.example.classroomattendance.service.StudentService;
+import org.apache.poi.ss.usermodel.*;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.*;
+import org.springframework.web.multipart.MultipartFile;
+
+import java.io.IOException;
+import java.text.DecimalFormat;
+import java.util.ArrayList;
+import java.util.List;
+
+@Controller
+public class FileUploadController {
+
+    @Autowired
+    private StudentService studentService;
+
+    @PostMapping("/upload")
+    public String handleFileUpload(@RequestParam("file") MultipartFile file, Model model) {
+        if (file.isEmpty()) {
+            model.addAttribute("message", "文件为空");
+            return "index";
+        }
+
+        try {
+            List<Student> students = parseExcel(file);
+            studentService.addStudents(students);
+            model.addAttribute("message", "文件接收成功");
+            model.addAttribute("students", students);
+            model.addAttribute("uploadSuccess", true); // 添加标志以显示下一步按钮
+            return "index"; // 返回 index 视图
+        } catch (IOException ex) {
+            ex.printStackTrace();
+            model.addAttribute("message", "文件处理失败: " + ex.getMessage());
+            return "index";
+        } catch (Exception ex) {
+            ex.printStackTrace();
+            model.addAttribute("message", "未知错误: " + ex.getMessage());
+            return "index";
+        }
+    }
+
+    private List<Student> parseExcel(MultipartFile file) throws IOException {
+        List<Student> students = new ArrayList<>();
+        Workbook workbook = WorkbookFactory.create(file.getInputStream());
+        Sheet sheet = workbook.getSheetAt(0);
+
+        for (Row row : sheet) {
+            if (row.getRowNum() == 0) {
+                continue; // 跳过标题行
+            }
+
+            Cell nameCell = row.getCell(0);
+            Cell studentIdCell = row.getCell(1);
+            Cell pointsCell = row.getCell(2);
+
+            if (nameCell == null || studentIdCell == null) {
+                continue; // 跳过不完整的记录
+            }
+
+            Student student = new Student();
+            student.setId((long) row.getRowNum()); // 使用行号作为 ID 示例
+
+            student.setName(getCellStringValue(nameCell));
+            student.setStudentId(getCellStringValue(studentIdCell));
+            student.setPoints(getCellDoubleValue(pointsCell));
+
+            students.add(student);
+        }
+
+        workbook.close();
+        return students;
+    }
+
+    private String getCellStringValue(Cell cell) {
+        if (cell == null) {
+            return "";
+        }
+        switch (cell.getCellType()) {
+            case STRING:
+                return cell.getStringCellValue();
+            case NUMERIC:
+                // 对于学号这种需要转换为字符串的情况，使用 DecimalFormat 保证不使用科学计数法
+                DecimalFormat df = new DecimalFormat("0");
+                return df.format(cell.getNumericCellValue());
+            default:
+                return cell.toString();
+        }
+    }
+
+    private double getCellDoubleValue(Cell cell) {
+        if (cell == null) {
+            return 0.0;
+        }
+        switch (cell.getCellType()) {
+            case NUMERIC:
+                return cell.getNumericCellValue();
+            case STRING:
+                try {
+                    return Double.parseDouble(cell.getStringCellValue());
+                } catch (NumberFormatException e) {
+                    return 0.0;
+                }
+            default:
+                return 0.0;
+        }
+    }
+}