feat:新增导出与模板功能，另：现在可以兼容excel

src/main/java/com/example/attendance/controller/StudentController.java

@@ -3,11 +3,20 @@ package com.example.attendance.controller;
 import com.example.attendance.entity.PointsRequest;
 import com.example.attendance.entity.Student;
 import com.example.attendance.service.StudentService;
+import jakarta.servlet.http.HttpServletResponse;
+import org.apache.poi.ss.usermodel.Row;
+import org.apache.poi.ss.usermodel.Sheet;
+import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
 import org.springframework.web.multipart.MultipartFile;
 
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
 import java.util.List;
 
 @RestController
@@ -105,4 +114,55 @@ public class StudentController {
             return "学生数据导入失败：" + e.getMessage();
         }
     }
+    /*导入学生数据
+     */
+    @GetMapping("/export-students")
+    public ResponseEntity<byte[]> exportStudents() throws IOException {
+        List<Student> students = studentService.findAll(); // 获取所有学生数据
+
+        // 创建 Excel 工作簿
+        Workbook workbook = new XSSFWorkbook();
+        Sheet sheet = workbook.createSheet("Students");
+
+        // 创建表头
+        Row header = sheet.createRow(0);
+        header.createCell(0).setCellValue("学号");
+        header.createCell(1).setCellValue("姓名");
+        header.createCell(2).setCellValue("积分");
+
+        // 填充数据
+        int rowNum = 1;
+        for (Student student : students) {
+            Row row = sheet.createRow(rowNum++);
+            row.createCell(0).setCellValue(student.getStudentNumber());
+            row.createCell(1).setCellValue(student.getName());
+            row.createCell(2).setCellValue(student.getPoints().doubleValue());
+        }
+
+        // 将 Excel 文件写入 ByteArrayOutputStream
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        workbook.write(outputStream);
+        workbook.close();
+
+        // 设置 HTTP 头信息
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentDispositionFormData("attachment", "students.xlsx");
+        headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
+
+        // 返回文件内容作为响应
+        return ResponseEntity
+                .ok()
+                .headers(headers)
+                .body(outputStream.toByteArray());
+    }
+    /**
+     * 获取Excel模板下载链接
+     * @return 包含下载链接的响应
+     */
+    @GetMapping("/download-template")
+    public ResponseEntity<String> getTemplateDownloadLink() {
+        // 返回百度网盘的模板下载链接
+        String downloadLink = "https://pan.baidu.com/s/1NUukdPo4qUVbM4V9MWTx2g?pwd=1234";
+        return ResponseEntity.ok(downloadLink);
+    }
 }

src/main/java/com/example/attendance/service/StudentService.java

@@ -3,11 +3,13 @@ package com.example.attendance.service;
 import com.example.attendance.entity.Student;
 import org.springframework.web.multipart.MultipartFile;
 
+import java.io.OutputStream;
 import java.math.BigDecimal;
 import java.util.List;
 
 public interface StudentService {
     void importStudents(MultipartFile file) throws Exception ;
+    void exportStudents(OutputStream outputStream) throws Exception;
     void adjustPoints(String studentNumber, BigDecimal pointsDelta);
     List<Student> getStudentRanking(int page, int size);
     Student findById(Long id);

src/main/java/com/example/attendance/service/impl/StudentServiceImpl.java

@@ -3,15 +3,14 @@ package com.example.attendance.service.impl;
 import com.example.attendance.entity.Student;
 import com.example.attendance.mapper.StudentMapper;
 import com.example.attendance.service.StudentService;
-import org.apache.poi.ss.usermodel.Row;
-import org.apache.poi.ss.usermodel.Sheet;
-import org.apache.poi.ss.usermodel.Workbook;
+import org.apache.poi.ss.usermodel.*;
 import org.apache.poi.xssf.usermodel.XSSFWorkbook;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 import org.springframework.web.multipart.MultipartFile;
 
 import java.io.InputStream;
+import java.io.OutputStream;
 import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.List;
@@ -33,6 +32,9 @@ public class StudentServiceImpl implements StudentService {
             // 读取第一个工作表
             Sheet sheet = workbook.getSheetAt(0);
 
+            // 检查文件中是否包含积分列
+            boolean hasPointsColumn = sheet.getRow(0).getLastCellNum() > 2;
+
             // 遍历每一行，从第二行开始（假设第一行是标题）
             for (int i = 1; i <= sheet.getLastRowNum(); i++) {
                 Row row = sheet.getRow(i);
@@ -41,7 +43,15 @@ public class StudentServiceImpl implements StudentService {
                 // 读取学生数据
                 String studentNumber = row.getCell(0).getStringCellValue();
                 String name = row.getCell(1).getStringCellValue();
-                BigDecimal points = new BigDecimal(row.getCell(2).getNumericCellValue());
+
+                // 如果有积分列，读取积分，如果没有积分列或者积分为空，则默认积分为 0
+                BigDecimal points = BigDecimal.ZERO;
+                if (hasPointsColumn && row.getCell(2) != null) {
+                    Cell pointsCell = row.getCell(2);
+                    if (pointsCell.getCellType() == CellType.NUMERIC) {
+                        points = new BigDecimal(pointsCell.getNumericCellValue());
+                    }
+                }
 
                 Student student = new Student();
                 student.setStudentNumber(studentNumber);
@@ -56,6 +66,33 @@ public class StudentServiceImpl implements StudentService {
         studentMapper.saveStudents(students);
     }
 
+    @Override
+    public void exportStudents(OutputStream outputStream) throws Exception {
+        List<Student> students = studentMapper.findAll();
+
+        try (Workbook workbook = new XSSFWorkbook()) {
+            Sheet sheet = workbook.createSheet("Students");
+
+            // 创建标题行
+            Row headerRow = sheet.createRow(0);
+            headerRow.createCell(0).setCellValue("学号");
+            headerRow.createCell(1).setCellValue("姓名");
+            headerRow.createCell(2).setCellValue("积分");
+
+            // 填充数据
+            int rowNum = 1;
+            for (Student student : students) {
+                Row row = sheet.createRow(rowNum++);
+                row.createCell(0).setCellValue(student.getStudentNumber());
+                row.createCell(1).setCellValue(student.getName());
+                row.createCell(2).setCellValue(student.getPoints().doubleValue());
+            }
+
+            // 将数据写入输出流
+            workbook.write(outputStream);
+        }
+    }
+
     /**
      * 调整指定学生的积分
      * @param studentNumber 学生编号